J&JsTA

I have heard of others that say after their header install the car runs rich, and I seem to be running into the same situation by the deep black powder on my tips.

My question/confusion is how can this happen when at any other fuel trim other then WOT the ECM is suppose to read the O2 sensors and maintain a 14.1:1 A/F ratio no matter what????

I can understand that at WOT I may be running rich but most of my driving since install has been at regular speed limits and according to these web pages C5forum understanding O2 sensors that is not suppose to happen.

I have MACs with an ORP/O2simms and I am not using my MAFT at the moment.

<small>[ September 22, 2002, 09:28 AM: Message edited by: J&JsTA ]</small>

Predator

Headers lean out your LTFTs (positive numbers), and that number is added to PE causing a rich condition. WOT is not considered just 100% throttle, but 80% and up.

NoGo

iTrader: (2)

Changing your exhaust flow can change the percieved a/f ratio of the car quite significantly. Although your car may be running with an a/f ratio close to what it was before headers, your O2's are actually percieving a slightly lean condition. The PCM is attempting to correct a percieved "lean" condition and is adding fuel, causing your car to run rich.

This anomaly can be corrected by using a MAFT (mass aif flow transmitter) or reprogramming via LS1 Edit. Adjustments can be made to the Mass Air Flowmeter so as to eliminate the adjustments (LTerms) that the PCM is making to correct for the percieved "lean" condition.

Good Luck
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

JAS

<img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" />

Your O2 sensors READING's change because you MOVED the O2's further back and their (O2's) operating temperature has changed!

WIDEBAND

AzzHauler

iTrader: (3)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Predator:
<strong>WOT is not considered just 100% throttle, but 80% and up.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Almost <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> . There are tables that tell it how much tps to activate PE mode. RPM dependent, and possibly gear dependent too.

NoGo

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JAS:
<strong> <img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" />

Your O2 sensors READING's change because you MOVED the O2's further back and their (O2's) operating temperature has changed!

WIDEBAND</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"><img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" />

Any changes to the exhaust flow are going to alter the operating temperature of the O2 sensors as well as the percieved readings. This isn't something that happens just from relocating the O2 sensors.
To insunuate that this only happens because O2's get moved is incorrect.

White_Hawk

iTrader: (3)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Predator:
<strong>Headers lean out your LTFTs (positive numbers), and that number is added to PE causing a rich condition. WOT is not considered just 100% throttle, but 80% and up.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What he said. THe MAF T can straighten you out for normal driving but you have to get a scan tool to see where you were at to begin with. LS1-Edit can also change the MAF transfer function to get you back.

-Geoff

<small>[ September 23, 2002, 12:07 PM: Message edited by: White_2k2_Hawk ]</small>