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Utter refusal to run at reasonable AFR's, noise problems


Xnke

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Check your injectors; look for a 36V spike or so at the end of the injector pulse. it SHOULD be there...if it's not, then it's getting shunted into something else.

 

The biggest noise issues with MS-V3.0 are INSIDE the box! As long as you are running shielded wiring for the RPM input, and your coil and plug wires are not across your sensor wiring, then the biggest noise contributors are going to be the alternator and then the PWM flyback circuits installed on the mainboard...the PWM idle circuit can also contribute.

 

The PWM flyback circuits draw power directly from the same pin that feeds the main processor!

 

I have definitely shielded my RPM wheel sensor cable and separated my bundles so the coil driver and injector drivers are not in proximity.  I am not using idle PWM as I am just using a Nissan electric idle bypass, it closes after it warms up with straight 12V.  I have also tried to take the high current ground side of the connector and use that only for chassis and the drivers, and use the other side of the ground section for sensors only. It should be as noise free as possible externally.  I have an oscilloscope now, so I will be probing this stuff tonight.

Edited by SleeperZ
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Just tossing my two cents out there regarding noise. The only time I had problems with noise and MS resetting was when I had my ignitor mounted on the MS board. I put a cap on the boot header, did the injector PWM fix, nothing helped. Then I moved the ignitor outside and all the noise went away.

 

So a simple fix might be to run a separate ground to your ignitor. Disconnect the ground leg from the board and run a wire from the ignitor straight to the engine block.

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Just tossing my two cents out there regarding noise. The only time I had problems with noise and MS resetting was when I had my ignitor mounted on the MS board. I put a cap on the boot header, did the injector PWM fix, nothing helped. Then I moved the ignitor outside and all the noise went away.

 

So a simple fix might be to run a separate ground to your ignitor. Disconnect the ground leg from the board and run a wire from the ignitor straight to the engine block.

 

That is a very interesting suggestion.  I originally planned it out to use an external ignitor, I have the stock L28ET coil and ignitor.  Then when I built my MS3 box, I just decided to go with the internal high current driver even though there is no control over the ground current.  But if I need to, it should be simple enough to rewire the ignition circuit to keep the ground return current from the coil out of the MS3 box.

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