Just got my swap finished and driving. Drove to the gas station (about 1/2 mile) to fill it up. When I went to leave the car would not start. it turned through but no fuel or spark (speculative). Had a freind run back to the shop to get tools and parts. checked for loose wires to no avail. after approx 5 min, tried the car again and it cranked. I then drove the car back to the shop to look over things. tried to crank the car again and it would not run. then I went to the office got on R3v and started to read others posts. I could not find anything similar. guys either thier car would not crank (starter) or it would not fire (ecm or relay or CPS). When My car runs it runs and drives great. After looking online I decided to call it a night and went to push the car out and decided I would try the car one more time. it cranked. what could be the problem? any help is appreciated. thanks.
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Sounds like a relay is failing. Swap the master and then try that. Easy two second item and they do fail. -
Which engine and electronics?Comment
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Oh, My bad. The car is an 87 325i. the engine is a 1994 m50 w/vanos. s50 cams and trm chip.
I tried swapping a couple of relays. the main relay and the fuel at different times and it did not help. Not saying I dont have two bad main relays...
I am thinking it may be an issue with the ecu. what sends power to the DME? where does the DME get ground?Comment
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Ok. new development. I have noticed when the car is going to crank and run, approx. 1/2 sec before firing up, the check engine lights up and then immediately goes off. when it does not fire up the check engine does not light up.
the no start fault happens when it is warmed up. What could cause this?Comment
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It might be a faulty crank position sensor. They tend to have a failure pattern of working fine with cold start, but failing when the engine gets warm.
Is the engine harness diagnostics port intact? Get the fault codes read.Comment
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I just replaced the crank sensor. that is what was keeping it from working initially. Not saying this is not the problem, i have known new parts to be bad.
Where is the diagnostic port. Is that the large plug that resides on the passenger side of the firewall from the e36 harness? What do i need to read it, or should I take it to a BMW mechanic?Comment
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Yeah that's the plug. Since it's pre-OBD2 you need a BMW mechanic's help. Getting fault codes read at dealer isn't expensive though.
I check stuff on my '95 via Carsoft 6.5 with an old laptop and a cable I bought from Ebay, works great and even shows live data. Carsoft stuff can be flakey tho so YMMW.Comment
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Ok, I took my car to a friends house to do some diagnosing. He is a BMW tech and had access to a GT1 type software laptop. we plugged it in and the engine coolent temp sensor is the only thing that seemed to give bad values. when this happens the DME substitutes a value and just runs with it. then we tried a couple of things like unplugging the sensor to see how the readings would react. they did alot of nothing. all of these test were run with the engine running. then we turned the car off and attempted to crank it and the car would not fire just as before. then we noticed the DME was not communicating to the GT1. it seems there is something in the computer that is "timing out" or is getting too hot and is not sending out signals. My thoughts are there is some type of "relay" in the DME that once latched is creating alot of heat and once unlatched it does not want to work due to the heat. I have now replaced the DME and it seems to work fine I am going to drive the car home for the first time hopefully it will crank for me when I go to the gas station to fill up this time.
Hopefully if someone else runs into this problem my thread will help them.Comment
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and 8 years later... did the dme solve the problem?
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