Horrible Lean Miss
Thread Starter
Staging Lane
Joined: Jul 2002
Posts: 82
Likes: 0
From: Houston
Horrible Lean Miss My friend and I just installed the Thunder Racing TR224, 114 camshaft in his 98 SS. The car idles rough, as expected, and has random misfire codes, as expected. We know the car needs to be tuned to see all of its potential and help with driveability. Before it is taken to the tuner though, I need to know why it is exhibiting an ultra-lean condition at idle. The plugs are bleach white, and it runs so lean that it does begin to miss. The O2 readings at idle are .89v bank A and 1.1v bank B. What is the deal? Also, the fuel trim keeps setting itself at +25. Is it trying to lean itself out some more, or trying to enrich itself? Help, my friend is becoming disgruntled and I'm afraid that he is becoming jaded about Hot-Rodding his LS1.
TECH Addict
Joined: Dec 2001
Posts: 2,298
Likes: 2
From: new england
Re: Horrible Lean Miss Could you have vacuum leak or exhaust leak from air tube connections? This is where i would start, is your idle speed set correctly?Does car restart ok after hot soak? If none of these how about damaged ignition wire or spark plug from cam swap?
<small>[ September 14, 2002, 07:38 AM: Message edited by: LS1derfull ]</small>
<small>[ September 14, 2002, 07:38 AM: Message edited by: LS1derfull ]</small>
TECH Apprentice
Joined: Mar 2002
Posts: 357
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From: Newfoundland, Canada
Re: Horrible Lean Miss If your ltrims are at +25, then the PCM has gone as far as it can in trying to correct the lean condition and can't go any further. So to answer that part of your question, the PCM is trying to richen the mixture but has reached the limits of it's ability to do so.
<small>[ September 14, 2002, 07:55 AM: Message edited by: BillWS6Formula ]</small>
<small>[ September 14, 2002, 07:55 AM: Message edited by: BillWS6Formula ]</small>
