Author Topic: Cooling fan causes trigger insanity - ABZ flywheel teeth triger?  (Read 3980 times)

Offline smurfinator

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If the fan is running and ignition on -engine not started- I can hear spark and injectors firing crazily and tach bumps up and down.

All ground are checked and re-checked per phatbob.
Fan is wired to chassis ground and alternator hot positive.
Crank sensor is shielded wire for about 18" then plain wires to ecu.

I should add that the ECU has it's own power wire straight to the battery and the fan chassis ground is not very near the ECU chassis ground.


Er... where do I start to look here?

Thanks!
« Last Edit: July 27, 2015, 09:34:05 pm by smurfinator »
Audi ABZ 4.2 V8 in 1993 90 quattro
TTV 60-2 flywheel and cam sync
firmware: 1.2.20

Smurf blue (BMW Laguna Seca), hence the name!

Offline smurfinator

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Re: Cooling fan causes trigger insanity
« Reply #1 on: July 27, 2015, 09:33:32 pm »
Roight, it appears that I have brainfarted how bad it is for the VR sensor to be 1/4" away from the fan motor, haha.

But in the 10 years I've been fooling with this car, I have found no other way to arrange these components due to space constraints.

Anybody have luck running an ABZ on the flywheel teeth?  I have no 60-2 on my flywheel... but camsynch works.

Audi ABZ 4.2 V8 in 1993 90 quattro
TTV 60-2 flywheel and cam sync
firmware: 1.2.20

Smurf blue (BMW Laguna Seca), hence the name!

Offline MWfire

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Re: Cooling fan causes trigger insanity - ABZ flywheel teeth triger?
« Reply #2 on: July 27, 2015, 11:04:28 pm »
imho just make good grounding for shield of vr sensor cable(2wire + shild). Ground should be only at vems side.

Offline VEMS

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Re: Cooling fan causes trigger insanity - ABZ flywheel teeth triger?
« Reply #3 on: July 28, 2015, 10:36:17 am »
Hello Ben,

Crank VR should use shielded wire (proper type preferably twisted pair with shield and foil) all the way up to the ecu, grounded shield grounded at ecu side only like MWfire suggested, implement/change this before anything else.

Best regards, Dave