what would cause this? datalog errors, running lean. - Third Generation F-Body Message Boards

tpi90rs · 07-18-2009, 01:07 AM

everything has been replaced, think of it as a new car. heated O2. 165 ecm with 1989 bin

my car's running way lean, BLM around 155-160.

when I datalog using winALDL, the little box at the top flashes red with low numbers with an occasional "green 25".
My O2 reading will vary from .004,.45,.800 at idle and with throttle. The sound of the engine at idle sounds even, with a slight but not full miss in a cylinder or 2(assume from it being lean).

would a bad ECM cause this? I had the EGR temp switch wire plugged into the O2 sensor on accident resulting in voltage being fed up that wire wich shouldn't have.

I have no way of know what caused this because I just built the car. It isn't like "it was running, and then this happened."

This ad is not displayed to registered members.
Register your free account today and become a member on ThirdGen!

tpi90rs · 07-18-2009, 01:19 AM

also, no thrown diagnostic codes and the car idle hunts at startup when cold. 500-1500rpm.

Drumer919 · 07-23-2009, 11:07 PM

Is it actually lean though?

tpi90rs · 07-24-2009, 09:32 PM

I think so, I don't know what other thing to go by than the BLM. The fuel pressure is turned up a couple psi over stock and turning it up to around 48 psi doesn't change the way it runs.

buwamd · 08-21-2009, 08:47 PM

I don't know if you are running headers but one way I check for rich lean is header temperature, get a hand held lazer temp meter and point it at the header, if the temp is over 400 degrees its probably lean. you can also check for problems this way for each individual cylinder. hope this helps good luck

tpi90rs · 08-25-2009, 10:29 PM

it was the fuel pump, it had pressure but must have not had "flow". The fuel pump crapped out 500 miles later and the new pump fixed the problem.

The $200 "performance" fuel pump had 3000 miles on it. Walsbro. needless to say I'm $200 pissed