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Ecu read 650rpm with fan ON

EFI Wiring Fundamentals

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I work on a ECUMASTER classic. The engine work only with Cranksensor. It is a reluctor bmw trigger sensor. With engine off, when I open the fan from the external switch, or from the ecu, the ECU read 650rpm and start to work the injector and the coils. I check the shield from the cable and it is ok. I try an external cable for the cranksensor but without any different. What other I can check to find a solution on that problem . I attach what the ecu read and a photo from the oscilloscope.

Also, When I have the ecu connected to the harness , I find that the shield ground from the ecu it is contacted with the ground of the car. Without ecu there is no connection.

Attached Files

Hello the issue is more likely to be in the ECU grounding not the trigger wiring check this first

regards Ross

That last bit is a little unclear. When using shielding, it is IMPORTANT that the shielding is only grounded at only ONE point - if at more than one point, it can introduce different ground potentials (ground loops) that may cause problems with some circuitry.

Today , I check the ECU ground. It is connected with the other grounds together. I relocate it separate to the chassis but there is no different. Also the shields is grounded in one point.

The ecu shouldn't be triggering with only 80mV of noise on the trigger wire. Doesnt it have some sort of trigger arming threshold type setting that you can set above the noise level?

The ecumaster didn't have trigger arming Threshold table like LINK. I find that I can check the pull up resistor on main trigger and I don't have this problem, but I have trigger error at 6200rpm, So I can not use it. I start to though that the solution is only to remove the fan switch, and to work from ecu only when engine work.

Attached Files

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