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View Full Version : GMAF w/ Gen II translator help



3KVT
09-19-2013, 11:47 AM
So here's the basic break down of what's happening:
Car starts fine when cold, but hard starts when warm. It will turn over if I give it a little gas, but not without it. I have a constant idle, but my afr bounces around (I have the innovate multi) and when I'm driving and I take the car out of gear, it sometimes will not hold idle and die. I have no issues under WOT, and I'm running about 16.5lbs of boost.
I have 16T's and supporting mods (i.e. bigger injectors, fuel pump(hot-wired), and a GMAF to name a few). Everything is getting proper voltage and fuel system is cleaned regularly, including filter. I've been told by more than one person that these issues are most likely related to the GMAF or the ECU. I'm praying it's not the ECU. The car was tuned at GZP, and while the idle afr was a little erradic, I was not having the issue with starting and maintaining idle after pulling the car out of gear. I have not messed with the settings that were set at GZP, and I can provide those later today if needed.
I'm wondering if I need to go back to a baseline and start re-tuning from there, or if you guys think the ECU could be the problem. I realize it's nearly impossible to diagnose things like this without seeing the car in person and tinkering, but any help would be greatly appreciated. If you guys think I need to start from a baseline, I'd like to know what those settings would be. I have found very limited info for this on the net, and most of the aftermarket settings for the GMAF I've found are for DSM's.

Thanks in advance!

mjannusch
09-19-2013, 12:53 PM
What injectors, and what are the values in your Cranking IPW table? When you say your AFR bounces around at idle, how far off does it get? It is normal to range from about 14.2 to 15.3 until all the fuel trims stabilize, which takes a fair amount of driving to get them all squared away. What are the current values for the fuel trims? Post a log of it idling after it has warmed up and include the fuel trims and MAF hz.

3KVT
09-19-2013, 04:07 PM
Unfortunately, I don't currently have access to a data-logger. I had a palm, but it just shat out on me about 6 mos. ago. The idle afr bounces from 12.2-3 up to 15.6-7. Not a normal range by any means. It almost seems like the ECU is trying to compensate, but can't for whatever reason and ends up going rich and then lean again. It never stays at 14.7 under about 2500 RPM's. Driving above 2.5k keeps it a lot closer to 14.7.
After the initial tune, I drove the car for over 2,000 miles and always had the idle afr issue, and yes, with the same range as mentioned above. It only recently started dying when I go to change gear, and again only recently began the warm-start issue. I had almost all of the gaskets and seals replaced at Ninja, and ever since then it has been acting up. I has since gotten worse steadily.

RC 450cc injectors.

Greg E
09-19-2013, 04:36 PM
What injectors, and what are the values in your Cranking IPW table?

I don't think this guy is running a flash ECU.

3KVT
09-19-2013, 06:43 PM
Factory reman ECU.

mjannusch
09-19-2013, 10:21 PM
Recently pressure tested the intake?

3KVT
09-20-2013, 08:10 AM
Recently pressure tested the intake?

Just had vacuum lines (have vac reduction done, so remaining vac hoses) replaced. Did a manual pressure test after I got the car back just to make sure everything was tight. Everything is good there.