High cruise egts, fine under wot

[mavisky]

Okay here's the setup.

14b
510cc injectors
Aeromotive regulator (base of 45psi with hose off)
3000gt vr-4 pump (180lph no re-wire)
maft v 2.03 or whatever
3" maf from grand am v6

I have my maft in blow through setup and its set for 510cc injectors. My hi fuel trim is right around 100, mid and low are 130+. My maft is adjusted to richen up the mid throttle section, idle and base are left alone.

Lately the car is wanting to cruise at 1500 degree+ at 75mph, but if I go wide open the egt's drop to about 1400 or less. When letting off the gas the car bucks, worse than it did with the stock mas and vented bov. O2 trims are around 100 at cruise, light throttle sends it lean (even though I've corrected rich) and wot brings it to the rich side. I intend to clear the ecu and check for any sort of leak in the IC piping. I'm also hitting fuel cut at only 15psi on the 14b right now. I know its cold right now, but this seems a little extreme. I can normally run 20psi even in 50 degree weather. The car also seems to be stumbling and fumbling under boost now, not the smooth acceleration I'm used to.
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[2-0turbo]

Sounds like a faulty probe or an ignition problem with the cylinder you have the EGT tapped into. At part throttle operation, you cannot do damage from running too lean. It will start running crappy and the mixture will be too lean to light. Your best fuel economy is just a bit rich of where it starts the "lean burn hesitation."

You might have a boost leak too. But being that you are blow-through, that limits where the leak can be. I'm kind of stumped. You fuel trims of 130+ definintely indicate you are too lean though.

 

[mavisky]

Sounds like a faulty probe or an ignition problem with the cylinder you have the EGT tapped into. At part throttle operation, you cannot do damage from running too lean. It will start running crappy and the mixture will be too lean to light. Your best fuel economy is just a bit rich of where it starts the "lean burn hesitation."

You might have a boost leak too. But being that you are blow-through, that limits where the leak can be. I'm kind of stumped. You fuel trims of 130+ definintely indicate you are too lean though.

The ignition idea keeps coming to mind to with me as well, I guess I'll check the plugs and base timing and go from there.

 

[project_tsi]

Bringing up an old thread Kyle, but did you ever get this figured out? If not, is your EGR blocked off or capped off ? If so, that can cause high cruise/ part throttle EGT's.

 

[mavisky]

Reset the ecu, did some more tuning, reset the base timing, changed plugs and it went away. Still ran around 1500 though at 3000rpm +, oh well. New 650's are in now and I'll be using a keydiver chip for those.