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MS3 Ignition Issues


SleeperZ

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You're running resistors for each of those low impedance injectors right?

 

Of course not.  I am using PWM so I can open them quickly with full voltage and hold them on with a lower voltage.   Using resistors with low impedance injectors is defeating the purpose of having them.

 

I have done some re-wiring.  I added some tantalum capacitors across the PWM circuits, and the 12V is pretty stable even during PWM, I get maybe 0.5V of variation.  I also routed the grounds for the injector MOSFETs directly to the DB37 connector.  The periodic missing is decreased, as a matter of fact it's completely gone until the engine reaches operating temperature, but it still kicks in.

 

I don't know yet how I am going to fix this.  When I get time, I will continue to probe the signals with my scope to see if I can pinpoint the issue.  It's a huge pain in the a$$, I certainly did not anticipate this level of difficulty with what's supposed to be a developed product.

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Alright alright, I know that low impedance injectors are a tiny bit faster than high impedance. I was just making sure you didn't wire them straight into the MS like you would with high z injectors. That'd be a good way to run too much current through your board.

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Alright alright, I know that low impedance injectors are a tiny bit faster than high impedance. I was just making sure you didn't wire them straight into the MS like you would with high z injectors. That'd be a good way to run too much current through your board.

 

I do appreciate your feedback.  You are right, I suspect the weak points in this ECU design are related to current, and with 6 low impedance injectors I may be pushing its capabilities.  I might be able to fix this whole damn thing by simply adding resistors and killing the PWM - I hate to admit defeat, but reality does not care about my ego.

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