Lean at Idle

sleepydsm · 10-03-2008

My AEM o2 says normaly "---" which is max lean at idle, sometimes its between 18:1 and like 15:1. While cruising, the car sits at like 14.7 as it should.

Any ideas?

95talonracer · 10-03-2008

Mine does the same thing. Where is your sensor placed in your exhaust system? How far down? Mine is where the second o2 us and I am thinking of moving it up farther but you dont think that should matter since when they dyno a car its at the very back tailpipe.

4g63tcrazy · 10-03-2008

Wouldn't it make sense to have the car idle lean? Cars usually dont use up that much fuel just idling.

sleepydsm · 10-03-2008

I thought it'd be at 14.7...

My sensor is 36" away from the turbo outlet, per the AEM instructions, which on my 1g places it just behind the axel and between the crossmember. Perfect

dsm9sec · 10-03-2008

Quote:

Originally Posted by sleepydsm

I thought it'd be at 14.7...

My sensor is 36" away from the turbo outlet, per the AEM instructions, which on my 1g places it just behind the axel and between the crossmember. Perfect

Have you gotten your car tuned prior to installing the WB?

Better yet, are you on a stock ECU?

sleepydsm · 10-03-2008

yeah, stock ecu, pretty much stock everything else. Has a stock set zero'd out MAFT and stock 450s. Aeromotive AFPR and walbro 255hp. stock 14b also. stock 6 bolt kinda.

dsm9sec · 10-03-2008

Quote:

Originally Posted by sleepydsm

yeah, stock ecu, pretty much stock everything else. Has a stock set zero'd out MAFT and stock 450s. Aeromotive AFPR and walbro 255hp. stock 14b also. stock 6 bolt kinda.

Then I probably wouldn't worry about it. The stock ECU adjusts fuel trims as it sees necessary.

**Goat Blower** · 10-03-2008

Mine does the same thing, and it's not right. In closed loop, your a/f should hover around 14.7, that's where it's supposed to be. Mine goes lean and the idle drops to 900rpm and it stumbles. I haven't had time to mess with it, it might be the removed honeycombs on my maf, I'll find out soon enough.

**JET** · 10-03-2008

Sleepy, it sounds like your WB is probably getting too cold and not giving a reading any more. Mine used to do that at idle sometimes too. I was actually too rich causing the sensor too cool too much at idle. I can really see the problem with it being that far away from the engine, that is a long ways away.

dsm9sec · 10-03-2008

My WB is right where it sounds like Kevin put his. 1" behind the half shaft @ the center of the motor and mine didn't cool. I thought they were self-heated?

One thing I do know for sure is DO NOT put it right where the turbo outlet is if it's a street car. Mine burned up in 2 months @ that spot.

**Goat Blower** · 10-03-2008

Quote:

Originally Posted by dsm9sec

One thing I do know for sure is DO NOT put it right where the turbo outlet is if it's a street car. Mine burned up in 2 months @ that spot.

Yep, had that same thing. Put it in the stockish location and went through three sensors in 600 miles. I've been on this new one all year around 1500 miles.

Spyderturbo007 · 10-07-2008

Mine was doing the same thing and it turned out to be an exhaust leak. If you were running that lean, you would be maxing out the FT's and ending up with a Fuel Trim Malfunction (Bank 1) CEL, so it sounds like your exhaust leak is somewhere between the front O2 and the WBO2. Mine was a blown O2 housing to DP gasket.

**Shane@DBPerformance** · 10-07-2008

1Gs don't throw fuel trim errors, thats an OBD2 function.

Spyderturbo007 · 10-07-2008

I didn't realize that it was a 1g. Anywhere around here where you can find what vehicle people have? I'm new, so I don't know anyone and can't seem to find anything in anyone's profile.