Author Topic: Anomaly with cold starts  (Read 279 times)

Offline H.E

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Anomaly with cold starts
« on: December 01, 2018, 11:40:17 pm »
Hi all,

I have a genboard V3.8 that is running a hybrid engine of BMW M52TUB28 (block), M52(vanos and cams) and M50 (intake).
I'm having problems to start the engine after it has been standing for a while. There is a correlation between the magnitude of the problem and the time it has been standing.
1. I turn off the car.
2. I turn on the ignition after 12hours. The 5v output is fluctuating around 2-3V, so MAP, TPS and Hall crank position sensors are affected.
3. I wait for about 30sec to 2min. The 5v output jumps to normal and fuel pump primes once more. (Recently it has got a lot colder, from +10 to -5 and either this or maybe just time has made it recently a lot worse). Now if I try to start the engine, everything seems to be in order, but the car struggles to start.
4. I now wait again for about 1-2+ minutes and the car starts perfectly.

There are no log differences in cranking after the 5v output gets to normal.
I do not have a oscilloscope to verify what is causing the starting problem after the 5v jumps to normal, but maybe someone has ideas to check?

I bought a V3.8 genboard and the plug with casing. I'm using VEMS 250 external 3-wire MAP sensor.
Thanks for all the ideas!

Offline Kamuto

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Re: Anomaly with cold starts
« Reply #1 on: December 02, 2018, 06:07:41 am »
check by disconecting sensors, btw, bmw should have 12v on cam and crank, not 5v :)
Vems installer in Lithuania