87 gl turbo, mpfi.... usually the idiot light flickers at idle, it stays on maybe 3 - 4 seconds and will flicker... it doesnt usually come on above 3k rpms... i got a code in u-check and i think it was 22, which would mean the knock sensor, but im not 100% sure, because the light wont stay on long enough most of the time... when it comes on, the idle jumps about 200-300 rpms... when it comes on higher in the revs, the car seems like its losing power.... any help would be greatly appriciated.... i need to figure out how to do the d-check....

 

thanks

Grossgary has suggested removing the knock sensor and wrapping a few good layers of pipe tape around the threads. This will help reduce an over sensitive knock sensor.

thanks.... ill give it a try on sunday... i just hope it isnt hurting it... this is the 3rd engine in it

What caused the other failures? Any upgrades, upped boost, and what fuel grade are you running?

no upgrades.... and because money is tight right now, im running 87 w/ lucas fuel additive in it... i'll use some 93 next fill up and hopefully that helps too

D check is done by connecting the green, single pole connectors under the dash. Then turn the key to on, press gas fully, then release to half and hold there for a moment. During this time the CEL will be flashing, and you should hear the fuel pump cycling with the flashing.

 

Now start the car. Rev it over 2000 for 40 seconds. The light should go off upon starting, but then come on and blink if everything is OK. If there is a code the CEL will come on solid. If so, then look at the LED on the CPU and read the codes. D- check will only show current problems, so if you have an intremittent issue, or something that only happens while driving it may not come up at idle in D check

 

You may find that *read* mode will help you more in this case . It tells you what codes have been tripped in the past. It is accessed by connecting the Black connectors under the dash. Turn the key to on, and look at the LED. it will show you codes that were set in the past.

 

To clear the codes, plug in both connectors(green and black) and do the same full throttle/half throttle/start/run 40secs over 2000. This will clear codes and give you a fresh slate.