Author Topic: Cam signal error inside ECU  (Read 210 times)

Offline Dissembler

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Cam signal error inside ECU
« on: July 30, 2019, 06:51:38 am »
Having a very wierd issue with my ECU. All started about a month ago, engine was running fine, then developed a dead miss and now it basically doesn't run at all. Have "too many primary trigger" error. Have traced the problem to an issue with cam sync. New cam sensor, new wiring harness and verified with oscilloscope that the signal at the ecu connector is proper. Engine is 91 BMW M42, plug and play VEMS

The wierd thing is that if I do a complete config file upload, my triggers look perfect. Engine will fire up, run for about 5 seconds, then primary trigger error flashes, engine stalls and won't try to fire at all. Run the trigger log, and it shows a 2 on 2 off pattern with cam sync (trigger log shows 2 full crank revolutions with no cam signal, then the next 2 crank revolutions BOTH have a cam signal) and nothing I do can fix it. Do a complete config upload again, trigger logs look good, engine fires up, stalls and cam sync fails again.
« Last Edit: July 30, 2019, 06:59:39 am by Dissembler »

Offline Dissembler

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Re: Cam signal error inside ECU
« Reply #1 on: July 30, 2019, 06:57:19 am »
I want to attach the trigger logs but no option to do it, maybe because my post count isn't high enough? I've had my VEMS for 3 years or so and have lurked around here but never joined

Offline Kamuto

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Re: Cam signal error inside ECU
« Reply #2 on: July 30, 2019, 03:16:12 pm »
Having a very wierd issue with my ECU. All started about a month ago, engine was running fine, then developed a dead miss and now it basically doesn't run at all. Have "too many primary trigger" error. Have traced the problem to an issue with cam sync. New cam sensor, new wiring harness and verified with oscilloscope that the signal at the ecu connector is proper. Engine is 91 BMW M42, plug and play VEMS

The wierd thing is that if I do a complete config file upload, my triggers look perfect. Engine will fire up, run for about 5 seconds, then primary trigger error flashes, engine stalls and won't try to fire at all. Run the trigger log, and it shows a 2 on 2 off pattern with cam sync (trigger log shows 2 full crank revolutions with no cam signal, then the next 2 crank revolutions BOTH have a cam signal) and nothing I do can fix it. Do a complete config upload again, trigger logs look good, engine fires up, stalls and cam sync fails again.

thinking, is there such thing as M42 plug&play?
Vems installer in Lithuania
valdas.sunokas@gmail.com

Offline gunni

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Re: Cam signal error inside ECU
« Reply #3 on: July 31, 2019, 12:17:44 am »
There is a M42 pnp

OP - you might want to look into the distance between your cam sensor and the trigger on the inside. I´ve had that before, you might have to fit a resistor between the two VR signals to bump up the voltage coming through

Offline Dissembler

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Re: Cam signal error inside ECU
« Reply #4 on: July 31, 2019, 03:17:07 am »
Thanks gunni, will give it a try. How much of a resistor would you recommend?