Troubleshooting a SRT-4, need thoughts..., Engine lean, O2 sensors showing rich...??? Options

[Delta_Phoenix]

Been trying to diagnose a problem on a friend's 2003 Dodge Neon SRT-4. I'll keep this short since we haven't been able to figure much out on this. Basically, the spark plugs are dry and white along with a very erratic idle. It will rev up and down at idle, struggling to run. It will eventually die if left running long enough. With testers and dataloggers, the O2 sensors read between 12.5 and 14.7 AFR. The car has an aftermarket Zeitronix wideband O2 sensor that also reads the same thing as the factory sensor. Even though the sensors are reading rich, there is no smell of gas from the exhaust and like I mentioned, the spark plugs are indicating a lean combustion chamber. O2 voltages are consistent with specs. A local mechanic/tuner/genius couldn't figure this out.

So the basic question I'm asking is: How do you have a lean condition in the engine, but a rich condition in the exhaust?

[Nartanian]

Yea man, I think it's a leak possibly. I would check for any loose fittings on the intercooler piping such as loose couplers or something. Also check what your vacuum pressure at idle if you have a boost gauge.

This post has been edited by Nartanian: Apr 6, 2010 - 1:09 PM