Sudden Death

So I was driving the 1991 535i/m in some very hot weather the other day. With the AC on, the idle speed started jumping up and down by 200-600RPM or so. Sweet. The next day, on acceleration onto the freeway, someone hit the off switch. Idiot lights lit, motor died instantly, pulled off the road and got AAA-ed home, which was luckily like 5 miles.

There was no stutter, no stumble, no cough. Just a motor that did 3500RPM to 0RPM inside of a blink of an eye.

The CEL throws a clear "1444;" starter cranks healthy and motor turns over just fine, just no starting or running.

I just moved and my Bentley's buried someplace. This could be so many things. Any ideas? TPS? ICV? Both? I've had no electrical issues up til now. Fuses are fine. Battery's new and seems to be powering everything.

I had momentary near death experiances like that, and I traced it down to the ground wire between the chassis and the block.

On older 5 series main and or fuel relays fail instanter. Fuel relay could be swapped w/ horn relay, whack main relay w/ screwdriver handle and see if it wakes up.... course on a '91 I could be way off base too..
Tom

Is the fuel pump running? Are you getting spark?

DME relay i would assume, BMW recommends having a backup one in your car at all times.

My fuel pump died like that. You can easily check if it is a fuel pump by spraying carb cleaner or something inflammable into the intake while somebody else is engaging the starter.
In my case mechanic sprayed something called "Rapid Start".

cps?

The POS hyundia I had did exactly the same thing, and the starter fluid trick helped us track it down pretty fast. Either you are not getting fuel or spark, and the fluid guarantees the fuel part of that equation.

BTW, I got to personally witness the death of the worst car I ever owned ( I wanted to see it burn) and finally got back to BWM's.

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Originally Posted by Airborne001

The POS hyundia I had did exactly the same thing, and the starter fluid trick helped us track it down pretty fast. Either you are not getting fuel or spark, and the fluid guarantees the fuel part of that equation.

BTW, I got to personally witness the death of the worst car I ever owned ( I wanted to see it burn) and finally got back to BWM's.

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And what kind of a car it was that you executed it by burning to death? :D

OK, all good hints. It's parked now, and hopefully I'll have time soon to track this mofo down...

A black 2000 hyundai elantra. I only kept it so long because I wanted to be personally responsible for killing it. It was a personal kind of thing.

Finally got a chance to look at it. If I take the wire from the coil off the distributor and stick the electrode near something metal and turn it over, I get nothing. Clear indication of no spark, eh?

Time to go crawl around and see about that ground wire. How can I test the DME relay that was mentioned?

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Originally Posted by Derek A.

Is the fuel pump running? Are you getting spark?

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Eliminate one of these two and go forward from there.

Verify you have no injector pulse as well as no spark. If you are missing both, then look for problems that relate to both fuel and spark, such as bad CPS. If you dont have a noid light or high impedance ohmeter, you can often just listen to, or place a finger on the injector while an assistant cranks to see if it is clicking.

No starts pretty much all start the same way, check for both spark and fuel, it makes a difference in diagnosis if you have no spark, no fuel, or neither. Cover all the basics first before moving to exotic things. Check ALL the fuses with a test light on the back of the fuse, make sure you have power to the coil and injectors etc.

let us know what you find.

Finally was able to dig out the Bentley. I didn't test for spark the right way, so I'll do that again once I have someone to turn the motor over. All the fuses test fine. My cheap ohmmeter appears to be malfunctioning as I can't get it to read any resistance at the harness connector for the CPS, or anywhere else for that matter, so I can't say much about that just yet...

Sad to say this has been one of "those" cars since I bought it in the spring. Hopefully we'll get all this business ironed out together soon...

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Originally Posted by Kristuphir

Finally was able to dig out the Bentley. I didn't test for spark the right way, so I'll do that again once I have someone to turn the motor over. All the fuses test fine. My cheap ohmmeter appears to be malfunctioning as I can't get it to read any resistance at the harness connector for the CPS, or anywhere else for that matter, so I can't say much about that just yet...

Sad to say this has been one of "those" cars since I bought it in the spring. Hopefully we'll get all this business ironed out together soon...

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Ahem. (main relay) Did you rap on it?

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Originally Posted by joshua43214

Verify you have no injector pulse as well as no spark. If you are missing both, then look for problems that relate to both fuel and spark, such as bad CPS. If you dont have a noid light or high impedance ohmeter, you can often just listen to, or place a finger on the injector while an assistant cranks to see if it is clicking.

No starts pretty much all start the same way, check for both spark and fuel, it makes a difference in diagnosis if you have no spark, no fuel, or neither. Cover all the basics first before moving to exotic things. Check ALL the fuses with a test light on the back of the fuse, make sure you have power to the coil and injectors etc.

let us know what you find.

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Ding! I borrowed a friend's "real" multimeter and the resistance at the CPS harness connector was roughly 200 times what it should've been. I just installed a new one today, and it started right up! (with a jump...the stupid flashing alarm light the PO had installed drained the battery during the car's downtime, I guess).

Thanks for pointing me in the right direction!

Its either fuel or spark. but if it happened while turning off the a/c it possible it could be a electrical problem. Try swapping relays for fuel and ignition and also check every fuse and fusable link, under the hood and under the rear seat.