When I had my car Dynoed and the Hondata ECU tuned, we went for mixture readings on the wideband sensor at around 13s. When I took my turbo off to send it back to get the oil leak fixed, I noticed there is alot of carbon residue in the exhaust runners of the manifold. The car has only been driven about 550 miles with the turbo on. The plugs look only slightly rich and they were changed about 300miles ago.

Is there harm in running slightly rich? Will the carbon just keep building up? Will it be building up in the engine as well? Where do all you guys run your mixture at?

 

running rich is okay...won't hurt much...however running lean is bad....you should be okay

 

Running rich is better than running lean of course, but you don't necessarily want to run overly rich either. Clogs the engine with carbon buildup and robs you of power as well. Not nearly as detremental as running lean but none the less, you want a good even mixture.

 

yeah a little rich isn't a bitch, and the occasional flame out of the exhaust never hurt anyone.

 

running rich washes your cylinder bores makes the rings contact surface of wall with no lubricant. it also fouls your plugs and causes exhaust backfires and could explode in your cat. ill tell you that 13's arent very rich at all, you must run a low boost in which case you may want to back off the fuel. Ie 8psi will not detonate running low 13:1 ratio on a low comp car, manage your A/F with an EGT, to see at what point the car needs more fuel, I manage my fueling as a relation to MAP, then I go back back and take excess out to keep my EGT's at an acceptable level.

 

What do you mean by this? BTW good call on the excess fuel washing the cylinder bore. All that excess fuel will easily disolve the finite layer of oil on the walls as the ring goes down, leaving the walls exposed to ring contact.. ewww!!