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..

 

if you have to pass emissions, then i would not change the chip.
any codes?
maybe IACV

 

it is not flashing any codes.. what are you saying about the chip/ECU?

 

You should stick with the stock ecu. I have one if you want to buy it.

 

pretty much what you said:
"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?"
that is not stock, right
Do you have to pass emissions ??

 

if your still making good power, and getting good economy, and dont have to pass emmsions, i would just leave it...really the only worrie i have is fouling a plug