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post #1 of 10 (permalink) Old 04-03-2011, 06:57 PM Thread Starter
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Running Lean

I recently finished my sc install and it drives fine with a good afr until i let off the gas, than my car goes full lean and stays that way for about a min. Or if i sit at an idle the car is fine but will go lean at random than it will level out. I have no check engine light but i can feel my car is not running like it should and dont want to drive it running lean. I checked injectors, vaccum, and plugs. when i changed my plugs back to factory instead of a step colder the problem seemed to get a little better. Im thinking maybe get another set of plugs in the morning but without a CEL im not sure how to go about fixing this.


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post #2 of 10 (permalink) Old 04-03-2011, 07:00 PM
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Originally Posted by black09cobalt View Post
I recently finished my sc install and it drives fine with a good afr until i let off the gas, than my car goes full lean and stays that way for about a min. Or if i sit at an idle the car is fine but will go lean at random than it will level out. I have no check engine light but i can feel my car is not running like it should and dont want to drive it running lean. I checked injectors, vaccum, and plugs. when i changed my plugs back to factory instead of a step colder the problem seemed to get a little better. Im thinking maybe get another set of plugs in the morning but without a CEL im not sure how to go about fixing this.

Are you letting completely off the gas when it does that, or just backing off while still having the pedal pressed a bit?
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post #3 of 10 (permalink) Old 04-03-2011, 07:05 PM Thread Starter
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completly off and even if i press a bit it still stays lean so imagine im pretty far off the gauge. when i give it gas though it imediatly goes back to normal.


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post #4 of 10 (permalink) Old 04-04-2011, 03:14 PM
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That sounds fine to me. When you let completely off the gas the car should go into DFCO aka Deceleration Fuel Cut Off. Ofcourse its going to get lean since it turns the injectors off. Thats whats causing the crazy reading. As long as it returns to what it is tuned at when you get back on the gas it will be fine.
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post #5 of 10 (permalink) Old 04-04-2011, 05:20 PM
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Might be a dumb question, but you have your tune installed correctly and all that?

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post #6 of 10 (permalink) Old 04-04-2011, 09:26 PM Thread Starter
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I got my tune from trifecta and installed it without issue. I understand that it should run lean some but full lean (my aem afr wideband cant even register it) i was unsure of. Also sometimes at an idle it will decide to full lean and almost shut off (car shaking) but will even out on its own. I was thinking possibly i have a vaccum line hooked up incorrectly? I know I have the one to the throttle body correct but the little one on the intake and the bypass valve? Other than this I can't think of anything else. I have herd nothing but good about trifecta tunes so i highly doubt its a tune issue.


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post #7 of 10 (permalink) Old 04-04-2011, 10:40 PM
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Your Idle needs to be sorted out, your short term fuel trims are probably off which is causing the car to almost misfire when you are idling and lean out every now and then. What is your aft at WOT? and the does your gauge do dashes --- Like that when it is going lean? that is normally the signal it will give you when your car goes into dfco.

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post #8 of 10 (permalink) Old 04-04-2011, 10:57 PM Thread Starter
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at WOT I am around 13.7 to 15.2 which i would imagine is ok. Yes I am getting the --- and aparently this is normal which is good (this was my main concern). So my only issue now is the short term fuel trim causing idle inconsistancies. Any ideas on what would cause this? And thank you all for the insight so far!


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post #9 of 10 (permalink) Old 04-05-2011, 11:33 AM Thread Starter
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Update: just got a CEL code Running to lean


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post #10 of 10 (permalink) Old 04-05-2011, 05:34 PM
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You are running way to lean at WOT, when your pedal is all the way to the floor the leanest you should be running it 12.8, that is the max, most people only push it to 12.5... you can be causing some pretty bad damage to your motor, however, the numbers you posted up sound like your cruising afr?

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