I realize that this is a third gen site, I have found a lot of useful info for my third gen Formula. I also have a fourth gen that is currently having "issues". I'll post the question, if you want to give it a shot then by all means thank you! If not, could you direct me to a site that could be helpful?
Thanks!
-I have a 2000 LS1 T/A. The car is stock except for a flowmaster cat back which has been on the car for three years. The car has 56K miles. The service engine soon light is on. Trouble codes P0172 (System too rich, left bank on 4 sensor systems) and code P0175 (system too rich, right bank). I believe this to be an oxygen sensor, however, the car has 4. Any suggestions on how to figure out which one/ones are faulty? Any other ideas as to what may be causing these trouble codes? Oddly enough, I've been thru three catalytic converters on the car (two lefts, and one right, replaced under warranty), so the emission system has always been a little screwey with this car.
Thanks for your time!

 

Both those codes indicate that the engine is getting too much gas, and the ECM is having to significantly reduce the injector pulse width to compensate. 3 bad cats in 50k miles also points to a severely rich condition. How's your gas mileage? Pretty bad?

Check your fuel pressure. If the regulator's bad it can cause the car to run really rich. Also make sure it has a clean air filter.


Also don't be surprised when this gets locked. It's distinctly not a 3rd gen related question.

 

Might try some of the fourthgen sites, like CamaroZ28.com or LS1 tech.

But, just a thought, when the cats were replaced under warranty, were the primary O2's changed then, or did they leave them alone? I've heard of a few cases where a clogged cat ruined the O2 sensor, which in turn puts the new cat on it's deathbed before it finally sets an O2 sensor code, in what amounts to somewhat of a viscious cycle.

Also, those codes relate to the primary (i.e. front) O2 sensors, which are the ones used for closed loop fuel. The secondary (rear) sensors on OBDII are only there to verify that the catalytic converters are functioning.

A couple of leaky injectors, or a fuel pressure regulator with a leaky diaphragm, might be the source of the rich condition.

The GM factory service manual will have a diagnostic flowchart for each malfunction code. Use it. If you don't have a manual, get one. It'll pay for itself over time.

Good luck,

 

I do not believe that the O2 sensors were replaced...I'll start there. Any suggestions on where to get a service manual from?
Thanks!

 

The GM manuals are published by Helm's. http://www.helminc.com

Often you can find them used on eBay.