2004 Toyota 4Runner P0306 Misfire Diagnosis
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- Опубликовано: 8 сен 2024
- What would you do with a car that kept misfiring when cold-started on days under 35degrees F but then runs fine after a couple minutes? Well, 98% of people would of course change plugs, wires, O2 sensors..... But even the 2% of people who know how to diagnose effectively would have a pretty harsh surprise on this one when their main suspicion of the most likely issue turns out negative!! This video shows once again- NEVER diagnose off of just symptoms!!
See Part 2 Here: • 04 Toyota P0306 Pt2-Ca...
Get Schrodinger's Box Merch at teespring.com/...
The other video referenced for the homemade tester is here: • Homemade Cooling Syste...
I have the exact problem. This is the only video I’ve found that goes in-depth about misfire. There’s hundreds of videos about misfires and all they show is plugs and coils. Everyone knows to check that. I’ve spent around $2000 already trying to fix my truck. I can’t thank you enough. I’m confident this is my problem. My truck is doing exactly the same thing as this one.
you have to diagnose on data, not symptoms. just because your truck is doing the same thing doesn’t mean the fix in the video applies. start with a clean slate, collect data and analyze it to diagnose the issue.
@@SchrodingersBox I’ve got the same engine in the video
@@SchrodingersBox I’ve got the same engine in the video. Every morning on first start it has a bad misfire on number five. It throws the Check engine light blinking. Sometimes you can just shut engine off and restart and misfire is gone. Other times you will have to clear codes with a scan tool. But never the less once code is cleared the engine runs like a new one. The engine doesn’t have time to heat up or anything. Just start it, shut it off, clear codes, and alls good. I’ve done all of the basics plug, coil, injector, cam sensor, cleaned MAF sensor. Why would clearing the code do anything. If you have a bad part. It’s bad including head casket correct? Unless it’s an electronic part. I’m no mechanic by no means but I just can’t understand why clearing a code could make a bad part a good part.
The forth pin on a ignition coil is usually a feed back signal and is used by the ecu to monitor the performance activity of the coil when firing typically pins are as follows
1 Positive supply - switched battery voltage.
2 Trigger - typically a 5 V active-high pulse from the ECM to the coil.
3 Feedback - typically a 5 V active-low pulse from the coil to the ECM.
4Ground/Earth - battery negative.
Thanks John. Others have said similar however my electrical Guru agreed with me that it's a PNP design. I actually think yours is probably correct though because I would expect the PNP circuitry to still be internal in the coil. Either way, I'll pull a diagram and find out for sure- I bet you're right.
Yes yes...4 pins on the coil will be found generally on Toyota's.
One pin will be a constant 12volt with ignition switch 'on'.
One a constant ground.
One an IGT signal (pulsed signal from ECU to trigger each spark event....in the form of a positive or neg voltage, dependant on PNP or NPN type transistor used)
Lastly, an IGF signal (gives feedback to the ECU to confirm the coil fired when requested)
Look for the legendary SD (Scanner Danner) Toyota Ignition Coil Testing...His Vids are right here on RUclips.🤣👍
You're correct, ignition+ with a ground, IGT ignition trigger and IGF ignition feedback.
Being quite familiar with Toyotas I can tell that a careful reading of the plugs will show the smallest coolant leak in a cylinder if you know what you’re looking for. Head gasket issues are an age old issue with the 3.4 and the 3.0 that preceded it.
Great video, I work at a used car lot. We get a lot of trade ins most of the time they have some sort of what seems like a major engine repair "rebuild or replace" needed. More often than not it's some sort of cylinder killing issue. Stuck lifter, bend pushrod or broken valve springs. Point being we dive deep and perform a complete diagnosis.
Knowing exactly what failed and being able to prove it is the only acceptable diagnosis our service guy accepts.
Thanks Jose! Yes you are correct. Prior to focusing on diagnostics, I used to "flip" cars- buying cars with "fatal" engine or transmission problems and fixing them and reselling. About 20% of the time the fatal issue was a misdiagnosis (kind of like this video showed) and I'd make a killing on the car because it only needed a manifold gasket or it had a minor electrical problem instead of a head gasket. One car I remember was diagnosed with a rod knock- turned out the cover to the torque converter was bent inwards and the torque converter bolts rubbed against it lol.
@@SchrodingersBox I bought a Jeep with a 'rod knock' to discover the flex plate had cracked all around the bolts. A simple flex plate replacement brought me some nice cash. That it still ran and drove amazed me.
I work on a lot of these engines, but I don't remember coolant running through the intake plenum. I could be wrong though. It has been a while since I have had the lower intake off, so I can have a couple engines mixed up, but I thought that it had a pipe running under the intake from the front to the back of the engine, down in the valley between the cylinder heads.
Also, I have seen a lot of these head gaskets fail, and I love scopes more than the next guy, but I have never seen the head gasket on THIS engine leak so badly that it caused low compression, especially a bad relative compression test. When I check the head gasket, id rather put 100 psi in the cylinder, and watch for coolant leaking into the radiator. Your smoke machine probably only puts out 2-3 psi? I'm not sure that was enough pressure to cause the leak to present itself. I'm not saying that it has a bad head gasket. That's just how I would check it myself.
I have been starting to get into pulse testing, or pressure differential testing, using a piezo element on the radiator to watch for pressure spikes while cranking the engine, and I have had good luck that way as well, since you already had the scope out to do the RC test.
As far as the ignition coil. It has a 12v power supply, constant, and a ground. The ecm sends 5v to a transistor to turn the coil on. The ECM also sends 5V from the ECM that the coil pulls down to ground when the coil fires to confirm that it did fire to the ECM.
But good video! I am going to dig into service info a little more to verify which toyota engine has the coolant in the intake, and which one doesn't.
Your correct on no coolant runing through the intake. Theres a pipe under it. Have seen several head gaskets fail on #6 with no compression loss. Found it with a borescope when letting it sitt overnight.
@@miguellozano8936 are you saying you think that water was coming from the gasket?
Miguel Lozano i know. Lol. But i was trying to not come off as a troll.
Yep- after further review, it's clear the lower intake is indeed dry. Nice call, Voltage Drop. I'll make a follow up video!
Schrodingers Box ... so much for being a 2 %
Great channel. I love the scientific approach. Right now I'm a10%er, striving for 2%!
I used to watch Matt a few years ago.... kinda went away for a while.. now I am back for the excellent sarcasm!
I continue the work today with the miss on number 3 cylinder on the Toyota and found a fuel injector leaking very little . I did the test with a fuel injector cleaner putting pressure on the fuel real and all 6 injectors and blocking the return and found a very small leak removed The spark plug and found gas on the cylinder #3 . The miss got fixed after letting the truck with out running for 10 minutes , I did this 3times to make sure it was fixed. Thank you again for all your teaching Matt
Sorry forgot to let you know the number fuel injector got replace
Number3 fuel injector
As a avid Toyota fan I can say it definitely is a coolant leak in cylinder 6. Coolant will leak down after the engine is shutdown. Causing misfire upon startup. I own a 2005 with the 1gr-fe with 250,000 miles and have had the same erratic code for 12 years. Besides a bit of coolant over time, no other issues. The head gasket part number did change after 2006. So maybe Toyota figured it out. Regardless, I’ve had nothing but great experiences with Toyota.
Another good video, and solid diagnostic approach. Been a long time fan of your channel. Quick tip I've seen on engines with coolant that gets into the cylinder. Pull the plug and use a video scope, or just look down through the plug hole. If it's a lot cleaner than the other cylinders, that's an indication it's likely burning coolant. Basically, as it burns it off, it's steam cleaning the cylinder, and it'll be noticeably cleaner.
Yep a good technique but on this leak I don't think you are going to see the coolant run right into the cylinder. It's far more likely it's in the #6 runner by the coolant passage on the lower intake gasket and it's getting drawn in with the intake stroke. I have a video of this with borescope on my other channel in fact on a car with same exact condition.
Reminds me of a 98 Ford F150 that I got rid of. It had the same symptoms of misfires, very little coolant loss without any visible leaks. One of the sparkplug tubes had coolant in it. After removing the intake, I found that the intake gasket had 2 cracks between the coolant port and that one cylinder with the coolant in it. Great investigative work!
Thanks man. Yes truth be told this is not the first time I have seen this exact same thing as you described. Thats why I came up with the idea after I realized it wasn't a vacuum leak.
Happy Thanksgiving Matt! Great to see you back!
Thanks man, Happy Thanksgiving!
They're the jobs that separate the men from the boys. Good shit bro!
So what’s the procedure to fix this problem? change the head gasket?
There is a handy smoke machine accessory that goes in the intake tube with an inflatable bladder with a tube that passes through so you can hook the smoke machine to. Nice video, Matt.
Nice job explaining everything. Happy Thanksgiving!
Matt, thanks for another excellent video! Love the SBQM channel too. BTW, you could also hold a piece of white paper over the cylinder while cranking...this will allow you to see the coolant (or fuel, or oil) on the paper for further verification.
Yep great idea. I did that in fact- and orange coolant showed on the paper. But when I edited the video the camera showed it as being much clearer that it looked in real life so I didn't include the shot. Too many people would have claimed it was fuel.
Informative and funny, this wrap should keep the air filter fresher hahahaha
I guess after watching this video I'm still confused as to what the solution would be to fix the problem. I am having the same issue. So is it a head gasket problem or not?
Right! me too, I want to know how to fix it
"I hope I get an iron for Christmas."
LMAO
Another great video, It has given me motivation to get back on my project vehicle, a 1988 Ford F 250 diesel. It has an issue with glow plugs not firing from the relay I think. Work has gotten me so bogged down its been on my "back burner". You make me want to re-focus and get it done! When my wife yells at me for being under the hood of that truck on Thanksgiving day, I'm going to tell her its your fault! LOL! Happy Thanksgiving to you and your family.
Glad to be motivating!! I didn't know they had diesel's on the 88. Years ago I built the engine for an 88 F250 windsor for my personal use to make junkyard runs. I called it "frankentruck" every part- even one of the pistons was from different donor vehicles (and they say you can't mix pistons between engines--- well, usually you can't but I found a perfect match). The truck was amazing and really handy when I pulled engines and transmissions! I ultimately sold it to a snow plow company. Man I loved that truck!!
@@SchrodingersBox Yes, Navistar made diesel engines for Ford trucks even back then. Back then they offered the 6.9 and 7.3 engines, mine is the 7.3. I believe they started offering them in 1981. I call mine the "dead man's" truck. It was sold to me from a woman whose father had passed and owned a ranch in California. The great thing about it being in the desert region of California is it is about 98% rust free! After his death, she got the truck and shipped it to Reston, Virginia and she and her husband rarely used it. It was parked for the last 3 years because they couldn't figure out the glow plug issue and they didn't want to spend money for a mechanic as they rarely used it. I plan on doing the same thing you did with yours, junkyard runs, dump runs, a backup vehicle, and for some home improvement projects next spring and summer. I love this truck too!
Nice product placement Matt. :) Before I forget, have a great Thanksgiving! I've enjoyed your content over the years because your good at explaining the thought process of your approach. I think that's as important as the actual fix itself.
Thanks man. Yeah you have been here almost from the start. Always appreciate the feedback and happy thanksgiving
It feels like this diagnosis needs to go a little further to clarify how coolant is making its way into the cylinder, even though I do understand why the customer may want to cut her losses. She may get another year if she decides to ride the horse til it dies, but that decision assumes there is no quick intake manifold fix. Any test will have false negatives, and false negative dye tests for combustion products in the cooling system are pretty common. If coolant is truly leaking into the intake manifold, isn't there a chance of fixing it by chasing down where you heard it leaking? Are you thinking that, after all, it actually is an early head gasket failure, leaking coolant but not losing compression yet?
Yes I believe what I’ll do is try a borescope or dye test to show but it is absolutely possible for coolant to get into a cylinder through the intake gasket. If a coolant runner to the lower intake is adjacent to an intake runner, the coolant can enter the intake runner. I could also get a correct coolant pressure adapter and show decay in the coolant pressure over time and if did it long enough I could probably build up a pool of coolant in the cylinder.
But I have no question it’s not the head gasket because compression at 160PSI would absolutely have shown variation. I can hear the coolant leak gurgle past the intake gasket at only 20psi. At 160 PSI - that cylinder would have lower compression for sure if there was a head gasket leak.
I agree that it should go further, because this engine does not have coolant runners or passages in the intake manifold like he is assuming. That being said there is only a couple of ways coolant could make it into that cylinder.
@@craigdavis5965 It definitely has coolant passages on the lower intake, not the upper.
I was just about to propose buying a bore scope, if you did'nt have one, when i saw your comment, about it. Using it from the moment you confirmed the coolant leak, would've conclude the final diagnosis, and save time.
@@SchrodingersBox Matt, that's a good point about the difference in pressure to cause leakage. The only way I can imagine that happening inside the cylinder would be if there was some kind of flap valve effect, allowing coolant to flow one way but prohibiting significant combustion gas decompression in the opposite direction.
Nice work as usual. My guess is the garage she took it to might have seen that the spark plug on number 6 was clean and guessed head gasket failure from the coolant jacket but a chemical test or a relative/compression test would have ruled that out in 10 minutes.
You know my Toyota turd wagon has those 4 pin coils but only has 3 wires in use on them. I always wondered what the 4th pin was for on them as 3 wires gives you 12V, ground and the trigger signal from the engine ECU.
I agree- coolant on spark plug=blown head gasket to the parts changers!!
I am working on one exactly the Same with a miss on number 3 cylinder , I can not find The problem , I did not know the coolant runs. Through intake manifold When said You intake manifold you mean the lower intake manifold. I will check the coolant system tomorrow thank you
Very helpful! How did you attach a compressor hose to the radiator?
One thing I'm not sure about (and this is a dumb question) but is this be a head gasket or an intake gasket problem?
This is a lower intake manifold gasket problem. The link in the video descriptions answers your other question.
@@SchrodingersBox i was wondering the same thing. thx for your vids & knowledge
Happy Thanksgiving, Matt! Another great video.
Had a misfire on my 2004 4Runner during first 30 seconds of a cold start and was not losing coolant. Engine light, VSN, and one more light I can't remember now was on. Sometimes a flashing engine light. Pulled and inspected the spark plugs to find oil covering one plug. Replaced those gaskets involved and no misfire.
Head Gasket?
I’m misfiring on cylinder 6.
@@matthewhooks452 Check for oil on your plugs and if the electrode is still there.
What does oil on the spark plug mean?
So was it a head gasket after all?? I missed the final conclusion! Thanks mine is doing the same thing when cold.
Matt, thanks for the video.Always waiting on you men.You be like best.
So what is causing coolant to leak into the cylinder if its not the head gasket, how would you fix this problem?
Matt, Thanks for the video. I have one of these that uses a very small amount of coolant. Mine still runs good, never had the “miss when cold” issue. There is a widespread belief on the forums that there is some factory defect on head gaskets from 04 and 05. Makes me wonder if many of the HG failure diagnosis are intake gasket leaks instead. Interesting that they almost always say it’s cyl #6.
EXACTLY!!! Thanks for the comment. Yep- it's exactly that "parroting" which causes this widespread misbelief. I checked TSB's and there is no TSB for this condition (like there is for the 3400 and 3600 GM's that I mentioned in the video).
Also it's why so many people swear by head gasket quick-fix fluids. It's because they are fixing an intake leak at only- what- 20PSI vs a head gasket leak at 180PSI!!!
Love your thinking- always be critical!!!
This is very true I was gonna make the same comment...I am also one of those 04 vehicle owners which is sitting in my driveway for the last 8 mths cause of this issue. I just purchased a new motor to do a engine swap this week. I can’t believe this video was just made at this point in time...and I have never heard of this be a possible thing EVER!! Ive only heard and know one thing coolant in a cylinder means blowin head gasket....a blowin intake gasket? WTF? NEVER ONCE HAVE I HEARD THIS WAS EVEN POSSIBLE OR ACTUAL THING!!!
I am beside myself right now...thank you for the video and knowledge. But now I will sit and stare at the ceiling confused and try to make sense of how this is possible.
It would be interesting to see the original plugs. Maybe the number six plug looked cleaner than the others.
Yeah even the new plug I pulled out had a slight discoloration but you couldn’t tell if it was fuel or coolant or just discoloration from misfire causing deposits.
But Matt, I'm confused. Isn't one reason for coolant in the cylinder a blown head gasket?? How else is it getting in there?
it is getting in there from a coolant passage running from the head to the lower intake manifold that is leaking. The passage must be adjacent to the intake runner for #6. It’s definitely not from a head gasket- it’s from intake gasket.
@James Carroll Exactly, James. The lower intake has coolant passages- that run adjacent to some of the intake runners in fact. The upper intake is dry.
So the other shop would have fixed it by mistake replacing the intake gasket when going for the head gasket. It was not a bad guess from the other shop but it's maybe a $350 extra fee for the customer.
I gotta tell you this is the first time I've seen this fault and I also would've guessed something was wrong with the head gasket, so thanks for sharing. Keep up the good work!
Another Great vídeo Matt I like seeing again, a bit hug. 👏🔧👌
Happy Thanksgiving from Down Under...
That’s what she said!!
4 pins, 12V, ground, Ig-trigger from ECM and ig-f feedback to the ECM.
Please explain what the IGF Feedback and Ig trigger is exactly.
Schrodingers Box trigger is command.
Ig f is each coil, parallel, confirming the work is done back to the pcm. Essentially allowing all coils to be checked electronically via one wire
@@SuperMarioDiagnostics Ah so basically you are saying it is NPN design and there is not ground side switching of the signal but rather the signal is a positive feed input like on a three wire design?
Schrodingers Box it's a 5 volt command to a smart coil
@@SchrodingersBox You are correct Matt that this is a NPN design where the command signal for each coil should be about 0-4VDC. The command signal which drives the base of the transistor inside the coil will go high to turn on the coil and goes low to turn the coil off. On the feedback signal, there is one line from the PCM which feeds all the coil's internal electronics and should be about 5VDC. When one of the coils fires, this 5VDC line will pull low letting the PCM know that the coil fired. Great video by the way and hoping you and your family have a great Thanksgiving!
Nice ! Matt, hope you and the Mrs. Have a Happy Thanksgiving ! Take Care !
Thanks Billy- to you as well and thanks for your many years of support!
I'd like to see a camera in the cylinder to see where the coolant is coming from.
Yeah agreed. Actually you probably wouldn’t see it dripping into the cylinder as much as seeing it leaking along the coolant channel gasket and maybe into the intake runner but not “pooling” up around the piston head. I do have a video on my other channel were I catch a mystery coolant leak with a borescope in the intake. It’s a much more minor flow of coolant than you would expect.
I have been working on toyota's and honda's and nissans for over 40 + years and I can tell you that is deffinatly a head gasket. I don't want you to call me an ASS HAT but cast iron blocks with alluminum heads is a common problem, those chemical testers are not reliable. Even american cars that went that route in the 80's and 90's had the same problem, they leak coolant over night it blows out in the morning and your good to go, do it enough then car runs low on coolant and it over heats, look at that, the car had a head gasket problem first before it over heated, amagine that! As for your coil one is power, one is ground, one is an IGT wire witch is a 5 volt square wave to the coil to fire it and the last is the IGF wire witch is 5 volt square wave from the coil back to the computer that tells the computer that the coil fired. As for customers that think they know what's going on with there cars, they don't , trust your own instincts.
So after looking into this, it appears you are correct. Others have also validated the same. I'll definitely make a follow up video!!
Happy Thanksgiving Schrodingers!
You too man!!
From the point of view of the garage that "misdiagnosed" Many shops will replace plugs as a matter of course before even looking for the problem. This was more of an old school approach from the breaker point and carburetor days.It sounds like they probably did find water in the cylinder, however they do not really have the potential to make very much money out of an intake manifold gasket job. Whereas a head job involves only a little more time from their point of view and they can make money on the outsourcing of the machine shop work (even if its not actually required they are likely to have a policy of machining every head), they will also be doing the timing belt so they will add the timing belt job to the bill. During the repair they would have found the manifold leak or they would have replaced the seals at any rate to it would never be proved that it was not the head gasket.Anyway by the time a car is 15 years old a general top end rebuild is not actually a bad thing to do for the customer in the long term.In a way how is this different from what most shops do with a sticking brake caliper. They replace the caliper and charge a few hundred when maybe they could have replaced 5 dollar square seal in 15 minutes?All this is why I fix my own cars. I can usually work out exactly what part to replace with techniques I learnt form channels like this.
So,where was the coolant leaking from? blown head gasket then? the first mechanic was right?
If it was leaking at the head gasket it would have failed the chemical test for excessive Co2 in the coolant.It could be a crack in the head -- inspection camera in the intake would be a good next step.
My claim is it was leaking from the lower intake manifold spilling coolant directly into the intake runner.
What did you do to fix the coolant going in to the cylinder ? Tks
I had to replace the head gasket.
Ok thank you sir I’m having same issue on cylinder no 5. Just over 200k miles. Which head gasket u recommend ?tks
yeah I would confirm with a leakdown test and then I would remove the head and magnaflux and measure for warp and resurface til it’s in spec. Once in spec I would use any head gasket you choose- I have used them all and there really is no difference. The lowest cost ones I often use are from a place called “Engine-Tec”. I got almost all my engine rebuild parts from there.
I was wondering when we would get a new video. I'm studying under you. Class is in session. I will rewatch in the a.m. I'm not firing on all cylinders this time of night. Thanks for the instruction.
Hey you’re back lol.
Latest accomplishment was replacing the fuel water separator valve on my hubby's 7.3L diesel F-550. Test fitted the T15 tip in the new screws, come to find out the part on the truck was T20. Got it though. No more rainbows on wet pavement from fuel drips. Learn as we go...
@@farmergirlofchickens8779 Nice work. You have a video of that?
Maybe I need to start recording my Automotive Adventures. As a matter of fact, I think that will be my channel name. Thank you. 💡
I’ve got the same engine in the video. Every morning on first start it has a bad misfire on number five. It throws the Check engine light blinking. Sometimes you can just shut engine off and restart and misfire is gone. Other times you will have to clear codes with a scan tool. But never the less once code is cleared the engine runs like a new one. The engine doesn’t have time to heat up or anything. Just start it, shut it off, clear codes, and alls good. I’ve done all of the basics plug, coil, injector, cam sensor, cleaned MAF sensor. Why would clearing the code do anything. If you have a bad part. It’s bad including head casket correct? Unless it’s an electronic part. I’m no mechanic by no means but I just can’t understand why clearing a code could make a bad part a good part
Start with a basic fuel trim analysis as the first step.
@@SchrodingersBox I did the solution test with the tube and solution. It came back immediately positive for blown head gasket. Is this a reliable test?
Very reliable.
Happy Thanksgiving, Matt and Vicki!! 🇺🇸🙏
You too my friend!
Happy Thanksgiving
The coil terminals should be 1-constant + 2-constant- 3-trigger 4-diagnostic/data signal
Few years ago i fixed a misfire in my brother's car that was caused by a coolant leak on a spark wire from a cracked coolant passage in the intake manifold, my first thought was that the water drops from the windshield.
The car was 1997 mercury grand marquise.
Ive had to replace several knock sensor wire harness on these engines due to rodents. They sit under the lower intake. There is no coolant passage there. There is a coolant pipe that runs from the back of both cylinder heads to the front thermostat housing. Also have had this issue of coolant entering #6 cylinder. Let it sitt for a few hours after warm up and could see the coolant leaking into the cylinder between the head and block with a borescope. I could see the droplets.worth giving it a try. I own a tacoma with the same engine and hope mine does not fail.
Yep- after more review, you are correct- it's a dry lower intake. Follow up video coming.
Just had this problem multi cylinder misfires as well as individual cylinders lower and uppers replaced cleaned it all up put it back #6 still swapped coils injectors nothing I'm lost
Oh yeah there is smoke coming from the intake exhaust I'm assuming or combustion fumes replaced pcv valve it was plugged entirely still rattled tho 150,000 1gr-fe
great to see you back, Bernie
as to the "elephant in your pantz" ...
check with yer boyfriends
I did. Thats why its called the elephant!
@@SchrodingersBox TMI !!!!!!!!!!! :)
@@embreesmith7613 well ya deserved that 1 Embree! HAHA!
@@TheDisgruntledMechanic You deserve the "elephant" , Mike !!
@@embreesmith7613 haha! humm maybe I do at that!
My 2002 4Runner has number 3 misfire. I pulled the coil and plug. The plug was soaked in gas. Bad coil? The problem is intermittent.
Could be. Could also be it’s covered in gas from no compression or leaking injector.
I believe I have an injector issue w/my ‘06 4 ltr 4 runner, 200K miles. I KNOW asking for a diagnosis this way sounds ridiculous but here goes.
6 new spark plugs & new coil packs on cylinders 2&4. BTW I’m retired so I drive it 1-4 times weekly.
#4 cylinder has “thrown” a code turning on the dreaded Chk Engine light. Please read on
A. When starting cold from sitting over night, consistently misfires. I shut it off. If I immediately attempt to restart, it may run on 5 or 6 cylinders. 5 cylinders? Shut off and restart - usually 6 cylinders. Once running/driving allowed to warm up, I can run errands all day and it’s fine even after sitting 2 hours.
B. Recently I’ve tried and succeeded w/turning key to ON, waiting ~about 20-30 seconds. Then turn key to Start and it CONSISTENTLY runs on 6 cylinders first try. So much so, the Chk engine light turned off and has stayed off now for the last 15-20 times I’ve used it.
neighbor-mechanic says no tell-tale smell of running rich or coolant.
Post from 4Runner.com says injector - verify by remove* spark* plug* after sitting over night. I’m a bit short on tools** for this* task. And likely same for injector.
**torque wrench
Maybe? To anyone thanks in advance and for reading this far
I forgot. If it starts on 5 cylinders and I don’t shut it down and restart it continue to run on 5.
Once I was in a hurry. I drove it down my street. When I stopped at the corner, it was still running on 5. Shut down and restart cleared it. Confused? Me too
Nicely done.
I’m not familiar with this engine, But how does the coolant find its way to intake manifold?
Nearly all engines have lower intake manifold ls with coolant runners that allow coolant from cylinder head to enter the lower intake. If that lower intake gasket leaks coolant and the coolant passage is near an intake runner for a cylinder, the coolant can be drawn in past the intake valve and into the cylinder.
@Eric Wood You know, thats a good point Eric. That's possible. The woman seemed to be pretty adamant they said head gasket and also she didn't have a recollection when I mentioned "intake gasket" or anything.
But that's a really good thought. Even so, however- at best they still threw plugs in a car with an intake manifold leak lol.
Anyway,
I think the original mechanic was way ahead of you. He found the coolant leaking into the cylinder and its not a far reach to suspect the head gasket, a minor failure that doesn't effect oil galleries or compression.
could also be a cracked head, and that's where ide put my money.
Can you explain how the coolant would be leaking from the intake manifold gasket into the #6 cylinder when there are no coolant passages from the cylinder head into the intake manifold at all. Just curious.
The lower intake has coolant passages.
This would tell her not to trust that professional mechanic
Seconding the part where you said the early 2000s Chevy cars had this problem. My 3.5 Malibu did exactly what happened here.
Yep- very common problem. Most of them leaked right into the oil valley instead of the intake runner and thinned the oil. Most owners realized the issue when they developed a rod knock.
Thank you sir to shares your experience
Great to see another video from SB! I am not familiar with the design of the Toyota engine. The compression test was good so the leak must be really tiny. Wouldn't the coolant leak be coming through a portion of the head gasket?
Thanks Sandbag. Even a small head gasket leak will show on a compression test or leakdown. Remember we're talking 160 PSI- and way more running. It would show.
The cause of the leak is because the LOWER intake manifold also has coolant passages. If the gasket fails at a coolant passage it can leak coolant into an intake runner and into the cylinder (or more likely get drawn into the cylinder).
@@SchrodingersBox So I just finished up a 2005 4Runner head gasket replacement due to coolant getting into cylinder 4 and 6 less than 2 weeks ago. This caused misfires in cylinder 4 and 6. The engine was a 1gr-fe, and the one you are diagnosing appears to be a 1gr-fe also. Camera confirms, and opening it up confirms it. I actually took it down to a trusted shop who did a compression test, and they did not detect any compression lost. They did do a coolant test and finally confirmed what I found. I did let them know of my findings ahead of time. The spark plug was tan/brown in color from coolant. Cylinder 2 spark plug looked perfectly normal and was used to compare with 4 and 6. I don't believe or remember the lower intake that bolts on to the cylinder has coolant passage. The cylinder head did have coolant passage. I also remember because I had 1 extra bolt that I could not find where it would go, until I moved wire harnesses all way out of the way. Once I found the last bolt hole, the l finally had the lower intake torqued down. Then the plastic intake was bolted down. Reviewing my pictures I took, i am confident in my very very amateurish assessment that the lower intake(aluminum) did not have coolant passage. I would describe it as a mating part only. The 2004 and 2005 4Runner are known for blown head gasket, and I am leaning towards blown head gasket for yours. Head gasket was replaced by me and a friend, and no more misfires after. Then again, I have been wrong toooooooo many times in life.
@@phimane Well Phi- remember if cylinder head was replaced, intake manifold gasket was also replaced and maybe if just needed that. Also, in the video you heard the coolant gurgle with the intake manifold was pressurized. How can that possibly happen if it's a head gasket problem but not show compression loss in a cylinder?
@@SchrodingersBox I would definitely say that the issues I had may not be the same to yours. It could appear to, but may not. I always say, the guy who is closest to the actual thing you are troubleshooting, go with that person's gut and experience instead. I simply offer my findings just in case it could potentially apply to your case.
I do want to thank you for opening my eyes and mind in troubleshooting using critical thinking. I am not an auto mechanic, but with your videos, it made me better and more confident in the issues I run into for my personal vehicles. For the vehicle I worked on, I did confirm a blown head gasket via multiple evidence, and then set the course of action.
Keep making awesome videos that will help us all!
@@phimane Ok--- let me repeat what you just said and see if you still agree with it. You said "The person who is closest to the actual thing being troubleshooted, you should go with THEIR gut instinct and experience". As opposed to going with data and scientific analysis that would necessitate a single correct conclusion.
Are you sure about that? I have hundreds of videos where the person closest to the troubleshooting threw in plugs, wires, O2 sensors, MAF sensors, MAP sensors, A/F sensors, fuel additives, etc on their gut instinct and experience before the car comes to me.
You sure you want to go with that philosophy?
Sorry i don't speak english very well, so you speack so quick in your video😭😭😭.
Thank you for this knowledge.🙏🙏🙏
I want to know by witch way coolant can go inside the cylinder 6? You did the compression test it was ok. Or it going by leak intake manifold ?
only time you should change something just because is oil seals, oil and oil filter and thats only if you've checked the oil and filter to make sure there's no chunks and only if you've got half the engine or gearbox apart already and it doesn't make sense not to change the oil seal
New guy "on the block" lol
I'd still check for fuel pressure drop just to eliminate the possibility... but I'm still curious on the repair.
And Happy Thanksgiving and Happy Holidays in general!
Hahaha "on the block"!!! Nice one. Yes I agree- leaking injector a possibility however very unlikely. But it was next on my list if I didn't find a coolant leak. The reason a FI is less likely is because there is no reason to expect it to only leak when cold. It would be expected to always leak past the pintle and thus I'd see rich fuel trims which I did not see (fuel trims where positive 6 total on B2 and positive 2 on B1).
Plus, on a leaking injector directly into the cylinder, you would definitely smell the fuel- the fuel system is at 60PSI so thats a lot of fuel that would zero-out right into a cylinder.
But I agree- a variable I didn't really eliminate.
Its always a good day when Schrodinger's Box posts another video!
Also note the coolant reservoir is below threshold. Telltale sign!
Good video. Was the noise eminating from the spark plug hole or the intake manifold?
So what would be the fix if you said it did not need a new head gasket?
Intake gasket.
So what did we determine it is lower intake manifold?
Good job! Great video!!
Thanks Robert and Happy Thanksgiving!!
What was the fix?! What did you need to replace?
nothing to fix! that’s the best part of knowing how to diagnose it.
I have the same issue miss fire only cold start on my 4runner. What did you do fix it? Please let me know thanks
All I could figure is the pressure in the upper intake I pulled a vacuum line while the manifold was completely out of the vehicle and it released vacume is that normal?
So was the head gasket the issue with this truck? I’m having the same problem with my 05’ Tacoma
I would use a bore scope in the cylinder and remove upper intake manifold before determining coolant is getting in to the cylinder from intake gasket this engine is know for misfiring from coolant
Yep I agree- I'll do that when I repair the car
I have same problem in my Toyota 4 runner 2006 how to fix that please reply
what data do you have?
Does the intake manifold on this Toyota has a coolant passage,
The lower one does at each corner. The upper one does not have any
Schrodingers Box so what do you think about cylinder. 3 it is one of the center cylinder is there a change to have a coolant leak
Thank you again for answering back
so was it a blown head gasket or cracked head?
So what is the fix?? I have an ‘04 just like that with the exact same issue. Thanks
head gasket replacement.
What happens on these is when the engine is at operating temperature and shut off for hours, coolant will pool onto the top of the piston from a breach in the head gasket. It's common on these Toyota 4.0l engines and it's always #6 cylinder that misfires.
If that's so- why is there no compression loss?
Also- I checked the TSB database- not a single mention of this in any TSB?? Seems to me there would be a TSB especially from a 2004.
Schrodingers Box it won’t be noticeable enough to show up on a compression test. It may show bubbles in the radiator if you do a cylinder leak down test. That would be another method, but pressuring the coolant and pulling the spark plug, or pulling the plug warm and let car sit a few hours is the way I do it.
Schrodingers Box this problem has been discussed on Alldata community, IATN.net, Identifix, and Diag.net
The previous mechanic who is quoting head gasket work is thinking....
"yeah but how do I know you didn't switch cars when you did the compression test. All I saw was the gauge!! You are tricking me!!! You sir cannot be trusted!!"
Yep that is what he is thinking alright.
Good point lol however if he had that much reasoning ability he would have done the method I used and diagnosed it correctly the first time and I’d never have seen the car in the first place. hah ha!
Is the diagnosis conclusive? How the coolant gets into the cylinder, where is that proved?
In 3 parts- pressurizing the intake, pressurizing the cooling system, and showing the coolant ejected from cylinder.
Thanks Matt. Happy Thanksgiving.
You too Don!
I put transmission in a year ago and now it's down shifting in 2nd gear and when it shifts on out it's right back down shifting again it just started this all of a sudden is there anything you can tell me to do? D.J.
is it going into limp mode?
Damn I read comments 1st! I love all asshat parts cannon firing parts pirates! 98%'ers unite! now back to video! And I will send you one of my pullover hoodies. You wont have to worry about getting that one dirty!
Oh I would love that!! I'll do same for you!
BTW- you know I always try to present a "mystery" format in my videos- why would you spoil the ending by going to comments lol!!!!
@@SchrodingersBox email me a mailing address and I will get 1 in the mail. Large?
@@SchrodingersBox as for the mystery-- the suspense was just killing me!
@@TheDisgruntledMechanic Will do!! It would be Extra Large. You?
@@SchrodingersBox 2xl I like the extra room!
Yes another video!
Lol, yes I felt your pain!! happy Thanksgiving!!
Any chance of a conclusive follow up please Matt?
We heard the gurgle gurgling...and we know the coolant was getting into the cylinder from somewhere...but still a little unlclear where the gurgle was gurgling from?
Agreed. Will do!
Couldn’t have you measured engine vacuum with a vacuum gauge at startup as a baseline measurement?
No- because you can't determine effectively if low vacuum is the result or cause.
I really want to try out. I missed the last time because my crap car broke. Can I still try again?
So what's the fix for that? A new gasket set or a new intake manifold to go with the new gasket set?
See part 2
Did use use volts measuring for the relative compression test ? I thought you would have used an ampere measurement.
You can use either, however ultimately you are actually only measuring volts. The amp probe converts the magnetic field to a voltage (less than 2 volts). When you use amperage scale, it automatically does the math and converts that voltage to what the amps were- but I just chose to measure the volts because I am not interested in the quantitation in this application, I am only interested in the relative consistency, especially since I already have a baseline of 160PSI on one cylinder.
So the original shop was correct about head gasket issue in the end?
yes but I doubt they really diagnosed it thoroughly.
@@SchrodingersBox Yeah, they prob just read on 4runner forum, which is full of "if your #5 or #6 misfires - its your head gasket" doom sayers.
My 1995 T100 has three coils on one bank that controls both sides
I’m having this problem change coil, sparkplug, fuel injection, for cylinder six still having a misfire
Not following - you changed coil AND fuel injector? there was no spark AND no fuel at one cylinder??
@@SchrodingersBox still getting misfire after changing coils and fuel injection and spark plugs
Ok so you had no spark AND no fuel?
@@SchrodingersBox I thought that was my problem. I changed those component, but still misfiring.
Ok so again- which are you missing- is it spark or fuel? That’s the first step you have to determine.
When you make the relative compressions test with the scope. Do you measure voltage drop or amp? What are the best method from you Perspektive voltage or amp.
Great question- you can do either. I do amperage because i find it gives better resolution on the scope. I have done voltage drop and in fact the Picoscope has a preset for doing relative compression using voltage drop but the resolution always seems way better with amperage.
I used to only do amperage on the positive feed to the starter motor with the reasoning that it is a more”pure” sample since there won’t be any noise from any other accessories or anything if I were to go on the battery negative. however in recent years I found that more and more, it’s hard to isolate the cable for starter motor so I have been using battery negative much more often and it turns out the signal is the same- probably because amperage from the starter is so high it makes any accessory amperage on the negative insignificant by comparison.
@@SchrodingersBox thank you very much. Do you have some video where you show how do detect missing fuel as reason for random misfire. Some say that you can see it on an scope on secondary ignition pattern.
I absolutely do! I think it’s called misfire diagnosis DIY vs Professional mechanic.
Hi, Someone wants to sell a 2002 4runner, 188K with the following symptoms, was misfiring on pickup only, smooth after cursing speed, no rough idling, run hot a few times due to low coolant, never changed radiator or engine tuneup for 100+K, have to top off coolant every other month, drives fine other than misfiring, smell coolant in passenger cabin? no gump in coolant, engine oil changed, A professional mechanic also said is blown headgasket. Your opinion would be appreciated.
Impossible to tell. What data do you have?
@@SchrodingersBox Just that it misfires, coolants needs to be topped off, runs warm to hot a few times before, idle is fine, smell coolant inside of car, no gunk in coolant reserve tank, never changed spark and wires. that's what I have. 02 4runner with 188k Asking for 6k, accepted 3.5k.
Those are symptoms. Need data like in the video to diagnose and give an assessment.
Good job
where are you at? i need help diagnosing a misfire?
Denver colorado.
Watch your videos couple times as diagnostic tech. I hate to see you possibly miss a common thing I see with this engine. Could you boroscope the cylinder to confirm source of leak. Not sure how the other mechanic narrowed it down, boroscope helps narrows it. Keep up the great videos.
So I actually have a video showing that on my other channel to catch a “mystery coolant leak”. Bore scope on this type of intake though is just about impossible.
@@SchrodingersBox boroscope the engine cylinder and make sure its dripping off the valves and not the headgasket. Just prove me wrong is all I'm asking. Have you fixed it yet?