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Fuel injector drives grounding temporarily on ECU on/off


jycheung
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Link G4+ storm

Is it normal for the injector drives to be temporarily grounded on ECU on and off?

ECU and injectors are wired to same +12V on PDM.

Oscilloscope shows injector drives reaching ground potential temporarily with ECU on and off.

 

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No it would not be normal for a storm as the only way the injector drive can drive to ground is if the mosfet is excited (ecu micro needs to be powered).

Why does the scope show 3V when on?  It should be 12V?  What is the actual problem you are trying to solve?

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Oscilloscope is measuring voltage difference between injector drive and ground.  I’m assuming it’s a floating voltage when not the injector drive is not firing.  
 

the issue is - 
I had a fuel injector back feed issue when the injectors were wired separately to a different pdm output and they were staying open after ecu was powering down.  I rewired injectors to have same pdm output as the ecu to fix the issue   Which I think it has   

haven’t had any more flooding but I do notice what I think is some fuel in the sitting in the cylinder bore in the valve pockets of of the piston when I scoped the bores recently.  When I power on the ecu I also hear some clicking x 1 from the injectors.  I’m just wondering if for whatever reason injectors are opening temporarily on ecu on and off.  

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9 minutes ago, jycheung said:

Oscilloscope is measuring voltage difference between injector drive and ground.  I’m assuming it’s a floating voltage when not the injector drive is not firing.  

So there no injector connected when you done that scope?  In that case yes, it is just floating as you have no injector "pulling it high".

 

10 minutes ago, jycheung said:

I had a fuel injector back feed issue when the injectors were wired separately to a different pdm output and they were staying open after ecu was powering down.

I dont think the Storm injector drives can backfeed, only the ecu's with P&H injector drives as far as I know.  The Storm uses the same drivers as our plug-in ecus and in many of those the factory wiring has the injectors or other relays switched by injector drives live all the time and dont backfeed.    

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