Help! Intermittent dying, CEL comes on all power loss.

[driftxsequence]

Got new oem main relay. Car drove for 10-15 minutes no issue....then i started happening again. Looks like the crank sensor is the next...

[nando]

This fooled me before, too- mine would 'blink'- the relay would interrupt DME power
for just long enough to reset it, and then it'd go through the startup diagnostic,
which illuminates the CEL.

fwiw.

t

yeah, that's what I remember happening too.

But, it could very well still be the CPS. However, I'll reiterate that I'd still replace the relays anyway. They are cheap and they cause lots of headache when they fail.

With the CPS make sure you get the clips and protective cover. Lots of times people leave them out and the wire rubs on the pulleys, shorts out and causes it to fail.

[packratbimmer]

Check the resistance value on the CPS and giggle it around a bit down next to the crank (repeat several times). I bet moisture ran down the wire and fouled it.

If that is the culprit, get an OEM replacement - aftermarket can be trash and cause problems.

[driftxsequence]

Edit: you guys responded on how to check the cps.

Btw thanks for your help guys.

[driftxsequence]

Went to the junkyard got a spare CPS. Factory BMW unit. Still does it. Also tried a replacement coil, bosch unit. Still happening...

This is the ONLY lead I can seem to figure out. 2 wires on the distributor were loose and the one with that weird sensor on it was all corroded. Would this cause that issue?

The rest of them were all nice and shiny..

[dnguyen1963]

That looks so bad. Time to replace the distributor cap and rotor.

[peterman]

That looks so bad. Time to replace the distributor cap and rotor.

and plug wires

[e30onBBSs]

Does it misfire?

[driftxsequence]

cap and rotor replaced, wire was cleaned up and made no difference.

I did make some progress tonight. the issue is 100% GONE When the ICV is unplugged. When I plug it in, the car will start acting up. This is weird because the ICV is brand new. With the key on and the engine not running, it can be heard buzzing...

Not exactly sure if I'd say its a misfire. its a complete loss of power, then power comes back on and off rapidly.

[driftxsequence]

I noticed with the ICV unhooked. the ECU is quiet. With the ICV plugged in the ECU buzzes....

pulled out the multimeter and i didnt get anywhere close to the 20/20/40 ohms that i read about. it was 80,140, and like 200+. I'm gonna assume the ICV is bad :)

[Lirker]

I would say the round C191 plug isn't making proper contact. Same thing happened to my car, I checked it and it was that. Either that or the main relay, or crank position sensor like people are saying. if that fails check fuel pump. The wires on mine blew out before, and I didn't even know for a while, so check that as well.

[driftxsequence]

got a replacement ICV. car idles low, like 400-500 RPM...but it runs and doesnt shut off on me now. I'll check C191 but for now it seems to be better.

[Maddog]

I hope you found the problem. If not, do more than just check the connector for corrosion. The wires could be barely hanging on to the pins due to corrosion. I had intermittent stalls and bucking which worsened when I replaced the TPS, AFM and fuel purge valve which I thought were the problem, but only increased afterwards. I disturbed the C191 connector during the work and inspected the connector thinking the problem were corroded connections. Well during the inspection 3 wires were either corroded from the terminal or barely hanging on.

Replaced the BMW coupling and pins with Weatherpack; so far, no more surprise stalls on the highway which is pretty stressful when you are in the fast lane during the stall.

[driftxsequence]

Wanted to follow up for anyone else experiencing a similar issue. I replaced the ICV. This caused the car to buck on the highway till the CEL came on and it went to limp mode. Idle would hunt a bit as well. I tore out the c191 plug and replaced with a Deutsche connector. This did not fix the issue either. Finally, i went back and swappd my ECUs as i had a second ECU i had ORIGINALLY swapped before acquiring an ICV. All symptoms went away and the car drove beautifully.

Concensus: the high resistance on the failed ICV blew out the idle circuit on the ecu. This meant it was not correctly metering air causing a lean condition on the highway due to being open too far. When the car went to limp mode it was adding enough fuel for it to drive problem free.

Replaced parts:
Icv
Ecu

Not required replacement:
C191 plug