stumble/hesitation on 2005 6.0 gas motor

NC-V said:
O2s should be switching above and below that .450 constantly between .1 and .9v Fuel trims will go to 0 when in power enrichment, which in that truck is most likely above 90% throttle, otherwise the LTFTs should be moving around +- 10 ish
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I dont think his tool has a fast enough sample rate. It's possible there's an airflow problem hence the low load.

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Too bad I'm not closer, I'd lend a hand.
 
whats the absolute hands down best way to look for a vacuum leak? Ive never had any luck with propane etc. What am I doing wrong?

this thing was driving great; rode it hard as can be doing hot laps (cut corn field). only thing is that I took a somewhat hard hit when I understeered on a turn and hit a tree. but I drove it two hours on highway after that no issue. bought it home, pressure washed it, put up, and now it stumbles. there has to be an answer.
 
Crank sensor re-learn?

I don’t know that it will fix it but it can’t hurt. That’s what was causing my random misfire it turns out and I just did the re-learn Thursday. No more issues.
The timing chain stretches over time, so the variable in timing is greater than what the computer is told is acceptable. A re-learn takes 30 seconds. Maybe running it hard was just enough to be out?
Again I don’t feel too strong that’s your issue, but anything I can offer to help I figured I would. I hate racking my brain over issues like this so I know how you feel.
 
Chuckman said:
whats the absolute hands down best way to look for a vacuum leak? Ive never had any luck with propane etc. What am I doing wrong?

this thing was driving great; rode it hard as can be doing hot laps (cut corn field). only thing is that I took a somewhat hard hit when I understeered on a turn and hit a tree. but I drove it two hours on highway after that no issue. bought it home, pressure washed it, put up, and now it stumbles. there has to be an answer.
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I dont think you are doing anything wrong at all! Most technicians spend between 40-60 hours a year in training, it's not as easy as it used to be.
Vacuum leak is also determined by data in terms of fuel trims and oxygen sensor voltages, a vacuum leak will result in negative fuel trims and low oxygen sensor voltage at idle and both will improve as the rpm increases. I think the biggest concern right now is the scan tool may have a low refresh rate which makes it difficult to document live data and analysis of the data is difficult without a graph in front of you. For instance when we analyze data we have the ability to see it on the scan tool screen, send it to our computers and also send it to other technicians for second opinions. I've attached a photo of a graphed oxygen sensor, as you can see looking at a numeric value, especially if it's on a scan tool which refresh rate is slow provides very limited data. There's just so many things that it could be, attempting to locate the needle in the haystack can be difficult without prior experience in driveability. Do you have any shops you could trust to take a look?
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^ no, theres not a soul down here in Charlotte that I would trust at all with this thing. theyd go wreck it in a hot minute playing with it.
 
Chuckman said:
^ no, theres not a soul down here in Charlotte that I would trust at all with this thing. theyd go wreck it in a hot minute playing with it.
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I actually have a contact in pineville that operates a shop. They run and extremely tight ship - I can assure you they would not disrespect your vehicle in anyway. I'm not sure if they would work on customized vehicles as the owner is a very by the book kind of guy.

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Anybody who tunes with HP Tuners or EFI Live will have the VCM Scanner software with their tuning software and it reads live data. That'd be a start, at least.
 
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