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Perplexing Problem Starting my 87 528e

3K views 5 replies 3 participants last post by  arkhaus 
#1 ·
:confused: I have searched the Forums and can not find a similar description to this one so PLEASE HELP!!

I have a 1987 (prod date 7/86) 528e, 380,000+ miles, that has developed a perplexing problem. She has been in the family since she had 57,000 miles on her so we are intent on keeping her going -- I want to see her roll over 1,000,000 miles.

In April we replaced the coil, distributer and rotor button.

In May 2005 the transmission went out (375,000 on the original) and in July we had it shipped to Arizona to be remanufactured. Due to some confusion on the part of my mechanic and the shippers it didn't make it back into the car until mid September. While the car was in the shop I had them replace the timing belt, adjust the valves, new plugs, etc.

The car ran absolutely perfect (my son drives her daily to school, work and play) until mid November when after a rainstorm we discovered that there is a windshield leak (faulty windshield install from a cracked windshield replacement) that allowed the ECU to get wet. We discovered the leak when my son went outside to go to school and the car would not start.

That afternoon when it had dryed out it started it had the problem I describe below:

To get it to run correctly requires several starts. By this I meant that anytime (and I mean anytime -- hot, cold, time of day doesn't matter) you start it we will start it and it will act as if the timing is very, very wrong or the mixture is extremely rich -- very slow/poor idle, no power, backfires, sputters, and if left to idle for long the exhaust manifolds get extremely hot (read glow red), exhaust smells indicate that mixture is way too rich. Shut it off, try again, repeat, after an indeterminate number of starts she will run great -- full power, perfect idle, manifolds normal temp, exhaust is normal and in general life is BMW good.

Troubleshooting results:
O2 sensor disconnected has no impact on the problem.
AFM disconnected the car won't start at all.
Cold start valve tests okay.
I have swapped ECUs with a New Old Stock one and the problem persists.

The following components have been replaced since the problem started:

1. The idle control valve, -- it wasn't working see #2 below

2. The idle control module (it was bad -- broken internal ribbon cable)

3. The main fuel pump (one night in mid December it wouldn't start at all with no fuel being delivered to the engine) a quick relay jumper check determined that there was power to the pump but the pump was not running.

4. The fuel filter

5. The fuel pressure regulator

6. The entire exhaust system from the head pipes back -- the system had rotted out sitting on the ground at the shop waiting for the transmission to return from rebuild.

7. The speed sensor.

8. The starter -- it was the original and all the repeated starts finally killed it.

In the 24 hours before the main fuel pump failed the problem went away and she would start perfect the first time. Once the fuel pump failed and was replaced the probem returned.

I am ready to throw in the towel and take it to the shop but since I worked on automobiles and trucks in my grandfather's garage (he retired 10 years ago) since I was old enough to read and understand wrench sizes I prefer to fix it myself. Any suggestions are welcomed and appreciated.

Thank you

Mike Whetstone
 
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#4 ·
Possible Resolution

Over the holiday weekend I believe that we have tracked it down to a worn out Mass Airflow Sensor (MAS). I decided that it might be corrosion problem in the wiring and started cleaning all the connectors. We would try to start the car after each connector so if we resolved the problem we would have it isolated.

When we popped the top on the MAS there are areas on the sweep that are clearly worn out and where the two connectors sit on the circuit board under the connectors looked like a set of pitted points (for those of you old enough to remember points). I cleaned them up and cleaned the entire top circuit and the connector with some electronic circuit cleaner from my shop and like magic the problem was gone for about 3 hours. When the problem returned the pitting was back underneath the connectors. Quick clean and the problem is gone again temporarily.

I am trying to find someone locally with a known good one that I can swap out to try before I buy.

If this works I will let everyone know.

Mike
 
#5 ·
Related problem....

Do you seem to have the most trouble starting the car after it rains and/or damp weather? I have a 1995 525i that will not start after a heavy rain/damp weather. Had many of the parts you mentioned below replaced...Fuel Pump, Regulator, etc. I'm taking it back to the garage today - 4th time in 5 mos.

Please let me know if the MAS solves your problem. I had a very similiar experience (as you are describing) with my Land Rover. They replaced the MAS and it runs great.

Good luck,
Eric
 
#6 ·
We are getting closer, but still no cigar.

We have now additionally replaced:

Mass Airflow Sensor

Engine Temp Sensor (fell apart when we were checking the wires)

Coolant Temp Sensor (just because)

Transfer fuel pump (it was bad)

On board computer

O2 wiring connector

We have also cleaned the bottom of the under hood fuse box.

As part of our troubleshooting we have determined that when the car does not start correctly the Idle Control Module is not sending a signal to the Idle Control Valve. When the Idle Control Module sends a signal to the Idle control Valve the car runs perfectly. So we have narrowed down the culprit but not the cause.

With all this work the car now starts in fewer tries than before -- it still takes several cranking/starting episodes before it starts correctly.

I have ordered a replacement cold start timing sensor that is supposed to be in today -- even though the cold start injector is working correctly.

Since we replaced the ICM, I believe that it is wiring.One major reason that I believe it is wiring is the behavior of the On Board Computer (the one in the dash, not the ECU) -- it has stopped lighting up when the car is started. It is working because from certain angles you can see the numbers in the display but the backlight is not working (the bulb is good -- we tested it) and it frequently blanks out as if it lost power and when it comes back on it is reset to German.

According to a schematic that I have one of the signals to the main relay runs through the on board computer so it could be a contributor to the problems we are seeing.

Earlier this week when my son was on his way to school in a rainstorm the car just shut down. After sitting for 30 minutes it started up (multiple tries to get it running correctly) so I will also be replacing the coil today.

I am off to parts store.

Mike
 
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