Contour Enthusiasts Group Archives Forums General Troubleshooting Diagnose by nose?

I know there probably are too many possibilities to be sure, but I thought I'd ask just in case.

Symptoms:
1) CEL
2) Funky egg smell to exhaust, bad with 87 oct fuel, much better (less smell) with 93 oct fuel.

(I have the OBDII tool, but I don't have a laptop, so I have not had a chance to check the codes yet.)
BTW- anyone got a laptop they want to trade for some stereo equipment? I do installs as a side business, so I have a lot of cool gear laying around.

History:
CEL and smell started intermittantly and progressed to constant about 6-7 months ago. Had dealer pull codes and got both banks lean, and MAF failed. They wanted $120ish for a new MAF, but I found a 75mm Proflow and KKM filter on eBay for $60 So I put those on. The MAF is calibrated for the SE engine, but I think I recall the guy saying it was set up for the stock airbox, not the KKM open element. Not sure on that. Does it matter?

Still have the stock plugs & wires, but no obvious problems with them either, runs smooth, starts easy, etc.
(Yes, I'm calling Bill today to order the FMS wires and ? plugs.)

Anyone have any thoughts?
Thanks,
Dave

The lean codes from both banks are coming from the O2 sensors. These sensors weaken over time and report a lean condition to the computer. The PCM tries to compensate by richening up the mixture. Result: Gas mileage drops and sometimes unburnt fuel makes it to the cats causing a sulfer or rotten egg smell. I think 60K is about typical mileage life for O2 sensors. The uppers seems to go sooner/more often than the lower ones.

Thanks for the help. That sounds like what is happening. I do have almost 71k miles on it.
And my milage does stink too. 17-18 tops, although that is all neighborhood stop and go, with a lot of idleing. (Pizza delivery.)

Is there not a direct code that says the O2 sensor is bad? Or does that only happen when it is completely dead, and in my case is is not dead, just weak?

Gotta getta laptop, and pull the exact codes that are in right now. And most likely a few O2 sensors as well.

Dave

New update:
I switched back to the 87 oct gas for the last 2 tanks, (prices going up again ) and now under hard acceleration at mid-upper rpm's (above 3500) I'm hearing a light mettalic rattle from the engine. Pinging? I never was sure what that sounded like. Yes, I immediatly got off the gas each time it made that sound.

Does this confirm the above diagnosis, or add a new wrinkle?

Thanks again,
Dave