[HUMMERcustoms.com/TAZ]

The GM throttle body butterfly on the fuel injection systems have had a history of random tighter than spec tolerance when the throttle body was machined and pollished down to tollerance. Just random like any other parts have same issues sometimes.

You do as mentioned already and clean it yourself. But, I would not worry unless you get the throttle feeling like it is hanging up giving you a fluctuating idle speed. You can even have such a trouble that you will let up on pedal and you will not fill it come back to normal position which of course means higher RPM and having to use more brake to stop.

I experienced it badly with my new 1999 Silverado and at first had to clean the area right where the butterfly closes to meet body wall and as carbon built up it would stick and have a higher idle. It got to where I was having to do it to much and I went in to the dealer and found out that on my model truck they had a silent recall to check and replace the throttle body itself when tolerance was checked to be off with complaint of high idle or throttle sticking.

It has not been an issue on any more GM rides I have had but, know of it happening to others. I have since going through the problem with my truck just tell them what it may be.

I have not heard of the problem on any other brands but, not around many with other brands to hear much if it is happening. I would think carbon building up would occur on any throttle body intake at some point unless it is handled by using a greater tolerance.

I should say it looks like carbon build up but, with it not in an area of combustion it really would most likely be just a fine dark dust catching right in the butterfly area. So I apologize if I have been some what misleading as it is just the look that it has is black carbon.

TAZ