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View Full Version : Attn: Gurus, Experts and Psychics 4 help on NO-Start issue - Need new ideas.



Jeff in MN
01-01-2008, 02:37 AM
This is for my 87 535is with M30 motor. I have Bentley and been thru it 3 times as well as been thru Rick No-start shark page.

Two weeks ago son was on the expressway with cruise ON. Hit brakes to turn of cruise and she totally shut down. Coasted to stop. $122 tow job later in our garage we have the following:

Primary problem - I cannot get SPARK.
Engine cranks.
Battery charged.
Main relay checked - OK - replaced with good spare.
Fuel pump relay checked - Ok - replaced with good spare.
Fuse 5 looked bad and was replaced. (Checked all other fuses)
OBC relay checked and found ok. (interesting write up on Rick's no start shark)
checked voltage at coil when ON - OK.
Resistance between 1 and 15 on coil .5 to .6 ohms
Resistance between 14 and 4 (center) 5300 ohms.
Swapped coils with spare and confirmed ohms are same. (Even checked against same type coil in my 528e.)
Replaced cap and rotor with spares and ohmed - All ok.
Checked reference sensors both read the same 890 ohms between 1 and 2.
Reference sensors produced 1-2 millivolts when cranking when measured at the terminals at the ECU.
Measured for voltages at ECU harness as prescribed by Bentley and found all to correct.
Injectors are pulsing.
Purchased spare ECU from reputable ebayer. Installed yesterday - Still No Spark.

That's about all I can think of. Thanks in advance.
Jeff in Minnesota.
JUST GOT in from the cold garage. You won't believe it. During a clean and then a later replacement of the distributor cap I began to notice that the ROTOR was in exact same place. ODD!!!.. Pulled cap and cranked. ROTOR NO MOVE. OMG!!! Pulled the cam cover and found the chain and jumped off the camshaft gear. Somebody please tell me this is NOT an interference engine (3.5L M30). Naturally I will be posting again for parts and some guidance on an engine R&R. Thank to all for your help. BTW I now have a spare 059 ECU if anyone is interested.

Jeff in MN
01-01-2008, 04:43 AM
should be getting more then a couple mv out of the crank sensors, depending on cranking speed the speed sensor should be .5-1 volt AC, the ref sensor is hard to judge the reading as it only pulses once per revolution, one way to test it is to swap positions with the speed sensor and compare the readings, the speed sensor reads the starter teeth so it produces a higher voltage

Been leaking a lot of oil in that area, probably time to pull them and clean them up. However, what confuses me in the "instant" failure at the time he put on the brakes. Engine had been running great right up to that point.

Thanks for the suggestion.

Tiger
01-01-2008, 08:09 AM
That is the most probable cause of no spark... the crank position sensor... Otherwise, I might think your brake pedal switch is bad too... causing your cruise control to keep it off.... or something else off.

Jeff N.
01-01-2008, 08:49 AM
Curious. I'd sure be looking at the CPS / reference sensors too. On the E34, you have to make sure it's gapped to 1mm from the triggering wheel. Might want to verify the gap and alignment of the sensor.

I had a strange problem once when the bolt holding the CPS was loose. Couldn't really see anything wrong but it was obvious once you starting checking the unit itself.

Jeff in MN
01-01-2008, 10:48 AM
should be getting more then a couple mv out of the crank sensors, depending on cranking speed the speed sensor should be .5-1 volt AC, the ref sensor is hard to judge the reading as it only pulses once per revolution, one way to test it is to swap positions with the speed sensor and compare the readings, the speed sensor reads the starter teeth so it produces a higher voltage

Thanks.

Jeff in MN
01-01-2008, 10:49 AM
That is the most probable cause of no spark... the crank position sensor... Otherwise, I might think your brake pedal switch is bad too... causing your cruise control to keep it off.... or something else off.
Thanks Tiger.

winfred
01-01-2008, 11:18 AM
should be getting more then a couple mv out of the crank sensors, depending on cranking speed the speed sensor should be .5-1 volt AC, the ref sensor is hard to judge the reading as it only pulses once per revolution, one way to test it is to swap positions with the speed sensor and compare the readings, the speed sensor reads the starter teeth so it produces a higher voltage

Jeff in MN
01-03-2008, 03:20 PM
This is for my 87 535is with M30 motor. I have Bentley and been thru it 3 times as well as been thru Rick No-start shark page.

Two weeks ago son was on the expressway with cruise ON. Hit brakes to turn of cruise and she totally shut down. Coasted to stop. $122 tow job later in our garage we have the following:

Primary problem - I cannot get SPARK.
Engine cranks.
Battery charged.
Main relay checked - OK - replaced with good spare.
Fuel pump relay checked - Ok - replaced with good spare.
Fuse 5 looked bad and was replaced. (Checked all other fuses)
OBC relay checked and found ok. (interesting write up on Rick's no start shark)
checked voltage at coil when ON - OK.
Resistance between 1 and 15 on coil .5 to .6 ohms
Resistance between 14 and 4 (center) 5300 ohms.
Swapped coils with spare and confirmed ohms are same. (Even checked against same type coil in my 528e.)
Replaced cap and rotor with spares and ohmed - All ok.
Checked reference sensors both read the same 890 ohms between 1 and 2.
Reference sensors produced 1-2 millivolts when cranking when measured at the terminals at the ECU.
Measured for voltages at ECU harness as prescribed by Bentley and found all to correct.
Injectors are pulsing.
Purchased spare ECU from reputable ebayer. Installed yesterday - Still No Spark.

That's about all I can think of. Thanks in advance.
Jeff in Minnesota.
JUST GOT in from the cold garage. You won't believe it. During a clean and then a later replacement of the distributor cap I began to notice that the ROTOR was in exact same place. ODD!!!.. Pulled cap and cranked. ROTOR NO MOVE. OMG!!! Pulled the cam cover and found the chain and jumped off the camshaft gear. Somebody please tell me this is NOT an interference engine (3.5L M30). Naturally I will be posting again for parts and some guidance on an engine R&R. Thank to all for your help. BTW I now have a spare 059 ECU if anyone is interested.

Hmmm maybe my son did let the oil get to low a few weeks ago.