Please help with HPDI issues

Stilletto

Cadet
Joined
Jul 14, 2025
Messages
18
Got it in today, haven't had a chance to install it yet. If it doesn't solve the issue, the same seller has tons of mint parts that I may need also.
Very impressed.1000018355.jpg1000018356.jpg
 

Stilletto

Cadet
Joined
Jul 14, 2025
Messages
18
Didn't work.....runs the same exact crappy way.
I noticed that when I pull several spark plug wires, there isn't much/and effect on the way it runs even in gear
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,179
those motors limit RPM in neutral by cutting off more cylinders that just the 2 it drops in neutral
make sure the motor knows when you put it into gear.
it may not be getting the signal it is in gear
 

Stilletto

Cadet
Joined
Jul 14, 2025
Messages
18
I also noticed that if I pull each injector wire (one at a time) the rpm picks up and smooths a little. This suggests to me a global over fueling situation, or inconsistent spark.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,179
what tells the ECU the motor is getting proper fuel on these motors?
does it have an O2 senser?
maybe nothing.
it depends on the High pressure pump regulator to have the correct pressure.
did you make sure the ECU knows when it is in gear yet?
 
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