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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series & 4 Series > E30 (1982 - 1993)

E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 03-15-2017, 07:16 PM
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cmac2012 cmac2012 is offline
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Strange fuel problem

My older car had been having a seeming fuel pump issue, thus I was driving the newer one and got rear ended.

Trying to get it going, I had a spare inline pump and it sure seemed like that was the issue. Sure enough, it ran great upon putting it in. I was surprised it started as the battery had only charged up to 11.25 (6 years old, I didn't unhook it while it was down (doh)). The next morning it would lurch badly upon acceleration, just a seriously bad miss. I found one bit on the web of a guy claiming that a battery just about on the way to the recycle depot would sometimes result in that sort of thing - a confusion of the ECU resulting in bad driveability. I put the trickle charger on the battery in the banged up car and put it in the older one the next morning. Ran great. Hallelujah. I drove 25 miles to the only Pick n Pull in the area (San Jose N) and got a heater fan motor and got that running. Drove great both directions.

The next morning: no start whatsoever. The pump I'd put in was a spare and had been whining badly, I'm thinking maybe it was on it's last legs. Had not stored it wet which I've just learned you should do with a used pump - keep gas on the membranes so they don't dry out. Not sure how to pull that off, but that's another story.

Sorry to make this long, but it's odd. I didn't want to put a new inline pump in this old beast, the newer rig has much more life and promise, if I can get it running again w/o huge residual ill effects anyway. So I took the pump out of that one, I know it works, I can put the new one in that car later. Voila, car ran great, took it for a couple mile test drive, smooth power, amazing how vigorous that engine is at that age.

The next morning ... WTF? I'm back to the hard lurching thing. I limped it back, took my van to do a job, come back home and the car will absolutely not start. No hint of firing. I pulled the fuel return from the rail, put some funky clear tubing on it sticking into a jar and cranked. No fuel.

I looked in the fuse box. The #11 fuse for both pumps, a 15 amper was one of these below (anybody know what brand that is?), the old style. A while back I had a bad turn signal owing to one fuse of this sort having gone bad but not looking melted. I found a newer one, this one pumped fuel, and I'm thinking EUREKA!, it was an intermittant fuse all along. Except it wasn't. Holy crestfallen blues batman. Still lurching.

I've looked that the wires attached to the inline pump, no apparent issue there. Last night I also put in a new aftermarket guts for the in-tank pump, it's a Swedish brand my parts guy got, a Professional Parts SWEDEN brand I guess, that's on the box. I tested both the old and new using a very crude 'does it pump' test. I put a standard household light switch in a long wire, pinch clamped it onto the old battery I'd taken out, now charged up to 12.0, and pinch clamped another long wire to the neg post, used alligator clips to get both on the correct terminals on the pump, sat it in a old pie tin with a half-inch of gas in it, hit the switch and the old pump, a Vega part I gather originally, an O'Reillys cheapo, pumped the weakest stream of gas. I tried the new one and it gushed into a can I was holding. Just way stronger.

Long story short, any idea on what might be causing this intermittency?

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Old 03-15-2017, 08:52 PM
7pilot 7pilot is offline
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On a car that has been sitting?
I'd drain the tank, and see if there is rusty sediment on the tank floor.
I would imagine that the injectors need some attention.
switch over the fuel pressure regulator also.

m
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  #3  
Old 03-15-2017, 10:41 PM
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cmac2012 cmac2012 is offline
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That is a good point. It's been sitting a while. It's been an odd year for me. I had rotator cuff surgery August 31 last year on my right shoulder. I've healed up quite well , and that's not always the case with the full tear like I had, also had biceps long head tendon reattached and I read later that leads statistically to worse outcomes. So I have been very lucky in that regard.

I mention this because right about the time I went in for surgery is when the older car started acting up. It was virtually impossible to do any work on it and I had the newer car working well, I shifted with my left hand while steering with my knee. I got pretty good at it, I would stay in gear until I got to a good spot to do it.

Anyway, it's been sitting about six months. When I installed the in-tank pump, I looked down through the hole in the tank, and OMG it's squeaky clean down there. I don't understand why, but it is. And the filter on the shoe is absolutely clean, just pristine. That part new as of about 10 years ago.

My best guess now is the problem in one of the lines. I finally broke down and got a pressure tester, I'll try to do that between now and midnight. O'Reilly's will loan you a pressure tester for 48 hours. You pay full price, and if you bring it back in time you get a full refund.

I installed refurbished injectors a couple of years ago, gave me a nice powerbuzz. You're probably right, wouldn't hurt to look at them.
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Old 03-16-2017, 12:56 AM
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cmac2012 cmac2012 is offline
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Oh man, this is heart breaking. Perhaps the way rigs go to the boneyard. I also got a new can of electronic clearer at O'Reilly's, sprayed the receptacles for the relay and buffed up the prongs. Started right up, I went for a test drive, no lurching, no sudden dying as it had been doing. Went on longer and longer spins and never a complaint. Stretched it out up to 4K a few times, ran like a champ.

I'm thinking, can't be, dirty contacts and that's it? But I'd have taken it. Unfortunately, just before bed, I tried it again. Ran for 10 seconds and died, after it used up the remaining pressure in the line I'm guessing. Will not crank. I don't really need to check further, it's not pumping fuel.

I swapped in a spare ECU that I tested about a year ago when I got it. No change. I might need to chase down every circuit that leads to it for continuity, etc. Bentley's has the procedure.

But I don't think it's injectors or pressure regulator. It runs too good on those brief forays. Something is stopping power to the injector circuit. Almost certain.
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Old 03-16-2017, 07:37 AM
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hornhospital hornhospital is offline
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Sounds like a dying crank position sensor to me...... Mine did the same thing for a month, then finally wouldn't start at all. A new CPS cured it.
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Old 03-16-2017, 08:22 AM
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cmac2012 cmac2012 is offline
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That sounds like an excellent tip. You might recall the issue on my other rig, sporadic missing, that ended up being shorting of a wire to the CPS owing to worn insulation and bare wire contacting a pulley/ground.

I looked at that wire bundle on this car and it looks good. But the symptoms are not dissimilar. I'll do the test on it. I'm hoping the sporadic thing doesn't yield a clean bill of health when it's not the case. Could be a simple part replacement is in order.
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Old 03-16-2017, 12:27 PM
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cmac2012 cmac2012 is offline
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The CPS was covered in grease and gunk. I cleaned it with WD40 and then electronic cleaner. Maybe a small improvement, but that's it.

Oddly enough, neither Bentley nor Haynes says anything about the CPS. Maybe I'm missing it, but I looked fairly closely. I could've sworn I found the terminal and checked resistance a few years back, but I can't find a description of where that is at the moment. It's on the left side of the engine somewhere. Anybody know a good link for that?
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Old 03-16-2017, 02:24 PM
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See the Ignition section. Here's the location:

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  #9  
Old 03-19-2017, 03:06 AM
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cmac2012 cmac2012 is offline
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Ah, of course: the pulse sensor. I thought I remembered that they don't refer to it as a CPS.

I tested fuel pressure, was steady and consistent when the relay was jumped. Then I put the relay back in and started up and the pressure was not consistent, jumping around a bit, and when it died, the needle took a dive right at the moment it stopped. I was under the impression that pump would keep running for a couple of seconds after the engine stops.

This is getting hard. I put the new CPS in, it ran good for about 100 yards then started lurching again. I probably should've done the resistance test, but there was a worn spot on the insulation, the wire was very brittle, I thought perhaps the wire was shorting, but in that condition it might not continue long anyway.

I checked all the ground connections, they look pretty good. No corrosion no looseness, the nuts are dirty. I was examining the ground connection just above the fuel pump under the rear seat and noticed where one green with lavender wire was attached to two others, same color, with a crimped brass sleeve. What caught my eye was the green wad of corrosion around it. I did a search: fuel pump circuit. I thought I'd found it - the single wire was barely holding on. I cleaned it up and soldered in a splice - wasn't it.

What's weird about this the way it will stop running and then heal itself after 10 or 20 minutes, will start again and then lurch and die. And then won't start for a while. I did a search for symptoms of a failing coil and found this:

The signs of a failing ignition coil include backfiring, starting issues, lowering gas efficiency, engine misfiring, vehicle stalling and worn out spark plugs. The most common symptom of a faulty ignition coil is when the car runs for a while and the engine dies abruptly.

Sounded promising. I swapped in the coil from my wrecked rig. Ran good for longer this time then started lurching. It's torturing me.
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Old 03-19-2017, 04:04 PM
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hornhospital hornhospital is offline
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Do you have a spare, known good AFM? Try that.
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Old 03-20-2017, 06:24 AM
7pilot 7pilot is offline
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While it is in lurching mode, how does the tach needle behave?
Does it drop like they ignition has been turned off via the key? and does it simply pop back up to rev speed?
Or does it slam to zero,and slam back up? very violently.
The latter would point to the ignition system.
I see that the battery is getting old...maybe it is not accepting a full charge. I'd have it load tested.
I'd also recommend switching the alternator out with the one from the wrecked car, if it sustained no damage. would like to rule out a charging system fault.

m
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Old 03-20-2017, 01:07 PM
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cmac2012 cmac2012 is offline
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Quote:
Originally Posted by 7pilot View Post
While it is in lurching mode, how does the tach needle behave?
Does it drop like they ignition has been turned off via the key? and does it simply pop back up to rev speed?
Or does it slam to zero,and slam back up? very violently.
The latter would point to the ignition system.
I see that the battery is getting old...maybe it is not accepting a full charge. I'd have it load tested.
I'd also recommend switching the alternator out with the one from the wrecked car, if it sustained no damage. would like to rule out a charging system fault.

m
Good questions. I'll take it for a drive soon. The power cut out is so sudden and complete, it does feel like complete loss of combustion and right now. Not sure a dying pump would cause that complete of a loss of power, instantaneously anyway.

I put the battery from the wrecked car into it. It's 4 years old so it's not ruled out. I'll check that again.
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Old 03-20-2017, 01:17 PM
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cmac2012 cmac2012 is offline
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Do you have a spare, known good AFM? Try that.
Good idea. I was thinking that I have completely ignored that section of the engine. I can put the AFM from the wrecked car into it easily enough.

I'm leaning more and more to not trying to revive that car. My parts guy advises against it, and he's no shrinking violet when it comes to rebuilding old cars. He has an early 50s Chevy and an early 60s XKE that he's been working at for years.

The drivetrain clearly got shifted in the accident. Was nearly impossible to get into reverse, the shifter kept hitting the left edge of the console opening.

If I decide to drop the engine from it into my older car I can certainly replace the parts.

The CHP still hasn't finished the accident report, 16 days later.
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Old 03-21-2017, 01:47 AM
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cmac2012 cmac2012 is offline
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Bentley says they have no resistance test or otherwise to test the AF sensor. I swapped in the unit from the wrecked car and no, that wasn't it. Didn't start right away but did a minute later and I drove for maybe 200 yards before the lurching started in. It was worth a try, didn't cost me anything.
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Old 03-21-2017, 02:00 AM
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cmac2012 cmac2012 is offline
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Quote:
Originally Posted by 7pilot View Post
While it is in lurching mode, how does the tach needle behave?
Does it drop like they ignition has been turned off via the key? and does it simply pop back up to rev speed?
Or does it slam to zero,and slam back up? very violently.
The latter would point to the ignition system.
I see that the battery is getting old...maybe it is not accepting a full charge. I'd have it load tested.
I'd also recommend switching the alternator out with the one from the wrecked car, if it sustained no damage. would like to rule out a charging system fault.
It is weird the way this car heals itself overnight. First thing today I drove back and forth for maybe a quarter mile, it behaving perfectly, accelerating hard then it died while I was doing a U-turn. Started up but set in lurching.

Tonight after swapping the MAF units it died hard after a couple hundred yards. The tach needle did just as you describe, drop immediately to or towards zero and would spring back up if the engine caught.

I agree it does seem electrical in nature. I was thinking to check all the wires to and from the ECU - doing it according to Bentley instructions. It can't be a fully severed wire as it wouldn't run well for brief spurts as it does now.

It's as if some electrical component overheats in a hurry and gets enough rest to revert to proper temp, allowing it to start. Somebody somewhere must have experienced this. I'll keep looking.

That battery tested at 12.5; I took it from the wrecked car. When started the voltage went up to mid 13 range.

Something odd just occurred to me. When I first got it running, I did a 50 mile round trip to a boneyard with no incident. I got heater fan blower motor. I had already tried a new'used resistor that provides multi speeds, that didn't do it. I put the motor in the night before the lurching thing started. Anybody know what this is?





I had to move it to take off the firewall piece to get the fan it. It works. Oh boy. I hate a foggy windshied.

It seems to be a wire junction of sorts. I pushed it around a bit. Seems a long shot but it didn't show the lurching routine til the next morning.

Last edited by cmac2012; 03-21-2017 at 02:48 AM.
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Old 03-21-2017, 06:13 AM
7pilot 7pilot is offline
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Have you disconnected the plug on behind the bitch pipe and used some de-oxidizer to freshen up the connection?
it is the sub harness that supplies the injectors, the coolant temp sensor, etc.
Clean up the engine ground connection by the oil pan as well.
Whatever the problem is, the electrics are adversely affected by under hood heat.
Check the primary and secondary resistance of your replacement coil also.
m
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Old 03-21-2017, 01:30 PM
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cmac2012 cmac2012 is offline
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Good ideas all. I don't have de-oxidizer on hand but I used the CRC electronic spray cleaner followed with some dielectric grease, after a good drying time of course. I also did the MAF and coolant temp sensor connections. Started right up, dang it sounded good, went the usual 200 yards before lurching. I made it back home, let it idle, went about 10 minutes before dying. I started it back up, if I would lightly touch the pedal, it would begin to die. I took it up to about 2500 and it died completely.

I may breakdown and try the continuity test on every pin involved in the ECU. Maybe there's one wire with a compromised connection. Maybe I'm desperate, not sure.

My neighbor at my warehouse shop, a welder and really good mechanic, although not much Euro experience, has been patiently listening, he insisted I try the fuel pressure test again, which I did, got a better tester at Autozone on the borrow routine, checks out fine. He now agrees it's electric, after the cleaning today, thinks I should take a look at the cap and rotor. I just looked at my records, pretty sure I've not replaced it. I hate to admit it, I got a bit slack in my record keeping in the last few years. I know I put a new C&R on my van, and I may have put one on the newer car, now dearly departed. I could just swap them, it's a bit of work, IIRC you need to remove the radiator to do so. Oh well, I could just go the route my welder neighbor keeps advising:

'Get you a new radiator cap, hang it from the ceiling of your garage by a wire, and back you a new car in under it.'

Last edited by cmac2012; 03-21-2017 at 01:37 PM.
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Old 03-21-2017, 04:33 PM
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cmac2012 cmac2012 is offline
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The more I think about it, cap and rotor is unlikely to be it. It wouldn't run as well as it does for my daily five minutes of excellent performance with a bad C&R. Yesterday morning, I must've gone nearly a half mile back-and-forth on the street out front before it started acting up. I was going over 4000 RPM now and then, excellent power, no hesitation.

It occurs to me that I did not clean the connector for the CPS. I'll do that tonight and see what's up.
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Old 03-21-2017, 06:59 PM
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I had that happen when the governor and rev limiter decided to kick in at the same time. ended up being a loose ground connection. couldn't get over 55mph and shook like hell.
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Old 03-22-2017, 12:43 AM
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cmac2012 cmac2012 is offline
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Pretty sure I looked at all of them. Better go over it again. If they're tight and no sign of corrosion, I'm guessing it's overkill to loosen them and clean everything. I might do it anyway.

One thing that gives me pause, I discovered a factory splice - one green w/lavendar into two of same color, crimped in a brass sleeve that had morphed into a ball of green copper/brass corrosion. I cleaned it and spliced around it. Point being, if there's that one, what others might there be only better hidden?
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Old 03-22-2017, 06:15 AM
7pilot 7pilot is offline
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Is the car still equipped with Cat converters?
I once encountered a car that would only run for roughly 15 minutes.
The cat con matrix had melted into a roughly ball shaped mass in the converter. It would roll back to the cat outlet and obstruct the flow of exhaust.
No air out = No air in.
After it rolled away from the outlet the car would run.
Had a similar problem with a Porsche 914. turned out that it had a surge pot in the gas tank that had a mass of rusty coffee grounds contaminant that would migrate to the slits in the pot and block the flow of fuel.

m
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Old 03-22-2017, 08:33 AM
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I'm guessing it's overkill to loosen them and clean everything. I might do it anyway.
Absolutely, take the ground connections off and clean them. It's not overkill. They can look fine but be seriously corroded under the fastener/joint.
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Old 03-22-2017, 10:46 AM
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cmac2012 cmac2012 is offline
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I'll do it. Not sure what to make of dielectric grease. I gather it has some insulating properties. I guess it wouldn't actually interfere with the electrical transmission in question but it is curious. Ah, just searched the question a bit, this fellow put some energy into researching the point:

https://www.w8ji.com/dielectric_grea...ive_grease.htm

Cliff notes version: dielectric grease will yield better results.

Another angle I'm thinking to pursue is to start it and immediately shut it off one morning and then do all the Motronic electrical tests as outlined in Bentley. Then I'll get it good and warm such that it won't start - it will usually go into a mode of not starting that lasts for a half hour or more. And then repeat the tests. Who knows, I might find a pin that behaves differently. Not sure how I'll then track down the wiring that corresponds to that pin, but I imagine the info is out there. Not finding it in Bentley right away.
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Old 03-23-2017, 06:01 AM
7pilot 7pilot is offline
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Originally Posted by cmac2012 View Post
I'll do it. Not sure what to make of dielectric grease. I gather it has some insulating properties. I guess it wouldn't actually interfere with the electrical transmission in question but it is curious. Ah, just searched the question a bit, this fellow put some energy into researching the point:

https://www.w8ji.com/dielectric_grea...ive_grease.htm

Cliff notes version: dielectric grease will yield better results.

Another angle I'm thinking to pursue is to start it and immediately shut it off one morning and then do all the Motronic electrical tests as outlined in Bentley. Then I'll get it good and warm such that it won't start - it will usually go into a mode of not starting that lasts for a half hour or more. And then repeat the tests. Who knows, I might find a pin that behaves differently. Not sure how I'll then track down the wiring that corresponds to that pin, but I imagine the info is out there. Not finding it in Bentley right away.
I have used it as a contact protector for years and recently found out about its insulating properties. No Harm no foul, I figure.

Post the primary and secondary resistances for the coil... I bought a 325iS cheaply that eluded diagnosis...ran for 5 or so minutes, then bucked and backfired and then was a no start.
The coil resistances were not to spec. New coil fixed it.

You have already switched DME's so that I think would rule out motronics control units.

The fuel delivery system needs to be definitively ruled out.
I think that if you jumped the fuel pump power supply, and the pump(s) remain running after the engine quits, then you could rule out the pumps, the main relay, and the CPS.

The ignition switch in the column warrants a visual inspection for shorts, cracks.
m
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Old 03-23-2017, 01:06 PM
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Mein Auto: Two 1987 325i, 430K, 211K
Good advice and I'll do all of those checks. It gave me another (possibly false) bundle of hope yesterday. I spray cleaned the CPS harness connector, let it dry all day, hooked it up in the evening and drove around nearby for almost 3 miles, no hint of difficulty. Hard to imagine that would be the story. These symptoms did remind me of a drama I had with my dead car last Christmas, a sporadic missing/lurching, not quite as bad as this episode but not good. On that one I found the CPS cable and other wires with much insulation worn off and shorting on the pulley where it crosses in front of the block. I taped the hell out of them and pulled the bundle away from future harm with zip ties and the problem was gone.

I replaced the CPS on this still running rig a few years back when I was at the 300+K mark with one I got at a boneyard from a rig with 170K on the odo. I might have gotten some dirt/grease in at that time. The way you slip the male connector part through the bracket and plug it into the female part gives room to brush some crap into the mix. The problem was not changed by putting in the new CPS several days back, of course that has the male part, if there was junk still in the female side the problem could have continued.

I dunno, tonight I'll drive it again and then leave it idling in front, blocked in by my van for security, and see if it idles for 20 or 30 minutes with no stalling, something it would no way do recently. If it passes that test, I'll try a longer test drive.

But all of this has persuaded me to tighten up on various issues. Will clean the ground connections with some devotion here soon. Perhaps the anti-oxidizing stuff followed by spray and then grease would be the deluxe route. Will check the coil also. I may have lucked out on one thing, that bundle of green corrosion I found on the fuel pump wires under the back seat could have easily led to a stall one day, somewhere far from home, with me scratching my head endlessly about how to get up and running.

Too late now but I wish I'd done the ECU harness testing before I cleaned the CPS connector. Oh well.
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