Howling '89 325

I have a problem with my 1989 BMW 325i. Lately I will be driving down the freeway (rarely but does happen on surface streets) and the car will suddenly lose all power. There is no indication that it is about
to happen but when it does the is a howling sound coming from the exhuast. If I pull over it will still be idling and I can slighly rev it if I press on the gas. This increases the howling sound. If I don't pull over and I press on the gas, the car doesn't rev and continures to slow down (with other cars passing me on right and left). While on the freeway, I have to put it in nuetral (it is an automatic), turn it off and then re-start it, put it back in drive, and continue on. Restarting it seems to cure the problem. If I have been driving for a while and it happens, it is much more likely to do it a second and third time. This isn't very safe. I took it to a repair shop and they couldn't replicate the problem and said it was probably a transmission problem. I didn't think it was but I took it to a transmission shop anyway and they said the tranny was in perfect condition. I am not sure if it is an electrical problem or something mechanical in the fuel system. The other day, it did it after went over a major bump. But it happens on smooth road as well. The howling sound is unlike anything I have heard from a car. Sounds like a dog howling coming from the exhuast. Last night I replaced the fuel pump and then it did it again this morning. I also added some fuel system cleaner but I doubt it will solve the problem. I was thinking maybe it could be the fuel pressure regulator since it will still idel but won't rev. Although I don't know why it would be howling. PLEASE HELP ME!!!!!! I don't want to get ride of this car because when it isn't doing this it runs beautifully and get up to 27 mpg even with 186k miles. Any suggestions would be extremely helpful.
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MechEMike wrote:

I think you have two problems. I'd replace the fuel pump relay and Motronic relay to solve the driveability problems. They live under the long black strip of plastic in front of the windscreen.
As for the howling it's either a bad fan belt or a badly tensioned timing belt (NOT good).
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I had a problem on my '84 318i where the engine would lose all power accompanied by what I called a squawking howl sound coming from the exaust manifold side of the engine compartment. It only occured after the engine had been completely warmed up and would be temporarily fixed by turning the engine off and restarting it, so your problem sounds somewhat similar. When the problem first arose it would only happen at fairly high engine rpms but as it got worse the rpm threshold got lower and lower until the car was completely unusable. I finally found it when it got so bad that it would do it when the car was idling. It turned out that the bushings in the distributor were worn so bad that when the oil got thin from being completely warmed up that the distributor shaft would 'whirl' in the clearance and that the resulting vibration would cause the ignition electronics to malfunction. Whirl means that the shaft was trying to roll around inside the oversized bore instead of just rotating within it, sort of like a marble rolling around inside of a bowl. My 318i had 256k miles on it when this happened so I figured it was not unexpected for the distributor bushings to be worn out, but I had taken it to a BMW dealer and an independent with the problem and they couldn't find it either; probably because they seldom work on anything with over 100k on it. Anyway, I hope this helps you.

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If it happens after a bump that would suggest it is electrical, like a loose wire or connexion somewhere. Maybe check connexions for the fuel injection and anything to do with the engine management systems/sensors. Maybe you or someone didn't plug a connector back in properly after doing something on the car? Might also be a short somewhere, recurring when you go around a bend in a certain way (or hit a bump). I once had a car that would die whenever the keys on my giant key-ring touched a metal fitting on the dash while driving. It would short out a fuse due to a dual fuel system being wired up wrong. I had similar problems to yours on another car and it was a wire to the coil shorting out on a manifold. I think E30's also have a couple of speed sensors around the top of the bell-housing that have something to do with ignition timing. Sometimes there are sensors in the diff too, but I think only for the speedo?
Best of luck,
Steve

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