Car has MAF, pretty much all bolt-ons and it idles at around 15.6-15.8 average. I then take a good 5-10 minute drive to log. By the time I get back, park and let it idle more it had managed to cruise and idle at 16.5+ AFR. So basically it idles lean then slowly gets leaner. Also I can say that if it's a cold start it will idle rich then slowly get leaner as it warms up and starts idling lower.

- I've checked and double checked for exhaust leaks, none.
- After I did a headgasket/studs install and turbo rebuild on the car, I fixed boost leaks. Had 4 of them. Can't hear or see anymore using the boost leak tester and soapy water.
- Injector scaling for PTE 880's is already very close.
- I swapped to a backup front o2 sensor and I didn't get different results.
- I also bought and installed a replacement AEM wideband sensor and the results again were the same.
- It is using an Omni 4 bar map sensor that is scaled and logging boost identical to gauge reading.

I wander if it would be worth buying another map or maf next. Is there something else I am missing to try or look into first. Coming on here really makes me feel dumb. I could sure use some more minds on this one. Thanks fellas!

 

If I drive it for a little while or do a pull or two it starts to run so lean that the wideband reads 0. I also disabled the front o2 and put it in full time open loop and it still idles lean and it still eventually starts getting super lean. Seems like something the computer is doing to lean afr's. Any ideas are appreciated!

 

What are your low and mid fuel trims? What is your scalar and latencies as well as fuel? Is your wot lean too? Check your fuel pressure and listen if your injectors are firing.

It could be your injectors, fuel pump, scalar, latencies, etc.

 

Turned out to be EGR or Fuel Pressure Solenoid systems since both are deleted on the car. Disabled both I can drive for long periods of time now and it never starts to go lean.

 

I thought the problem was fixed. It is back now. I am at a loss. It gets leaner and leaner.

I did notice that when I unplug the MAP sensor it doesn't run differently at all... WTF?

I also unplug the IACV and it doesn't run differently... WTF again?!

When I unplug the MAF it idles rich and poorly.

I have tried Open Loop, Closed Loop, injectors were previously scaled and that is what I have been trying to perfect, but I can't get to that point.. I tried different values on the scaling for kicks around what that latencies were previously scaled to and it doesn't make a difference.

 

I can let the car set for a day or two and then go cruise and wot fine. The next day it starts getting lean as it idles or I cruise around. It's random. The fuel pressure is 100% ok. When it reaches its super lean state the car still idles and cruises fine and I park it as soon as I can find a spot. The injectors must be firing.

 

It sounds like fuel is ok. It doesn't idle rough when it's lean?

In order to help I'd need to see your WB readings, fuel trims (low and mid) as well as your o2 sensor feedback (STFT) and O2 volts in evoscan. Log an idle when this is happening. Inj Pulse Width would be good too.