i dont know whats goin on with this car, but i'm hoping someone has experienced the same before and has a fix..

its a '99 a4 i'm working on, 1.8T, 5spd, AWD, quattro.

it first came to me with complaint of it would stall / wouldnt run / and would die while driving n not restart. i cleaned the intake and throttle body / valve body, replaced the MAF (i think because bossman or the owner wanted it changed, i dont know why it was changed.. was just handed the part lol) and it seemed to get better after cleaning those things and takin it out for a hard spin to blow crap outta it. it did good for a while, the owner saying it only died once but restarted.

then i saw the vehicle returning to me on a towtruck and i knew it wasnt good lol. someone else was sent to work on it this morning ( which i REALLY wish hadnt happened, because as i knew i would i've ended up back working on this A4) and they had got a throttle position malfunction or inop code. they didnt know what they were doing so who knows what all they may have unplugged and replugged or forgot to plug back in, or even what all they may have done.

but anywho.. here's my situation now: key on engine off, the check engine light dont come on steady and stay on. it sometimes flashes erratically, stays off, or stays on for a short time before flashing erratically again, or going off again.

the fuel pump relay also sometimes erratically clicks on and off for no apparent reason.

the car will not start.

the scan tool (that i have personally pulled and cleared codes from the car with before) only communicated with the PCM/ECU maybe twice today. other than that (the many times i tried while trying to diagnose the problem), it couldnt communicate with the ecu.


some questions i have about the car / w/e (things that'll probably burn my brain all weekend lol)

what's the resistance value of the TPS supposed to be, and what terminals on the throttle valve housing's plug is the TPS? the closed throttle position switch works fine, and there's 5v going to the plug in 2 mby 3 terminals/spots (i dont remember how many had 5v going to them... likely however many is supposed to, and this test was done early in the day before i figured out the CEL and fuel pump relay was erratically flashing on-off, with no apparent pattern)

anyone know what wire(s) supply power and ground to the ECU/PCM itself?


hopefully someone has experienced this or similar before and we can find a fix for it. if you dont know for sure, please dont provide input (like TIGHTEN THE SPARK PLUGS b/c the valve cover's leaking that i've seen around here lol), but if any further info or whatever's needed, feel free to ask