Fuel Trim Imbalance Case Study, presented by John Thornton
2024 ж. 18 Мам.
32 215 Рет қаралды
Within this fuel trim imbalance case study, John diagnoses an 07 Ford F150 5.4L that misfires badly to the point where it stalls at idle. This is one of many case studies from our “Diagnosing Fuel Related Driveability problems with Scan Data” video. The full video can be found here:
automotiveseminars.com/produc...
Wow, the shop said they detached the cat and no change. I've seen way too many videos where technicians tend to believe a little bit of what other people have said they have done but somehow it comes back to that first suspected issue that ends up being the problem, never trust what other people say and do your tests. The IAT sensor tip is a great direction for checking backpressure, that is a new one for me, thank you for the tip.
The scan tool is the first thing that should have been hooked up
I have been reading Mister Thornton articles in automotive magazines for years , if I am not mistaken i think he wrote an article on a Nissan maxima many years back with a misaligned crankshaft flywheel . That said after reading that article i was able to land a good job at an Asian automotive repair shop because at that time no one where i live could have figured it out . This Man is Legendary those who have the chance to learn from this man....... it will only be you that would be the bottle neck in your automotive future with his guidance .
I am lucky to be one of those, tanks John. 👍
For anyone still reading comments on this video: If the O2 sensors are easy to access, I wonder if it would have been more efficient shop practice just to screw in a pressure gauge and compare the banks this way?
5 STAR VIDEO , EXCELLENT DIAGNOSIS .
Watching it again ! This is GOLD !!
Thanks for sharing... Cheers.
Brilliant. Thank you.
Kudos to U Sir
Great tip thank you for sharing.
great teacher
Fantastic tutorial ! Thanks !!!
Excellent training mr John
Very interessting Video, thanks and all good for you, John.
thank you. very helpful
Great video !!! Thanks
Interesting, thanks so much Mr thornton 👍
Great video John! Hope to return to your classes soon! Take care sir, hope your doing well.
Great explanation, you must reset the fuel trims & drop the exh simultaneously if your going to check for a restricted exh/cat that way, the learned fuel trim wasn't going to let that engine run very well. I do see lots of cam timing problems as well causing similar issues.
Great 👍
Good for learning electronic controls being old school would been using mechanical gauges vaccum compression and exhaust pressure, oh never assume previous Diagnostic been their more often than needed.old dog learning new ways.
Nice
Excellent video. Just curios as to why on 3.0L and smaller engines the grams per second compared to liter size of the engine does not apply?
That makes sense especially if the entire bank has a problem.
Am I the only one that noticed the MAF breakdown was for a 6 cylinder engine when he said in the beginning that it was a 5.4 V8?
Hey buddy, hope you are well.... Brian Hammond
2008 Ford ranger V6 vulcan engine . LTFT Bank 1 was running negative -.8 at idle , would not change. LTFT on Bank 2 at idle was 9 percent. Drive down the highway both long term fuel trims were within acceptable limits, but press more on gas pedal #1 LTFT got more negative and # 2 LTFT got more positive. Checking the number 1 catalytic converter oxygen sensor B1S2 with the truck fully warmed up , it was found the sensor was exactly duplicating the upstream sensor, switching from .2 to .8 volts. Number 1 catalytic converter was obviously no good and partially obstructed as well.
At 10:00 would global mirror dedicated? or is the substitution not allowed in global?
Good video. I have the issue with my 98 4.3 S-10 and everyone says what the las guys says is "Cloggged Cat, Bad Fue Pump, Bad Spider injectors, bad 02 Sensors etc" yet I have replaced allll oofff thoseee.
Same issue with fuel trims bank to bank? Be sure to reset trims after detaching the cat.
Vacuum or exhaust leak?
What's the difference between the PCM operating in closed loop with a fault vs open loop? If it's no longer listening/responding to the O2's input and just using stored values, isn't that just open loop?
Bloody interesant, 😮😮😮
So, when the shop stated that they dropped the cat. and it didn't change anything about the condition, were they blowing smoke up yours, did they remove only one side, and happened to choose the wrong one?
What I think happened, they did not do a KAM reset when they detached the manifold/cat. Just a guess but that's what probably happened.
Dropping the drivers side exhaust should have been all you had to do to determine the problem!
Why wouldn’t you first take out your temp gun shoot the manifold then the cat??? Just don’t understand why if you think you have a restriction in the exhaust why you wouldn’t check temperatures, IDN? Maybe to learn the newbie’s a long way to check exhaust restrictions Done…….. 30min of time waisted
i have watched dozens of these videos trying to figure out why my V6 is rich on bank 2 .. i thought i had found the answer here .. but my cat temps before and after are exactly the same on both banks .. i have high long term readings on bank 2 and soot builds up on the exhaust pipe ..
Did you do a smoke test?
Sounds like you way over complicated this
Another great USA repair shop fail ,
The country you’re from doesn’t have car shop failures?
increíble