Lou Merrell
I'm Awesome
Do you think I have a vacuum leak?
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Problem on the 'limp' home yesterday.
- Thread starter Lou Merrell
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stutaeng
I'm Awesome
Not likely. I mean, you can check by doing a simple acceleration while simultaneously monitoring fuel trims. 1k, 2k, 3k RPM.
Case 1 is fuel trims improve with increase in RPM, then possibly a vacuum leak.
Case 2 is fuel trims don't really change. Vacuum leak is not likely...keep looking elsewhere.
Do you have live data or just freeze frame information? I would not say limp mode, just a severe driveability issue due to fuel trims/mis-fire, maybe both. 50% fuel trim. The ECU can't correct over 25% is what I've read. But you state A/F ratio is pretty close to stoichiometric ideal number (that's from your scanner, I assume?)...not sure what to say about that.
Case 1 is fuel trims improve with increase in RPM, then possibly a vacuum leak.
Case 2 is fuel trims don't really change. Vacuum leak is not likely...keep looking elsewhere.
Do you have live data or just freeze frame information? I would not say limp mode, just a severe driveability issue due to fuel trims/mis-fire, maybe both. 50% fuel trim. The ECU can't correct over 25% is what I've read. But you state A/F ratio is pretty close to stoichiometric ideal number (that's from your scanner, I assume?)...not sure what to say about that.
Vortec? Your fuel pressure is low.
Lou Merrell
I'm Awesome
5.7 vortec.
Yeah, numbers all over the place.
Yeah, numbers all over the place.
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stutaeng
I'm Awesome
The idle fuel pressure is a bit low, but given that one bank is seemingly running right, I would not concentrate on fuel delivery at this point. Fuel delivery problems typically affect both banks; fuel trims are usually within the same percentage of each other, and get worse as RPM increases.
What is the fuel trim for bank 2 at 2,000 RPM?
Edit: I just saw you initially posted idle and 1500 RPM fuel trims, and fuel trims got worse on bank 2. Based on that alone, you can eliminate vacuum leak, based on what I mentioned on my first post.
So I would be either chasing a mis-fire or an injector is not pulsing...
What is the fuel trim for bank 2 at 2,000 RPM?
Edit: I just saw you initially posted idle and 1500 RPM fuel trims, and fuel trims got worse on bank 2. Based on that alone, you can eliminate vacuum leak, based on what I mentioned on my first post.
So I would be either chasing a mis-fire or an injector is not pulsing...
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Yup. Misfire or failed injector(s).
Given that you have a misfire code, I'd be starting there. Is your scan tool capable of providing REAL misfire codes, and misfire counts for each cylinder, or does it pretend that all misfires are "random"?
Given that you have a misfire code, I'd be starting there. Is your scan tool capable of providing REAL misfire codes, and misfire counts for each cylinder, or does it pretend that all misfires are "random"?
Lou Merrell
I'm Awesome
Yeah, its time for the ol' mpfi upgrade, and while I'm in there, intake gaskets.
Lou Merrell
I'm Awesome
All my misfires are on #2,4, and 6.
I'll get some better live data tomorrow.
For a while now, the truck has had trouble firing up after having been driven.
Once warm it will stumble alive so I'm pretty sure my regulator has a problem also.
I'll get some better live data tomorrow.
For a while now, the truck has had trouble firing up after having been driven.
Once warm it will stumble alive so I'm pretty sure my regulator has a problem also.
Lou Merrell
I'm Awesome
New live data from dash command:
My poor truck....
I got you!
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My poor truck....
I got you!
You've got misfires on Bank 2.
Misfires cause the O2 sensor to report false "Lean" signals. Of course the fuel trims have gone way rich. The computer is trying to correct a faulty signal due to misfire.
Fix the misfire, the fuel trims will likely go back to normal. The trick will be to repair the misfires--is it fuel? Spark? Compression? Plugged exhaust?
Good luck with the catalyst. Misfire kills them, too.
Misfires cause the O2 sensor to report false "Lean" signals. Of course the fuel trims have gone way rich. The computer is trying to correct a faulty signal due to misfire.
Fix the misfire, the fuel trims will likely go back to normal. The trick will be to repair the misfires--is it fuel? Spark? Compression? Plugged exhaust?
Good luck with the catalyst. Misfire kills them, too.
