I currently have an AEM Wideband installed to monitor AFR's. During normal part throttle driving the AFR numbers are normal hovering around 14.7. during WOT the AFR are normal until about 10 PSI of boost when it goes to extremely lean (maxes out my wideband at 17.0:1). I am currently using a Cobb AP and a MBC. when i unmarry the AP and remove the MBC (essentially returning it to stock) nothing changes. same issue at WOT. I figured out that if i reset the ecu with my AP or kill the power from the battery, that the car runs properly for one trip. ie. if i kill the power to the ECU and let it reset and hook it back up, crank it up it will run properly until i turn the car off. i have tried this with the AP married and MBC installed, and with it uninstalled and No MBC. this leads me to believe it is a sensor/electrical issue. i have ordered the Fuel Pump Relay, and cleaned my MAP sensor. i have checked my MAF sensor and it also looks good. there are NO CEL's being thrown during this process. i am still running the stock FPR and injectors. according to the logging in the AP the MAF sensor is working


so my question is, does anyone have any other suggestions on what i can check or what the problem may be? thanks.

 

Check your Spark Plugs!

 

check your spark plugs and your 02 sensors. sounds electrical or sensor related. gl with your search

 

What do you mean by it runs okay when you reset the battery? Does the car run normal AFR's after you've reset the ecu, but start running lean after you've driven it a distance? Is the car falling flat on its face when youre in boost? If your car is actually hitting 17:1 at any boost at all your engine would have no power, knock really bad and likely blow up. We need more info on how it was actually driving. Likely an electrical issue somewhere if it drives okay.

 

relay

 

after a reset of the ecu by disconnecting the battery or using my AP the car drives just like it should at cruise as well as at WOT. if i turn the car off for any reason and then restart the engine and drive it, it won't run worth a damn at WOT but will cruise around just fine. it has nothing to do with the distance as far as i can tell. the car will fall flat, and and start to sputter due to the very lean conditions only under WOT but drives find when at part throttle. the car looses power badly but is not registering any knock on the AP and is not throwing any CEL's.

 

Check your FPR hose on the engine. Mine popped loose when I accelerated in traffic. I had a huge spike of knock on the AccessPort (I believe knock retard jumped to 7.7) as the vehicle shuddered and my AFR's went very lean for a moment. I was able to make it home cruising with relatively normal AFR's, and the next morning when the car was cool, I checked to make sure nothing had popped loose. Sure enough, it was the FPR hose. I've since tightened it down with zip ties, and it seems pretty solid, though I may switch to some small hose clamps as a more permanent solution.

My car had pretty much the same symptoms, idled like **** at stoplights, and had a noticable loss of power at WOT with the AFR's shooting up. The AccessPort barely logged any knock at all during cruising and WOT after the initial incident, though it would still read knock at random RPM's. Thankfully I caught it pretty quickly, and hopefully no damage was done.

 

Before anything else, make sure to check and see if the fuel pump relay had been replaced.

Make sure to keep us posted once you have been able to diagnose the issue. This could be a big problem for us as well later in the future.

 

Fuel pump relay, FPR hose, LTFT Mid Switchover point.

 

First thanks for all of your input. just an UPDATE: I checked the
spark plugs, they are good.
FPR hose, I went ahead an replaced it thinking it may have split under foam part i couldn't see.
took it out for a test drive and still messing up.

the newer Blue Relay should be in tomorrow.

 

is this a stock tune?

 

i have an AP and it does it with the stock tune as well as my custom AP Tune. the Tune does not seem to affect it at all. that was the first think i tried was unmarrying the AP to see if it was still running lean under WOT on the stock tune as well.

 

well revert back to stock until you solve it.

I'm 85% sure it's the fuel pump relay

 

It does sound like it's the relay. Let us know if it solves your problem when you get the relay in.

 

swap your foglight relay for your fuel pump relay, why risk blowing up your engine for working foglights?