You are most likely thermally shocking the sensor - leaving it on for long periods with the engine off, so when you start the engine water vapor that has condensed in the exhaust as well as the vapor that is a byproduct of the combustion reaction comes along and hits the sensor's heater circuit. The heater is ceramic. The mental image I am trying to paint is chucking a hot ceramic frying pan into some dishwater. Yours usually rattle when removed, yes?

My widebands typically become lazy, or if exposed to racegas they won't read past 11.5-12:1 AFR no matter how much fuel is thrown at them. I have had the full-rich syndrome, but it's a lot rarer.


Correct, you can.



Single cylinder roughness, eh?

Check to make sure IACV/purge solenoid/IAT plugs aren't mixed up. I think you have an 88-91 chassis ? so the purge is located on the firewall harness and not a problem, but you might have a spare DPI plug or the like that got tossed into the mix.

Check the IAT to make sure the tip isn't melted.

Check the ECU board and make sure there are no burned components.

 

the car was running good, then like flicking a switch it went to barely running and tons of black smoke out of the exhaust, while running. we didint change anything. if i leaned insanely, it would finally lean out, but then die. i couldnt get it in a place where it would run without a ---- ton of smoke and a bunch of skinny pedal.

the issue here has nothing to do with what the wideband says. the car wouldnt run. any issues with the wideband are useless at this point

John, did you say you put a stock P06 in there? like no chip? if so that will cause it to run exactly the same with those big injectors. try to scrounge up some 240's and put in there. i bet it will run smooth

 

So it wents from running correctly, then *click* rich, then *click* fine?

Sounds like bad injector(s). The overbored eBay Keihins are great for that.

 

it was running good then "click" running like ---- and never got good again. If it sits for a few min. it will start like normal, but after second or two it will run like *** again. He had DSM 450's. I usually hear of those sticking closed, not open.

I could make it idle by setting the iacv all the way open with Crome. It was at like 1500 rpm and a bunch of black smoke, but it ran.

 

had similar problem when I had an exposed v-tech wire touching the cover to the ecu.