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Old 12-19-2018, 12:02 PM   #1
cmac2012
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Intermittant stalling and lurching

Brief introduction, my first post/thread here. I've seen this site from searches for years, not sure why I never joined. I was already established at Bimmerfest, got good advice there, it now seems to be dying a slow death. Have owned two E30s, both '87 325i, coincidentally made 2 days apart. My first one, bought in 2002, now has 450k miles, the second, a near cherry bought with 208k in 2013 was totaled in a freeway rear ender.

Alternate title: "car heals itself."

I hate it when they heal themselves. Aren't supposed to do that.

About 3 weeks ago I charged the battery and took it for a spin, first time in almost a year. I'm thinking, 'oh hell yes, I dig this car.' All I needed was to weld in a new CAT. So a week later I try to start it again. Nothing, just grinding that is. I put some starter fluid in the airways, still nothing. So I consult the E30 no start guide protocol, pretty sure it's no spark but I give it one quick test - disconnected a spark plug, put some #12 multi strand in the socket, hooked a jumper cable to ground, this so I could shoot for a spark while grinding it (my buddy out of town). It cranked over a few times, no spark, suddenly it not only sparked, it started up. Hooked the plug back up, it ran great. This car is still incredibly fast, even with 450K.

I welded in a CAT, passed smog, paid for tags, it ran great for a weak. Then started a lurching miss, with a check engine light flash, on the way home one night. The miss was so sudden and thorough seemed it had to be electric. Just a few times though.

The next night I was driving home and it really started missing. Then would hit 2, 3 seconds no power at all, suddenly starting back up. I pulled over, it died, wouldn't start. I missed with the spark plug wires, pushing them in at the distributor and tugged on the TPS wire back and forth. The latter as the miss was reminiscent somewhat of one on my other, now totaled E30, when the wire to the CPS strayed up to contact one of the pulleys, wearing off insulation, and grounding intermittantly (going to look at that in detail today).

Anyway, twice I got it to start back up after a full stall by messing with those items. I made it a block from home and it stalled again. This time I first tried plug wires - no start - then moved the CPS wire back and forth - no start. After about 15 minutes I pulled out a piece of wire in the trunk and tried the first accidental electro shock thing, hooked it to a spark plug socket, sure enough, after some grinding and no spark, suddenly the spark jumped and it started.

I'm going to look at a bunch of things, but who knows, I was hoping this might ring a bell with someone.

One update to all of that, my take now is that the fiddling with wires was a coincidental looking fix though the first plug gap spark might have awakened something, my best guess now is a bad coil. Search indicates that a dying coil will perform normally until it gets hot and will then cut out.

I should add that I tried swapping in a spare ECU which I tested years ago, I thought I may have hit a break but it also starting missing and then cut out after a spell. Just as well, it's nice to have a functioning spare.

Last edited by cmac2012; 12-19-2018 at 12:14 PM.
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Old 12-19-2018, 12:11 PM   #2
cmac2012
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My E30 glory days. The brontzilber the newer one, may it rest in peace.



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Old 12-19-2018, 02:55 PM   #3
cmac2012
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No, $75 later, not the coil. Seemed like a good gamble, I mean 30 years old and 450k.

This is a tough one. So far it starts up and runs when cold pretty well for about 20 - 30 minutes. Hard to imagine that something in the spark plug wires or the cap and rotor would stop performing after it warmed up.
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Old 12-22-2018, 10:36 PM   #4
locar
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Did you actually replace the CPS?
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Old 12-25-2018, 04:47 PM   #5
cmac2012
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I did a few days ago. No help. Crap. I thought I had put one years back but I discovered in my excel doc record that I put on a used one from a rig at a boneyard with 108k on the odo, this in 2013. Then again, it occurred to me, 108k on a 26 year old car? That's just over 4k a year. Prolly not realistic. And 30 year old wires can get brittle.

Dunno. Maybe I'm a huge idiot for putting money into this car. It's really weird. Recently wouldn't start for 3 or 4 days. Then I get in and it starts right up. Runs great when it runs.
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Old 01-10-2019, 12:11 AM   #6
cmac2012
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Very strange. It wouldn't start up for about 5 days straight so I left it alone for awhile, pondering my next move. A few days ago I cranked it and it fired right up. Went for a short drive, ran sweet.
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Old 01-12-2019, 11:19 AM   #7
AndrewBird
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It definitively sounds like there is a bad electrical connection somewhere. Maybe the injector harness plug? They are known for getting corroded.
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Old 01-27-2019, 12:07 PM   #8
cmac2012
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Thanks for the help. I'll look at it. What I don't know about ... if there is a problem with fuel delivery does the ECU shut down spark? Every time this won't start I had no spark.
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Old 01-27-2019, 03:57 PM   #9
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Check your C191 connector; mine had serious corrosion and when cleaning it, the wires were severely corroded and broke off.

It started with intermittent stalling during hot weather (>102) and then more frequently. I replaced every conceivable relays and electro-mechanical switches associated with fuel or ignition, including the C191 connector. Thought all was well until it stalled just before entering the Caldecott Tunel.

Now too dangerous to drive, I needed someone who knows BMWs to find the gremlin. Took car to Ryan Gangemi in Auburn and left it him to fix my e30. Ryan said it was a common proble, on e30s. He found a broken shield ground wire in the harness; replaced harness and car has been running without any issues for 3 years now.

I travel from SF to Auburn because of this knowledge and honesty.
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Old 01-27-2019, 11:17 PM   #10
cmac2012
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That's some good info. I just hit iPhone maps, dang, Auburn is a ways off. 145 miles. Not to wimp out, but two round trips, the one in the middle w/o car could be a chore. I'm finding some good info online on refurbishing harnesses. Nothing to do but get busy. Check out these links:

https://tinyurl.com/ydaxhr6o

The state of CA in its benevolence wants to give me approx $1000 for this car. Yikes. Send this little bugger to the crusher??! Nay I say! When it's running it's worth way more than a thousand.
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Old 01-27-2019, 11:58 PM   #11
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‘87 cars won’t have a C191.

Throw away the main and fuel pump relays and replace with new. Have a look at any and all battery junction points, as well as grounding points.
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Old 01-28-2019, 09:43 AM   #12
cmac2012
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I did all of that except fuel pump relay. Worth doing. I also found the a chart showing the ground pins on the ECU harness and they all check out.
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Old 02-22-2019, 05:35 AM   #13
Gee13
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Any update here?
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Old 05-11-2019, 01:24 PM   #14
cmac2012
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Oh hey, thanks for asking. Still sitting. I get depressed and apathetic and let it sit. Still have 5 months on the registration.

Last night I had to go down to the San Mateo Home Depot, don't usually go to that one and as I come to a stop light, there was an E30 coupe in front of me looking good. It took off and sounded good. I managed to stay close enough in my Mercedes diesel to follow him into a parking lot, just wanted a good look, and he pulled up alongside 5 or 6 other E30s. Turns out it was a meetup orgainzied through this site. I talked to some of the guys, they gave me some advice. Got me inspired again.

One guy mentioned the sensor in the pic here:



The green one, the lower one, but it strikes me they're both connected to water temp, and the gremlin appears when it gets warmed up. I sorta doubt they are the problem but I should look at everything. Anyone know what they are called? I couldn't find them in a brief search of my Bentley manual.

Another tip was to connect the two green wires coming from the onboard computer to the little brain under the dash. I had a problem with a bad OC about 6 years ago. No start, I suddenly noticed it read 'code' on the OC, researched it and as I had never entered a code, thought perhaps it was bad - replaced it and it started right up. I've swapped in two spares in this drama without change, but who knows, the problem might be at the box.

I haven't delved into the harness yet. I got to guard against getting intimidated - pulling out the harness seems pretty big. I struggle with thinking I should let the poor baby go the way of all flesh - ashes to ashes, dust to dust. But it still looks pretty good, never a collision, a few dings, and when it runs, it runs so good.
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Old 05-11-2019, 03:36 PM   #15
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Might be worth your time just to get a different harness. If the same issue persist you can at least take the question of wiring out of the mix.


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