how much carbon do you have depositing on the end of your exhaust tips? i washed my car a week ago and looking at it today the lower part was completely black.. maybe the car is running too rich?

 

I have to wash mine weekly. The bottom of the tips is always black from the condensation being blown out of the exhaust washing down the carbon.

 

yeah they fixed everything. i'm even getting a new rear diff.

 

Are you running test pipes?

 

too rich

 

nope. no engine modifications. i did have a plenum on there, i was thinking that maybe the ecu had adjusted itself to have the extra air and when i took it off caused it to run rich, but i think over the 15k i have logged since then, the ecu would have figured it out.

 

While it makes sense that the carbon would be caused by the engine running too rich, it's not that simple. I took my Z in after I first noticed it. Basically I was told it was normal and there was nothing they could do about it. Unless it throws a CEL, it's not considered a problem. Apparently, the ECU has to decide there's a problem before it will be touched under warranty. As long as it's operating within acceptable parameters it's considered "normal".

I thought that the addition of a plenum spacer would have helped lean it out a little I haven't seen any noticable reduction in the carbon buildup.