The Trainer
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- Опубликовано: 2 июл 2024
- Join Motor Age in this episode of “The Trainer” with Technical Editor Brandon Steckler as he demonstrates how to use the Autel MS919 scan tool to not only identify an intermittent misfire but also determine what the cause of the misfire is.
In this video, Brandon describes the combustion process of a spark ignition internal combustion engine. He explains how an intermittent misfire affects the exhaust gas and how one appears in the eyes of a heated oxygen sensor and/or a wide-band air-fuel ratio sensor.
Through the monitoring of a few basic OBDII global PIDs, Brandon quickly and easily determines the cause of the misfire. The analysis can be conducted right from the driver’s seat without ever opening the hood and can easily point to an ignition fault or an injector fault. It’s all about “chemistry” of the catalytic converter.
Tune in and find out how the Autel MS919 can use this technique to take your diagnostics to the next level.
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I liked that....great analysis....very well explained....finding myself more learned on the subject after going through your very concise, well explained and presented video
Thank you!
Another great tutorial!!Thanks.
Just to add my experience in a spark misfIre conditions I’ve seen some cars go into default strategy and disable injection on a spark misfire cylinder. So both O2 data PIDs will show lean mixture.
For sure!
I first learned about this technique reading an article by Mr. Mark DeKoster in May 28, 2013 Motorage magazine. He also adds to the pids the STFT. Nice refresh. Great technique to make a first judgement of a misfire problem if you have lets say a V6 european car where everything is buried under many plastic parts and intake manifold and just the disassembly alone would be 1 hour.
Is that magazine good with troubleshooting techniques? thanks
Yes, MotorAge Magazine is chock-full of troubleshooting/Diagnostic techniques.
Thank you 👍👍👍@@brandonsteckler3417
Can anyone get the magazine?
Very informative video!
Thank you!
As everyone else stated, very well explained Brandon! Great tech tip. Thank you!!
Thanks, Spiro!
Another good delivery. Thank you Brandon.
Thank you!
Appreciate the information and the video B. Thanks again. Fuel trim diagnostics are very helpful to quickly see what's happening in the combustion chamber.
Thank you!
Got a intermittent misfire po302. Did all the swaps. Next is compression and leakdown
Excellent tutorial, thanks.
Thank you!
Great video, and very informative like all of your videos.! Thanks again Brandon..!
Thank you!
Very good presentation and analysis.
Thank you!
Great video as usual. Thank you Brandon.
Thank you!
Tremendous tutorial !
Nuff’ said . Seriously ! Thanks mate 👊🏼🔥 .
Excellent, good information
Interesting. Thanks for the explanation!
Thank you!
Very well explained and display of the data captured by the Autel and the description of the faults you created. Awesome how you can clearly see the difference in the two different types of misfire causes, the no spark shoots the secondary O2 upwards due to fuel "blocking" the oxygen sensor from "capturing" the Oxygen and the no fuel misfire having no fuel to "block" the Oxygen reaching the O2 sensor, shooting the reading downwards, and "capturing" a higher level of it, conversely deeming the reading "lean"
So much in-depth information from such a "small" scan data capture. Thank you for sharing as always!
You almost have that, correct…
The lack of spark misfire allows fuel to enter the catalyst. The catalyst will use the remaining oxygen internal to itself to catalyze the fuel molecules. As a result, almost no oxygen, is left over to leave the tailpipe. This result in a very high rear O2 sensor signal.
@@brandonsteckler3417 thanks for clarifying, always looking forward to learning from you.
Thank you!
@@brandonsteckler3417South Main talks about this in a comment on Royalty Auto Service's most recent video. In his opinion, you can only use FT to distinguish between an ignition or fuel related misfire if the vehicle uses the downstream O2 in its FT adjustment for the reason you mentioned.
However, looking at the live data and comparing the response of the upstream O2/AFR and the downstream O2 during the misfire can clue you into which type of misfire you have, again bc of the mechanism you described.
That was awesome!
Thank you!
Great Job! Thank you
Thank you!
Great video! Thanks!
Thank you!
nice work !!!
Thank you!
It’s my pleasure, honestly
Great video thanks alot
Great job
Thank you!
Great video marvellous what you can see using 2 obd pids x
The best 👍
Thank you!
I saw this technique in the past, but it was before scopes were used a lot.
This was a scan tool plotting graphed data(no scope used).
Yes and as such , you noticed the graphs are kind of weird shaped. If you used a freeze frame oscilloscope like a picoscope, you would get much crisper and reliable graphs. The refresh rate on scan tools is actually extremely poor compared to a good freeze frame oscilloscope where you will get clean graphs and not such odd shapes.
Saved to my "diag" folder
Wonderful, thank you!
Awesome technique, thank you for the video. 🤜🤛
Thank you!
That was good
Thank you!
Great video !! I was also wondering could you also monitor other parameters and come up with the same diagnostic conclusion of which cylinder is misfiring ? I was wondering , first use an ignition coil firing event from the #1 coil as a cylinder firing reference (scope trigger) , monitor the Ignition Misfire counter PID on a graph, monitor the RPM PID on a graph, when a misfire occurs - shouldn't the RPM graph slope down due to RPM drop and use the Scope triggering of #1 cylinder to determine by sequence which cylinder is dropping the RPM and also confirm while determining which Misfire monitor is counting up rapidly to identify the misfiring cylinder ? Thanks so much for your video !!
You have the right idea but remember. Ford utilizes that strategy in their “Power Balance Test”
Good job thanks
Hi , thank you for this informative video.
Regarding putting a jumper ground directly to the control side of the coil, how long can you keep it there, before it overheats the coil?
Also, what size fuse would you use on that jumper wire?
Many thanks, Joe.
Great question, and it should be something we are concerned with. However, this coil requires a high side driver to energize. By shorting the drive signal to ground, all I did was eliminate the control signal from making its way to the coil, preventing it from dwelling. In other words, this coil never turned on during that period of time. Does that make sense?
Great video Brandon. Is it possible to determine a mechanical misfire using the same method?
Simply adding graft data of the MAP sensor signal wire can help rule out engine mechanical faults
Some very good information here Brandon, Thanks Always like Autel scanners . Would love for them to put min-max feature on the pids thru
Thanks, James!
How does this work in a real shop environment.. would you let a car with a misfire get to normal operating temperature, to do this preliminary diagnosis and get some diagnostic direction, just to have the engine bay then be too hot to work on? Do you let the car cool off while you work on other cars? Would you perform this test if there was already a catalyst efficiency dtc stored? Lastly, is there any concern of causing damage to the cat while performing this testing? I suppose if the car was driven to you, the driver/owner of the vehicle has already cause way more damage than this test. I appreciate this video and will save it in my toolbox of tests to perform.
If you recall in the video, I took time to offer a disclaimer. I said “do not perform this type of test/experimentation, as I am only doing it as a demonstration”
With that, yes, this is very applicable in the real world. When we are trying to find the cause of an intermittent misfire.
When we can easily replicate a misfire, there’s no need to implement this test, because our normal diagnostic troubleshooting procedures will help us find the problem quite easily .
The catalyst must be laid off and functioning for this test to work. If you have a faulty catalyst, it will not work.
Brandon, thanks for the video. Are manufacturers still using transistors for ignition coil drivers or have they switched over to using MOSFETS in newer cars?
Pardon my ignorance….I refer to either of them as “transistors.”
I’m the eyes of the tech, it shouldn’t affect diagnostic approach.
To answer your question, likely “MOSFETs”
@@brandonsteckler3417 Thank you!
Nice video mate 😉 where can I get a video training? I want to be a Auto Mechanic 😅 thanks in advance for the reply 😉
What tools ? What you look ? And how you pointed out the binding part of the drive train that was slowing down the crankshaft to cause false misfire?
The tool being used is the Autel MS919. We are looking at the HO2 sensor signals to determine the oxygen content in the exhaust stream, indicative of a misfire. Nothing is binding in the in the drivetrain. I simply created a misfire by disabling an ignition coil and disabling a fuel injector.
I ask you this question because you said that a binding cv axe can cause a false misfire.
How a cv axel can throw a miss fire?
Binding can cause the crankshaft to momentarily slow down due to the mechanical link through the drivetrain.
Can't wait for the next training video
👍
QUICK-WITTED BRANDON STECKLER MOTOR AGE
Enjoy your weekend with all your family around you, Brandon Steckler Motor Age
From Nick Ayivor from London England UK 🇬🇧 ⏰️ 22:25pm
Thank you!
the same would happen if we had the classic sensor 02 instead of the afr in front of the catalyst?
Correct! however, the HO2S would dive low under lean conditions and high under rich conditions
@@brandonsteckler3417 so the strategy is on misfire from ignition problem we have 02s 1 lean o2 s2 ritch and from fuel problem o2s1 lean and o2s2 lean correct?
I’m sorry, I don’t understand what you are trying to say. Could you please reiterate?
A lack of ignition will allow fuel to reach the catalyst. A functioning catalytic converter will use all the oxygen to catalyze the fuel, leaving the rear O2 sensor high.
A misfire due to lack of fuel injection will leave excess oxygen in the exhaust room and drive, the rear O2 sensor low
@@brandonsteckler3417 sorry what you said i just meant i use google translate i don't know english...thanks m brandon that you answered me
You can’t tell if it’s spark or fuel on newer cars if the injector is turned off by the ecm? So looking at fuel trims wouldn’t help on newer cars??
The fuel injector will only be off with a cylinder specific misfire.
In this case, we are talking about an intermittent misfire that does not said a cylinder, specific misfire DTC, and does not shut off the fuel injector, even a newer vehicles
7:55 I guess this coil is of 3 or 4 wire design with a transistor inside and you're grounding the signal wire. But isn't this dangerous if a newbie is working and the coil is a simple 2 wire coil? Excessive current would pass through the coil and through the computer because the coil is saturated for longer?Newbie should be very careful. In my case i either disconnect the coil connector or use a spark plug tester if the coil is out of the tube.
Correct, three wire coil… You were also correct in that a two wire coil will overheat in a situation like that if it is energize for too long.
This is another reason I offered the disclaimer in the beginning not to perform this type of experimentation, unless you know what you were doing because you can cause damage, especially to a catalyst
It's NOT dangerous to the driver in the PCM only to the coil, because the coil will overheat and fail if jumper is connected for too long.
1. The drivers in the PCM for 2-wire coils are designed to allow higher currents compared to drivers for 3 or 4-wire coils.
2. The ignition coil circuit is protected by a fuse.
3. Most important: The driver in the PCM for a 2-wire coil will continue to function as normal (i.e. it will continue to pulse) while the jumper is connected. It will actually have less current going through it because the majority of the current will go through the jumper to ground not through the driver.
Please take my info with a grain of salt until Brandon responds, because I'm not a professional, I'm a beginning do-it-yourselfer.
I’m the 3 wire configuration I’m addressing, the signal wire pulled low will not hurt the PCM driver nor will it energize the coil. The transistor is not latched (not flowing current).
@@brandonsteckler3417 Sorry, I thought it was a 2-wire coil. Thanks!
No worries…I’m glad we got that cleared up
This is good information but I feel like it's not exactly practical.
Most intermittent misfires will occur in random counts, say maybe 5-10 fire cycles in a row and then back to firing normally. Watching fuel trim during this will not show much let alone point to a good direction.
A lot of times I see misfires that occur at complete random and engine load seems to have no effect. It's frustrating really
I found great success with this technique, even with intermittent misfires, only a handful at a time
Wouldve been nice if you could compare it on live data separately.
I don’t understand what you mean. That was live data. You saw me capture it when I created a misfire.
@@brandonsteckler3417 i meant if you could ran the live data for a min or so on each condition, i wanted to see if the pattern stays consistent on that same condition?
More correctly a no spark misfire
I'm sorry, I don't understand your comment. could you please clarify?
Why would you use the term "spark misfire" when there is no spark. I would think that calling it a "no spark misfire" would be a better call.
Correct… In the video, I said, I was going to refer to a misfire that lacks spark as a “spark misfire”.
I’m very sorry for any confusion. Thank you, Doug.
But now that I think of it there are differing scenarios in which there may be absolutely no secondary spark and those where the spark occurs but is shunted away throughi the insulation or through a ceramic leak. So dont let me interfere.
Did not here where the intermitant cause comes in
I do not understand. The entire video was about an intermittent misfire and how they reflect differently in the data from the heated exhaust gas oxygen sensors/wide-band sensors. Can you elaborate on where you have some confusion and I'd be happy to clarify.
P0300 only happens on one hill after cresting sometimes check engine light comes on and flashes a few times stays on for a few days then shuts off cannot feel the missfire.scan tool is showing everything normal
99 tahoe
Check Mode 6 and See if any Misfire Counters Occured.
nice. from Peru
Thank you!