Running LEAN

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Apr 17, 2006 | 01:10 PM

Manny Fresh

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From: San fernando,California

Running LEAN

I just changed my hole exhaust. I put my headers and put my LM and took of my cats. Can this cause ur car to run lean or could it be from a bad 02 sensor. What can I do 2 fix this because my car felt faster before i changed my exhaust.

Apr 17, 2006 | 01:23 PM

daryl2cb@yahoo.com

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From: Greensburg,PA

you will lose some low end with the headers, but you should be running rich, usually headers do that. I would look to a tune.

Apr 17, 2006 | 01:38 PM

Manny Fresh

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From: San fernando,California

I checked my super chip tuner and it said that- sys to lean (bank 1 and 2) it also says- catalyst efficiency below threshold( bank 1 and 2).

Apr 17, 2006 | 02:12 PM

bshell

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From: Newport News, VA

Quote:

Originally Posted by Manny Fresh

I checked my super chip tuner and it said that- sys to lean (bank 1 and 2) it also says- catalyst efficiency below threshold( bank 1 and 2).

Can you watch the O2s cycle in real time? They should oscillate low to high with the mid point being 400-500mV. If they are flatlining low, the pcm will assume you have a lean condition and will attempt to fix it by adding fuel. If it has to add >25% for a given amount of time, it will set the system lean codes. Since you have codes for both banks, I would lean more toward the O2s being dead.

Did you delete the rear O2s, or install sims? If not, that's where the cat eff low codes are coming from. With cats removed you should also disable cat overtemp protection (if you haven't already).

Apr 17, 2006 | 02:28 PM

MeentSS02

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From: Dayton, OH

Quote:

Originally Posted by daryl2cb@yahoo.com

you will lose some low end with the headers, but you should be running rich, usually headers do that. I would look to a tune.

Actually, headers cause you to run lean, but the computer compensates by adding extra fuel (seen in usually + fuel trims)...and since it does this, it dumps in extra fuel at WOT. Make sense?

I would bet that it is all in the tuning...my car is faster all around with headers, but it took the tune to do it. I only gained like 1 MPH and dropped a little more than a tenth off my track times after the headers went on. My car's computer didn't get along with them...it does now though