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Old 03-03-2012, 01:20 PM   #7 (permalink)
drmiller100
Master EcoModder
 
Join Date: Dec 2011
Location: Boise Idaho
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Quote:
Originally Posted by briogio View Post
Is it true that once the engine light goes the engine goes to a default (rich), setting?, because my emissions are REALLY bad.
short answer: Usually.

Longer answer: CEL means computer says something is wrong. If something major is wrong, then your statement is correct - ECU goes into "limp mode", runs plenty rich, emissions go up, MPG goes down.

Sometimes the computer says something non critical goes wrong - classic example is the computer detects the gas cap is loose, and the evap system has a leak. The computer throws a code, and lights up telling you to tighten your gas cap, but continues to run efficiently. Off the top of my head, the only other examples are an inefficient CAT and no flow on the EGR and transmission problems - computer runs correctly but throws a code.

Every other possibility (and there are hundreds) the ECU goes into limp home mode and burns gas and makes emissions, possibly ruining your CAT costing you LOTS of money.

Send me a PM with where you live and I'll help you find a good tuner in your area to help you troubleshoot this.
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