Help with vbat and afr problem

[jadzwin]

Hello,

I have a problem with a Vems that one of mine friends has bought from DP Engeneering NL
It was assumed "PnP" solution for C20LET. However it doesn't work as expected. So I have added flyback diode, replace one of voltage regulators (used for MCU VRef) that regulate voltage to 5.2V not to 5.0V so Vbat readings were far from ok.

Hovever there is still a problem. The car runing ok with big injectors (620CC) but during high revs Vbat voltage drops by 2-3V and AFR readings are very strange (>2000).
Actually there is external coil pack with ignition aplifier driven by stepper mottor driver. The voltage drop is higly correlated with dwell time. And strange AFR reading seems to be correlated with the low voltage.
The voltage between +12V and chasis seems to be stable and is 13.5V (it was measured with voltometer by car owner)

I run VEMS on my table with coils and there is no voltage drop at all (no WBO and injectors connectes). All drivers seems to work ok (I've check them with the scope), the current drawn by vems with no externel devices connected is about 150-160mA the same as in other vems I have.

What do you think what is the problem (especially with AFR reading) ?

Today I will check WBO configuration and wiring of Motronic connector to the PCB (big mess there lots of thermal glue :( ).

The biggest problem is that car is 200km from me and actually I have no possibility to measure anything :(

One more thing. The coil pack +12V is connected into orginal harness where the single coil was connected. Ground of coil pack is connected to battery ground.

Cheers
Kuba

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Have you spoken to DP about this?

[jadzwin]

The owner has talked with them (he isnt electornic skilled), and he want to repair (?) Vems in Poland.
I've just get phone number to them so I'm going to call them by myslef.

However I want to know your opinion what can be wrong...


Here is a log where can you see the problem:

[[email protected]]

Sorry for the late response, the Show unread posts since last visit link seems to miss occasional posts :(

Can you get the guy to put a DVM across the alternator and perform the same test - it could be that the voltage genuinely is dropping, and the injector voltage correction is having a large effect.

That lambda spike looks like fuel cut which would be correct if they've come off the throttle.