Harowing

OHK so, i bought another one (maybe i am legally insane?) this ones a 1991 model 80 quattro 2.3l ng(just like my old one) and...heh...yeah its got issues(begins beating head on wall) cel NEVER comes on. no the bulb isnt burned out, i replaced it with known good bulbs. twice, just to make sure.
wont throw codes, doesnt come on soon as key is turned to on, nothing.
now if i understand correctly, no matter what is busted in the system, the cel SHOULD come on, even if its the ecu thats busted. so, my main suspect is wiring, now the problem is, i have not acquired a new haynes/bentley for the new one yet(old haynes does not cover the 91, or ANY quattro models) so im a little stuck, i suspect the thing isnt getting power to the ecu/self check/god knows what else.
now, on the old 88 there was a wire that popped out of the firewall and ran up the coil, to the positive side, i believe this was the power source for ecu? maybe im wrong dont know, however, its missing in the new 91, im not sure if the 91 requires that wire or not? or even if i am on the right track at this point, so any info ya can give me would be nice(this is for emissions purposes, right now, its failing....horribly, and, i did just for giggles swap the ecu off the 88 model 90 to the 91 model 80 just to make sure it wasnt the ecu. no change)

thewraith420

damn dude wish i could help ya

fjasper

Is it running ok? Does it have a fuse in the "spare fuse" socket?

Harowing

Yeah ran alright, not perfect but ive seen worse, the ecu was shot replaced that, passed emissions with flying colors, now I've just gotta fix the drivability problems (dfpr running at 0ma constantly, not a mixture issue far as I can tell but all sensors seem to be functioning properly) (shrug)

fjasper

If the DFPR is constantly at 0ma, I'm guessing either the output isn't working, wiring is broken, or it has an open circuit inside the regulator. Maybe check its resistance, there's a spec in the book, if you need it I can look it up. I want to say something like 1 ohm.

Harowing

Would appreciate it, though I've tried 2 diff dfpr's with same result, planning to replace the wires to it tomorrow

fjasper

Resistance value for the dfpr is listed as "approximately 17.5-21.5 ohms." Yep, the book says "approximately." Page 25-220-1.

On page 25-230-2 it says the fuel injection control unit will generate a fixed current of 100 mA to the dpr when the ignition is on and the engine is stationary.

Harowing

Awesome thanks for the info buddy

Harowing

Ok 18.5 ohms of resistance at dfpr, and 0.06ma with key in on position

Harowing

Ok just tested for MA at the ecu harness itself pulling a nice round...0.00 ... Ideas? Bad ecu, again? even though everything else seems to be functional? And it passed emissions?