Re: What causes Cylinder Head carbon deposits

Your carbon problem may be directly related to the 180 deg stat. Don't forget the 180 deg is the temp at which the stat is fully open - it will begin to open 10-15 deg lower temp meaning your engine may actually be running in the high

160's much of the time. The PCM uses the ECT info as part of it's fuel/air mixture calibration. The PCM starts out with the fuel curve enriched when the engine is started cold and leans the mix as the engine warms. If it never "sees" a warm engine, it may run rich resulting in carbon during normal driving which you describe. The fact that you hear or have no ping on 87 octane fuel is likely because of this enrichment required by the reduced engine operating temperature. Since the aluminum heads have a reduced propensity to detonate anyways, I would suggest going to the OEM temp stat. You should be able to see the fuel curve if you have a way of minitoring the input/output of the ECM.

You may want the tuner to lean the fuel curve a bit to reduce carbon buildup or, maybe try compensating with timing settings to get a bit better fuel combustion. Again, I would try the OEM temp stat before changing the settings unless you are into fulltime performance. If it is a weekend warrior, you may want to just use the stock setup and, re-program or swap chips for weekend duty.

Steve,

what "related hardware" are you refering to? The intake manifold was also changed. My 0-60 times have dropped by .5 to .75 of a second, so I clearly have more hp now. The cam from the vette would not work in my car. (IMPALA SS) it would have caused a drop in torque, i need every ft/lb to get that big beast rolling. A more agressive cam would have most likely resulted in a FAILED emmissions test here in Pennyslvania, so I kept the stock cam.

I'm not looking to make the car any faster right now, just looking on some ideas as to where the carbon build up was coming.

Thanks

Faster 0-60 means you have a bit more torque NOT HP. Torque = Acceleration, HP = Top Speed. That is because the aluminum heads allow the computer to increase timing advance due to the heads running cooler and lowering the possibility of Pre-ignition (ping) The carbon is being caused by the heads transferring the heat away faster combined with the cam you are using.

Related hardware = Computer or chip for that engine, Cam, Intake, different pistons. Those are all different.