Engine runs too RICH

[wizard007]

Basically my 1990 Si is running too rich. The exhaust pipe is very black and the plugs are moderately so carboned up. It is a 1.5L MPFI with stock intake, running about 40psi, new fuel filter, intake was just cleaned with TB cleaner. It is not putting out any codes. It still gets great MPG ... etc. I don't know what else to check. The ECU is a chipped Integra unit. Someone did mention that I should stick with an Si or PG6 ECU mine is a PM7. Could that make it run rich? O2 sensor is brand new..

[los02]

I'm having the same issue... running rich. But I actually notice a 60 mile drop in mileage per tank. I think my issue may be the oxygen sensor. But I don't see the CEL anymore.

[wizard007]

I can try to switch out the ECU to see if that makes any diff. I know the current ECU has more aggressive tuning and it might include holding the injectors open a bit longer.

[Sirfallsalot243]

1.5L engine with fuel maps for a 1.8L...

What do you expect?

[liljoker]

you got a chipped ECU which basically is giving you more fuel. Which is probably a lot for your 1.5L.

[lowcivic66]

Originally Posted by Sirfallsalot243

1.5L engine with fuel maps for a 1.8L...

What do you expect?

+1 thats the obvious explination.