Hey guys, first proper post here.
I've got a '98 model Type RS, which is giving me all kinds of nightmares!
Got the car a while back, not running right. Installed a PFC and found the PO had stuffed up coolant temp and fuel temp sensor plugs. Swapped them back over, car ran great. For about 20 minutes until it cracked two apex seals
Rebuilt the motor, sold the PFC and refitted stock ECU.
Ever since reinstalling the motor, it has run INSANE rich. Not bothered checking with a wideband, as it pumps out clouds of black smoke at idle, and has that great overfuelling bridgeport sound. It doesn't improve as it gets warmer either, although it will idle by itself without pedal assistance (when cold it needs to be revved up, otherwise it fouls plugs). I haven't given it too much load as its a new motor, but it feels pretty flat across the rev range, apart from when (I think) the secondary turbo comes on. Cleans up a bit with ~5psi boost, but again I'm cautious of giving it too much throttle.
When I first got it, I replaced leads and coolant temp sensor as they were stuffed. Also did fuel filter. Have checked coils with a multimeter, and checked the coil loom for continuity. IAT sensor checked out within spec, fuel temp sensor was ok according to the PFC.
Scan tool showed a knock sensor fault, and MAP sensor fault. Have replaced MAP sensor with several different ones with no improvement. Have not checked the knock sensor since resetting the ECU though
I've pulled the injectors and had them tested, they were in perfect condition. Checked fuel pressure tonight, and it sits pretty well bang on 35psi at idle
I am at a bit of loss! What other things can I checked that could possibly cause this sort of overfuelling?


Brad

 

Are you certain the car has stock injectors?

Also, you'll get similiar problems if the MAP sensor isn't hooked up/vacuum line disconnected/check valve in the vacuum line (should be a filter, not a check valve).

Dale

 

i've gotten mine to do this, in a few ways.

the knock sensor does do something to the idle, so you do need to fix that.

the MAP sensor will do it, if its not electrically hooked up, or hooked up to the right nipple on the manifold. you may wanna look at the hose too.

fuel temp sensor seems to do something if its not plugged in, although you'd get a code.

the Air Control Valve vacuum lines hooked up wrong will do it. the switching valve should see vacuum with the solenoid off, and the relief should not. i had mine hooked up wrong.

 

Thanks for the replies guys. I forgot to mention last night, aside from an HKS catback it's totally stock. Definitely factory injectors.
MAP sensor is plugged in, and has the filter in line...the hose leads to the throttle body, just by the coolant pipe from memory?
Fuel temp sensor is also definitely plugged in...will investigate the ACV hoses though
Will swap out the knock sensor and see if that makes a difference!