My car is an 89 LB9. I get black soot on my bumper above the tailpipe a day or two after I wash the bumper. The car is goes into the proper mode after it warms up. I run a stock 195 thermostat with the stock prom as well.

I also dont know if this is related, but sometimes my car smokes wildly at startup, and sometimes not at all. For example: Today after sitting for only 2 hours, the car smoked quite a bit. However, later today it did not smoke after sitting longer.

Could I have a leaky injector, that leaks fuel onto the top of a piston when the engine is not running, and dumps too much into the cylinder while the engine is runnning?

Help me out here. I have access to Diacom software, what should I look for? What will indicate a rich condition?

Thank you

 

Is the smoke black or blue? (fuel or oil)

 

The smoke is blue/gray color. The soot is black. Thanks