1990 e30 325i vert choking - only first 15 minutes

[usualdeviant]

I removed the weatherpack from the connector on the CTS. Much smoother line now. Still goes back and forth a couple degrees but it was a vast improvement. However the problem persists! You know, the problem where the power cuts out for a second and the check engine light comes on for a second. So anyway I tested my battery like I always do and the CCA's were lower than normal. Then checked the charging voltage and it was down to 12.2V!!! I must have checked it several times in the last few months and it was always fine (13.5-14.5V). So if the voltage goes down to 12.2 WHEN I'M LOOKING AT IT, then maybe the voltage drops below acceptable when driving it, yeah? Damn thing needs an alternator. Might need more. But at least I know it needs that. Oh yeah one other thing. The battery light has been coming on for awhile now. Only it goes off and stays off when you step on the gas. So I was just thinking it was that crazy instrument cluster. So that's why I didn't catch it sooner.

[usualdeviant]

Sorry this is kinda turning out to be my never-ending story on someone else's thread, but I'm sure some of this will come in handy for someone someday. Moving right along. Removed old Autozone alternator, spun the pulley, was gritty. Glad I got rid of it. Replaced with Bosch reman. Patched the alternator cable since the insulation was coming off. Fired it up. Let it idle. 12.2V. WTF. So I revved it a little. Went above 14 right away and stayed there. Bonus: Hood cable crapped out and got a new one from the dealer. Lubed slides and latch. Drove it. Same problem. Tested battery again, this time with an older Interstate instead of the newer Mac tester I had been using. Told it what it was, an AGM with 760 CCA's. Told me it was down to 620 and I should replace it. I ordered one from the dealer and I will be putting it in if they get me the right one tomorrow. Really no clue if that's going to fix anything but I definitely don't want to burden my nice reman. alternator with a bad battery. Just looked up the Bosch battery for this car and it has 495 CCA new. I wonder if it makes a difference with stuff...

[usualdeviant]

punnzzells said DME... On the money...

"Another update: At this point, I had my suspicions about both of my DMEs. While asking sellers if and how they tested the ones they had for sale, one of them was classy enough to offer me a piece of wisdom - that the original German fuses with a wire that goes from one side to the other, on rare occasion, have a tendency to pull apart under load. I replaced all the German fuses with Chinese ones. Immediately the car ran better, did not stumble or cut out as much. But the problem was still there.

Yes, my original AND my ebay DMEs were both bad. The original made the engine stumble and cut out at low RPM and the ebay one was after 5k RPM. I got another ebay DME, also rebuilt by Programa, and the problem was solved. What caused them to go bad? Old age? ICVs with high resistance? (I can't remember how far out of spec. my old ICV was, but I did replace it in 2017 maybe, with a cheapo Chinese one, and its specs. are pretty close to spec.) Old German fuses that pull apart under load? Something else? Some combination? Not really sure but if you find yourself having to swap DMEs you may want to check these things first. One more thing I might add is the first Programa I got had places where it said 153 AND 173. So kinda fishy there. Could be a good DME just the wrong one?

I've already put at least 100 city miles and quite a few cold starts on it since the good DME was put in, and no issues so far. The only thing keeping my hair on my head was having another car to commute with. This problem started out as a small stutter when taking off at low speed low RPM from a cold start. It started happening, I don't know, maybe 3 years ago. About 6 months ago is when it started the whole choking thing. So I have been going insane for the past half a year trying to figure this out. Hopefully this will help others in the same situation. Fixed it up just in time to pass emissions, made me feel good about the year 2018."

From https://www.r3vlimited.com/board/sho...=426328&page=2

[Mike36]

I think I know what you're talking about, I had a similar experience with a good running e30 parts car I purchased. I noticed it a few times as I was driving on the freeway. I would be driving 70 mph and all of a sudden I felt the car lose power for about a split second, It was pretty scary. It happened a few times before I stripped the car. I'm actually the DME from the parts car in mine so I don't suspect it being the cause.

[mazzo]

Any update? :)

[usualdeviant]

Mazzo, yes! There is news to report. Little sad. But. The latest (second) used / reman. DME I got exhibited a small "choke" once when driving down the road about 50-60 mph. I say it's the DME because I have 3 different ones and they each let the car choke at different times / different ways from each other. The latest one is by far the greatest. But that being the case I still suspect it's a DME issue. Tried to buy the only new one off ebay but I am having issues with the seller not sending it and saying they never got my payment. The hunt continues.