The black stuff on the exhaust tip is not from gasoline detergent additives. It is excessive carbon, and a build-up of it on a *low mileage* newer car is usually a sign of the air/fuel mixture being too rich.

Your dealer is a parts changer / code reader, and they're not going to put in the time to investigate the cause.

 

Ok, HOW do they investigate the cause? No trouble codes. Tech II plugged in as he drove the car around showed injector pulse and fuel trim as being ok. I cant just keep bringing the car to the same place. Suggestions? I totally think it is running rich like you guys do. That would explain away the mileage.
The shop foreman showed me several corvettes with the same stuff in the tailpipe

 

I'd have it re flashed..you might not get a code if the puter 'thinks' its doing everything right..its possible your car was loaded with the wrong program..
weak plugs won't probably show up either..hows the power?

 

My car's had a sooted-up tailpipe since about a month after I bought it, but it still gets great mileage. 11 miles of driving everyday is barely enough to get the engine warmed up and the computer out of warm-up mode. Try another dealership and see if they can find anything. As the adage goes "You can keep *****ing on internet forums but you're car won't get fixed any faster."

 

They checked for updates. It has the latest and greatest. They wont just reload it. I have to take it somewhere else. I will start making calls soon to other dealer's service dept's and pose some questions before I make the drive and take the time off from work.

 

My car warms up to operating temperature very soon after I leave the driveway. I live in sunny california.

As for this......



"You can keep *****ing on internet forums but you're car won't get fixed any faster."

Understood. I guess it's not ok to put things out here for comments. Won't happen again.

 

My tailpipe looks the same...pretty sooty but I've been getting great mpg...but then again my commute is 99% highway and 100 miles a day minimum


I feel your pain..it stinks having something new and it not working the way you would like it to.


Hope you get it taken care of...I have some issues with mine but finding the time to have it looked at is tough..and I only have about 6000 miles to go before my 3yr/36K is up on everything beside the powertrain...so maybe a little more than a month and a 1/2 to go



Goose

 

The soot comes from the first few tens of seconds, when the engine's not up to temp, and neither is the catalyst or O2 sensor, so it runs in open loop, and a little richer (like a choke on a carbed car), but once the cat lights off, there'll be no more, so you'd need a lot of very short journeys to get a lot of soot, since all car manufacturers have fitted things like insulated manifolds,or close-coupled cats and air injection to make that light-off time as short as possible. My cars don't do a lot of miles, the Camaro has 10000 miles after five years, and there's no soot on either. I averaged 26.5mpg on the HHR through the winter, and got 33.5mpg on the last long trip with it, fully loaded.

 

Well, when you're posting stuff like "1st trip to the Idiot Dealership", what kind of response are you expecting?

To me, 18-20 MPG in short city driving isn't surprising. The car's barely warmed up and the engine is spending most of its time getting the 3500 lbs. of steel moving from a dead stop after every stoplight. Not to mention any idling that you're doing too. You can have them reflash the PCM and throw all the K&N crap you want at the car, but the mileage isn't going to get any better.

 

I had an issue with an '96 Olds -- electrical. Dealership could not explain it, but fortunately they didn't give up. After months of dealing with and not getting it fixed, I called Olds. They got involved, and after several more dealership visits, they acknowledged the problem and that they just didn't have a resolution. Unfortunately, it went well beyond the lemon law period. Olds did, however, make an offer to take it back on a trade-in on a new Alero at a heavily discounted price.

Go ahead and call. Get GM involved in what's going on. I think you should give them the benefit of the doubt that they will be interested in helping you with this issue.