Lean condition under acceleration
Thread Starter
Instructor
Joined: Sep 2002
Posts: 116
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From: Boise ID
Lean condition under acceleration
I seem to have a lean condition when accelerating. When the car is cold there is excessive pinging when the pedal is approx, 60%. After the car gets to about 145 degrees it goes away, mostly because I think the knock sensor is retarding the timing. I know I need to get a scan tool to do a better evaluation of the problem but for the time being I have hooked a volt meter to the O2 sensor and it seems to function normally during cruise and light acceleration but goes to 0 under moderate to heavy acceleration. Here is the weird thing and I can't decide if it is an electrical problem or a mechanical problem, every once and while it will run great, no ping when it is cold and twice the power as normal when it is warm. I have tried everything, ignition is in good shape, fuel pressure seems good, it is 45 @ idle and 52 with the vacuum line unplugged, a new front y pipe and cat installed. I have tried to find and check all the grounds. I wish I knew somebody else with an L98 so I could swap MAF sensors, I'm wondering if it might be going out. I'm really out of ideas; I look forward to any suggestions or ideas you guys have. 
Thread Starter
Instructor
Joined: Sep 2002
Posts: 116
Likes: 0
From: Boise ID
It is the stock chip. I have double checked and there are no vacuum leaks. I know that it is running lean; when I pulled the exhaust off to change the front y pipe the exhaust manifolds were very white. I picked up a new O2 sensor the other day but haven't had a chance to put it in yet. It really is baffling. It doesn't run really bad but bad enough that you know something is wrong. It really seems like when it goes into power mode it advances the timing but forgets about the fuel.
Thread Starter
Instructor
Joined: Sep 2002
Posts: 116
Likes: 0
From: Boise ID
I thought the same thing but the fuel filter is relatively new and I have verified that the car is not losing fuel pressure during acceleration. I wish I could find the answer to this it drives me nuts every time I get in the car. Any suggestions on a good scanner to get?
