1991-95 Toyota Pickup 4Runner 3.0 3VZE air flow meter FIX
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- Опубликовано: 18 сен 2024
- I noticed poor performance from the 3VZE motor. This video documents testing the air flow meter, disassembly, and correction of erratic and improper signal output.
The document I found is located here:
htftp.offroadsz...
The entire service manual link is here:
ether3al.com/F...
I just want to say thank you for being very thorough on finding out if the vafm was the culprit. My father dug out two units that he had stashed away and I tested one, took the chance and cleaned the Contacts, plugged it in and the truck roared to life without the choppy idle, on the first click. Of course there was a few minutes of happy tears, all I’ve ever wanted was my dads truck to run again after sitting for years. Thank you from the bottom of my heart. She still stumbled, turns out the egr valve was really really clogged and couldn’t justify a 100 plus bucks to replace it. So I grabbed 20 bucks worth of flat stock from Home Depot and made some block off plates. Now she runs through all gears, and I couldn’t have been happier actually taking the time to mess with a multimeter. I don’t like electronics, but I got over it. Now where to send the broken vafm to be refurbed lol, I like to have back ups
So happy I could help, thank you for sharing!
You are more of a scientist than a mechanic. I am impressed, nice job.
Thank you!
My 1990 4Runner 3VZE had the orig Denso dark green water temp sensor on the plenum at the rear of the engine. It was 34 years old, and had a crush washer on it. I am the second owner, Changing that to a new OEM Denso authentic water temp sensor & sticking with authentic Toyota long life coolant made a difference on mine. I was running rich. VERY careful to buy only Denso authentic parts. That orig sensor was extracted unbroken by me by using a crowfoot 19mm gas line socket by E-cowlboy and a can of CRC Freeze-off & a long straw. The new one & a crush washer exact size as the old one caused no leaks after install. Used no thread sealer.
Very good information! Thanks for this!
I've had engine code light on for over a year. It's the one that relates to engine running rich...26 if I remember correctly. I did change the engine temp sensor years ago, but don't recall if I went with OEM or not. I have so many potential problematic areas that i don't know where to begin. Plan is to do water pump kit, new radiator hose kit, new distributer cap/plugs/wires, and anything else I will touch when doing water pump. The issue is random low power. Sometimes I can drive for week just fine, then suddenly the same hill will see me crawling at 5-10mph. I think part of that is coolant leak somewhere. I'm topping it off once a week with water and ever few months changing the coolant completely. Other issues are ongoing low idle engine shake. It rattled my exhaust loose after a year of driving like that. The code 26 has huge list of potential issues...compression, 02 sensors(which I changed few years ago, injectors(also changed few years ago), and maybe 10 more items. If I were to change all of them I would spend more than a new engine, or cost of swapping in a 3.4L. At this point it could transmission(also swapped that some 5 years ago), or could be my new cylinders... I can't get any mechanics to even touch my OB1 system. One guy says it runs better than most. That's because he drove it when it was running okay. The issues come and go at seemingly random
You can also fine tune the AFM to make the engine run richer or leaner. I have adjusted mine plus the timing and it has got some spunk about her which is pretty impressive for an engine with 436,000 k's. I can honestly say that this motor does not fall into the category of the 3.0 slow. 👍
Nice! Mine doesn’t seem to have a whole lot of power, but I also don’t know much about the history. What did you set your timing to? I’ve got mine at about 12btdc at the moment.
@@shanesgettinghandy I hear 12-14 btdc is most common, some people take it to 17+, I'm about to set my afm 2-4 clicks leaner, lotta write ups and vids about that
@@shanesgettinghandy yes, 12-14 BTDC seems to be the general consensus, although the 3VZ (as well as the 3VZ-FE) has naturally very high anti-detonation characteristics so 17 BTDC is also quite common. Your number one goal however should be correct air fuel ratios. In a perfect world consider installing a Wide Band Air Fuel Ratio sensor in your exhaust system but as a Plan B use a good wide band exhaust analyser. From there, you can fine tune Air Flow Meter in the following areas, (1) the vane door spring resistance, (2) the static arm location and (3) the idle air/fuel mixture setting. With a good Wide Band analysis scanner you'll be able to get close to 14.7: 1 from idle to WOT.
The Denso Fuel Injection system used in the 3VZ engines was licensed from the Bosch L-Jetronic system - it is, for all intents and purposes, a 100% clone of the Bosch system. Here's an article which explains how to super fine tune the L-Jetronic Volume Air Flow Meter, and it applies to your 3VZ engine too.
www.itinerant-air-cooled.com/viewtopic.php?t=7761
Edited to add: The ECU motherboards on these older Toyotas (like most motherboards which are 30+ years old) are occasionally prone to leaking capacitors, and sometimes this causes the ECU to use fallback settings in the Fuel Injection without actually throwing a Check Engine Light. It's not uncommon for this to happen, but the good news is businesses like "ECU Team Corp" have the skills and knowledge to 100% repair any engine ECU, across any brand.
@@ivanjulian2532 Fantastic tips, thanks so much!
this guy is correct. i changed my ecu capacitors out with replacements from digi-key (these can be researched if you google lexus/toyota ecu capacitors) my particular truck ran what i thought was good for 30 yrs old but upon changing caps it runs and sounds like its brand new! shifts different...better, responsive, injectors quieted down. i found a few leaky caps. you could not see the leaks until they were desoldered off the board. 20 dollars for caps and a few hrs. its the best bang for the buck ive ever had with an old vehicle.
Another little trick on this 3.0 engine: the air filter has a couple of small holes on the edge. These must be lined up with some small holes in the air filter container when installed. If the holes are not aligned correctly the engine will not start.
Thanks for this!
My truck didn't start after replacing my air filter, assumed it could be everything else but the air filter, especially the fuel system or maf sensor but everything is completely fine
Dude thank you, I got my forerunner going after doing this!
Excellent!
Nice 93 Toyota! Those are hard to find! I have a 01 Tacoma 4 cyl. 259k and still runs great.
The early Tacomas are super nice too! I had my eye on a 1997 for a bit, but the '91-'94 pickup was my ideal truck and I finally found one that hadn't been severely molested or rusted out.
My 4Runner with the 3.0 is having a limp mode issue where it won’t let me rev past 2000rpm. While everyone told me it’s TPS. I checked that and it’s still in spec. But someone also told me to check the MAF (or AFM)
200-600 ohms is the specs and I did exactly what you did. I did find out that the AFM had 3 spots that read as low as 100 ohms. So my guess (based on what I’ve learned in this video and trying it on my truck) is that my AFM is broken electrically
Did you ever fix this my 4Runner is doing the same thing, also sometimes will surge from 500-1k RPM
Awsome video man. I watch alot, since I'm always working on junk. Lol and this is one of the best.
I love working on junk, and you're right, this is my favorite junk I've owned yet. Thanks for watching!
My 93 3.0 5 speed 4 runner has massive power when cold. I bought it broken 2 years ago and it runs good but I know it can run better. So for the 1ST few minutes when I start it if I give it too much gas it will stall out and be kinda hard to start afterwards. After a few minutes it's fine. But sometimes when I make a right hand turn I get a boost of electrical power and it runs awesome. Has lots of power. So after watching this video my potentiometer has fresh silicone on it were you removed it plus it came with a spare unit in just sitting in the back. It runs pretty good but when on the freeway I get spark knock on the slightest of hills. I just had a new timing belt installed and everything attached to it. And jumped the wire to time it at 10 degrees before top dead center. The spark knock sensor has been moved to the top of the motor and I'm,thinking about a new one from Toyota might be my solution. I tried a new igniter but it made no difference so I put the old one back it. I know it can run better because you can feel it unleash the power every once in a while. Bad coil? I just had a new fuel pump installed. Love this old truck.
Dang, this one sounds tricky! You’ll likely have to eliminate one variable at a time. Spark knock on the freeway might be a timing issue, but it sounds like you checked that. The sensor should just be in case it happens, but not relied on normally for prevention. Good luck!
My '76 Datsun has an AFM just like this. You can test your air/fuel ratio too and adjust mixture with this oft-hated gizmo.
Good to know!
Damn. johnny sins is really a man of many trades
Thanks for this insight. I recently put a snorkel on my 95 runner and it will bog down after shifting into third. I assumed it was an unhappy air/fuel ratio but this has me wondering.
cool pretty clever man !
I Gutted my Converter and EGR. Lots of problems went away. Put adapter on my O2 Sensor. No. Check engine lights and my Yota come Alive
If the reading is that low, that will be a 22re metre, 3vze ones are supposed to be around 400-600.
So it appears I was looking at the 22re section of the manual, and you're right, the 3vze section shows 200-600 ohms, instead of 200-400. Thanks for the info, and now I wonder if this truck has the wrong meter installed. I'll check into it.
Mine threw. 31 code and I think it’s the same problem but I’m thinking I need to replace it there is some corrosion under the cover
Dang, that's too bad. Let us know how it ends up.
I have a 89 4runner 3.0, when i first got it, it ran well but smelled a little rich and had soft throttle response. No trouble codes were set, it stalled one day and wouldn’t start again. I got it started by jumping the fuel pump, using starting fluid and disconnecting the AFM. It would run poorly and die if the AFM was plugged in. Using your video I ohmed the AFM and it was out of spec. I’ve replaced it and that apparently was not the problem. The fuel pump doesn’t run with the key on, but if I jumper the fuel pump, and disconnect the AFM it will crank and run poorly. Once it’s running I can remove the jumper and it stays running. Either way if I plug in the AFM the engine immediately stalls. Apparently my AFM was not the problem, is it my COR or something else?
This sounds like a tough one for sure. It certainly sounds like a fuel delivery issue. You need to verify that the fuel pump is operating when it should, and if not, it may be a bit of research to find out why. The service manual I posted in the description of this video has an enormous amount of helpful information, but it can take a while to find it and sift through what actually matters. Good luck!
maybe a relay for fuel pump...i bought a tester..but havent used yet. My relays are 34 years old...
great video
Thank you!
Thank you sir, great video
You're welcome!
Thank you I have a problem with my car right now it's running to rich any hope
Well, I certainly hope you figure it out, and maybe this is a good starting point. Also, I have a video about the fuel pressure on these motors as well, which was causing mine to run too rich.
good vid
Thank you!
I am facing a similar issue. However, my engine starts slowly then slowly dies after ~40secs. I suspect the VAFM is not turning on the fuel pump. I confirmed my suspicions by putting a rag in the intake to hold the flapper open. Then checking the output voltage on the COR relay. When the VAFM is open it is supposed to send power to the output of the COR. This did not occur. Additionally I checked the E2-VS terminals while moving the flapper. The reading were within the 20-1200 ohm range, however it would ready infinity at certain points. I think I need to do what you did and clean that black strip. What was the best way you found to remove the silicone from the cover?
Cleaning the strip sounds like it may help in other ways, but I'm pretty certain your issue is instead with the E1-FC terminals, which are actuated by the "stop switch" I refer to at 2:01 in the video. Test the output from FC-E1 (the furthest left two terminals). The output should be infinity at rest, and zero when rotated at all. This is what commands the fuel pump to operate when the engine is running, and after the key is released.
If the test fails, I would open the AFM, and clean the contact pads on that spring switch with some folded sandpaper, similar to how you would clean the points on an older ignition system.
I scraped the silicone out mostly with a sharp knife and a small flathead screwdriver.
I opened it up and cleaned the strip until the resistance was normal. I did notice a scratch on the gear at the base, it looked like the contact made it. Unfortunately I didnt touch it for fear of ruining the surface and sealed the unit. The truck now runs great, but when i depress the gas it imediately dies.
Though I would update, revisiting this video because of another unrelated issue with the VAFM. Anyway the culprit was the COR Relay. Water got past the radio antenna and dripped into that relay. It is located in the passenger kick panel. I relocated the new one closer to the firewall and it fired up and runs good.
@@codyhinds683 Thank you so much for the update! I had water in that area as well and it ruined the horn relay... I made a video about it.
nice video
Thanks!
Shane, great video. Crazy question but how did you get the connector plug removed? I noticed it has two small clips on each end, don’t want to break the plug. Any thoughts?
Very carefully... 🤣 No seriously, I don't remember off the top of my head, but I was super careful to not break them, I know that much... Good luck!
if plastic breaks, or cracks I used JB Weld SuperWeld light activated instant glue on the broken tab.. I watched a you-Tube about this method for fixing broken old engine bay electrical connectors. Its still removable after the repair. I had success with the water temp sensor plastic connector tab crack repair
Dude your a genius so you you just cleaned it?
Well, I don't know that I'm a genius, but yes, I just cleaned it. 🤣
What did u use to clean the contact area? Contact cleaner? Q-tip?
Could this part cause the truck to not even start if it were broken ?
There are a handful of ways it could be "broken", so depending on the issue with the unit, possibly.
Hey I have a 1991 4runner 3vze, and I’m looking at connector that goes to the E2 slot and I’m missing the female metal connector, is that normal. It looks like I’m supposed to have 7 wires in there but I only have 6. Where does the E2 connector goto? Thanks for the video.
E2 is a ground pin. I have no idea why it would be missing, but if you just use a ground in place of it, your measurements should work.
Great thanks I’ll give it a try.
I have a 1991 Toyota truck. Starts fine. Idles fine in park but when I put it in gear it idles rough and wants to shut down. Any thoughts?
What is your idle speed set at? Have you tried turning it up a little? In case you're not sure how, I briefly address where to find the idle speed screw on my 3VZE timing video
Wanted to hit you up for any ideas... (your videos BTW have helped me to learn about all this and are great...but I have this...(93 / 3.0) so at idle you can very faintly hear a hiccup every so often - if you throttle up to say 1700rpm - it will drop 200-300 rpm then jump back up - over and over. --------..--------..--------..--------..---- that sort of thing. If you hold the throttle higher (3000rpm) it just runs rough. Could this be fuel pressure related?
To date the following are all new: fuel pump, fuel pressure regulator, O2 sensor, all vacuum lines, plugs, wires, cap, rotor, distributor, ignition coil, igniter, intake gasket, had the ECU all tested OK.
Any ideas? Please... lossing my mind over this... ;)
Unfortunately there are an awful lot of possibilities, but it sounds like the computer is receiving conflicting information somewhere and is doing its best to compensate. I wouldn't guess it's ignition related, although it sounds like you changed most of that already anyway. Was it exactly the same before and after you changed the O2 sensor? Is the engine temperature sensor reading correctly? Did you measure the fuel pressure? The throttle position sensor would probably be the next thing I would actually verify is working and adjusted properly. There is a lot of information about how to do this in the maintenance manual I have linked in the description, and if that yields no results, check all the readings on the AFM. Good luck!
@@shanesgettinghandy Thank you sooooo much for taking the time to reply. I will keep digging and post when I find the answer. Tried multiple tps units and dialed them in with no change, and the afm tested correctly on the bench. And seems to move correctly when running.
Does seem like the exhaust is pretty thick. Maybe a bad new o2 sensor?
@@chartlights That's not a bad guess, and quite possible. That kind of stuff happens more often than it should, especially with aftermarket parts.
The stuck the probe in the exhaust today, came up with too much of a fuel mixture. And you can smell it in the exhaust as well. Would the maf be the problem?
It's certainly one possibility, but unfortunately it's not the only thing that could cause a rich mixture problem. A bad O2 sensor, temperature sensor, or a handful of other things could also cause this.
Also, check your fuel pressure. I will be making another video related to this very soon.
What did you set the voltmeter on when oming it? Like 20k 2k? I'm confused on which setting is the correct one. having issues with my 4runner think this may be issue
2k would be the most correct setting for this measurement. The idea is to set the meter to the next number higher than you predict you will be reading. 200 would be below the readings, 2k would be above, so 2k it is.
@@shanesgettinghandy right on thank you
So I think my 1993 t100 with the 3.0 is in need of a air flow meter, it drove fine but then died and thought it was out of gas. Filled it with a hand pump and only took half a 5 gallon tank before spewing on the ground. Fine. Fixed the vacuum leaks by replacing all 10 feet under the hood, even tightened the air box silencer on the bottom portion. Question is, can a faulty afm cause the fuel pump to keep priming? It wasn’t doing it until after I went for a drive, key on off it just keeps recirculating thru the fuel regulator. I found a broken square piece of a tab as I removed the box, didn’t think nothing of it, even the idle improved before and after normal op temp. And the flapper inside is very noisy, like it’s clapping at Sunday church. Very loud. Is it supposed to be that loud? Also the tube that goes into the box from the reed valve is very gurgly. Not finding any real answers and been scouring the Haynes manual and old threads.
Measure the resistance between E1 and FC. When looking at the connector it's the left two pins. With the plate closed, sitting normally, the ohmmeter should read infinity. If the AFM is twisted open manually, it should read continuity. This is the fuel pump cutoff switch, and is the "stop switch" I refer to at 2:01. If the readings are correct, the issue is NOT the AFM, but crucially, if the measurement reads continuity when you are not manually opening the AFM, you have likely found the culprit.
And if that all measures correctly, check the Circuit Opening Relay next.
htftp.offroadsz.com/marinhaker/programi/toyota/Engine/3VZ-E/96circuito.pdf
I will check on that in the morning, thank you! But is the flapper supposed to be click clacking like crazy? Only if the AFM is bad right?
@@rexmedina4561 Without actually hearing it, I can't say for sure, but if you listen to mine operating in the video, and yours sounds different, there is likely an issue.
Does anyone know where the INTAKE AIR TEMPERATURE sensor is on this same vehicle? My error code says there is a problem with it, but I don’t know if it is incorporated into the Mass Air Flow assembly, or what.
Yes, the intake air temperature sensor is inside this assembly. To verify the integrity of the sensor, check the resistance between pins THA and E2 on the meter. Using the table in the service manual you can figure out if the resistance is within specifications. If not, you will need to change the sensor. If so, it is either connector, wiring, or computer issue. Use this information: htftp.offroadsz.com/marinhaker/programi/toyota/Engine/3VZ-E/92volumeai.pdf
Another question - I bought a new AFM. But when I install it, he truck only runs for a few seconds, then dies (It seems like I smell fuel). If I install the old one, it starts immediately and does not die. I am confused now. Is it necessary to somehow reset the ACU to the new AFM, or something like that? (I tried disconnecting the battery for a while, but it made no difference). Thanks for any ideas!
@@jf8461 Sounds like the fuel pump cutoff switch is bad on your new AFM.
I have a 90 3.0 and runs great when cold but after warming up and driving sometimes it’ll die if I’m not accelerating, just idles rough and dies? Any ideas on what I can do? Would doing this help?
Is the check engine light on? If so, did you check the codes?
@@shanesgettinghandy nope, no lights, everything seems to be fine but sometimes it’ll turn on and idle kinda hard like it’s struggling to get air or something and then dies and I have to keep pressing on the gas pedal in order for it not to die
@@henryanaya8459 There are about a thousand things it *could* be, but the first thing I'd suspect is the EGR system. Warm up the engine so it is showing symptoms, then pinch or disconnect and plug the vacuum line to the EGR valve and see if the symptoms go away.
Im currently going through this with my newly built heads 93 4runner, warms up good then idle goes to 500 rpm and black smoke comes out exhaust. Runs ok with a little bit of roughness.
Where can I find a link to the info you used? Thanks.
ether3al.com/FSM/93fsm-mobile/
@@shanesgettinghandy Thank you!!!
Great video btw. I can not get that chart to load, but I can get the manual to open. Where do I navigate to get the ohm chart? Or if you have a PDF
How's the rig running?
All good!
Would this work on a 94?
For sure! 91-94 at least.
It will work for any 4Runner, Pickup, and T100 that have a 3.0L 3VZ-E
Im having a issue right now where itll start, run for about 10 seconds and then sputter and die, took that mass air flow metre off, cleaned it no change unless i manually control the potentiometer in there then i can get it to run. I checked it with a ohm metre and it seemed to be within spec but as soon as i let off the potentiometer go it dies. Anymore insight would be awesome. Ive been struggling with this for about a week and have found next to nothing on the internet. Thanks
Does it run okay if you just unplug the AFM?
@Shane's Getting Handy no, it dies right away and then wont start unless its plugged in again.
This sounds a lot like the problem I am currently having with my 91 truck (3.0L). The old AFM tested out of spec and not a smooth transition in resistance, so I bought a new AFM. The engine started quickly (with the new AFM) then sputtered and died. I tried a few more times with similar results. There was a noticeable gasoline smell, like it was flooded. Sill troubleshooting it.
@J F i had found my issue. I turned out to be the fuel pump. My best advice would be use a fuel pressure test, there is a 19mm bolt that connects the fuel line to the fuel rail on the drivers side. Thats where the pressure tester goes in. If theres no pressure hook up at 12volt battery to the fuel pump plug and then test the pressure. What happened with mine was the brushes had worn down the commutator so far that the springs that push the brushes against the commutator had run out of spring prsssure so it would make contact only sometimes and momentarily. Hence why id run for a while and then die. Hope this helps.
Fun.
Yes!
Where do you get these documents man
it's in the description my guy.
1st
Yep!