rich fuel condition

[SgtMarshal]

do you guys think not running a catalytic converter would cause a rich fuel situation? I installed headers without the cat and I've been running rich for a while. 2001 GTP

[97AutoXVette]

Not having a cat shouldn't cause the change really but the full header combination may be a contributor. I have usually heard of guys being on the lean side after a header install vs. richer. But could be different for your case. Are you seeing it happen on a wideband?

[SgtMarshal]

I dont have a wideband, I am assuming I am running rich because my aeroforce is showing 16.4 and -100. I thought those indicated a rich fuel condition.

[SnowTh1ef]

If you're seeing 16.4 you have a vacuum leak. Find it and fix it

[SgtMarshal]

if I blow compressed air through the evap system lines will that help isolate the vac leak?

[hensleya1]

if I blow compressed air through the evap system lines will that help isolate the vac leak?

I use a can of carb cleaner. If the engine revs up randomly when you spray, you've found your vac leak.

[Impala131]

Possibly a vacuum leak, like stated above.

Keep in mind, if you have any leaks in your headers, fresh air could get in before the o2 sensor, and throw off it's readings. The sensor would read extreme lean, and the PCM would dump fuel in an attempt to correct it.

Also, you could have a bad O2 sensor. This was the case for me when I installed my headers. The o2 just did not like being moved from my old exhaust to my headers, and it went absolutely nuts with readings. I was going crazy looking for vacuum/header leaks, and in the end, replacing the upstream o2 sensor fixed the problem.

[SgtMarshal]

I had one exhaust leak that I fixed, I might have another leak to fix, but I also don't have a converter so that could be skewing my O2 sensor data and contributing to a rich condition. I'm going to check for vacuum leaks again today