LBZ: Help! No one can figure out the issue.

[stibuilder]

This is in no way a dig on the shop working on my truck but a huge request for thoughts on what to do to fix it. Everyone is stumped!

Attached is the work order showing what has been done seems like they have seen exactly what i have seen but haven't been able to figure out whats causing it.

HELP!

 

[1FastBrick]

Sounds like there is an electrical issue on #8.

Any chance you have another engine harness to try?

 

[stibuilder]

Replaced the engine harness with one from another truck already.

 

[Budneeds2beers]

Any splices in harness? Maybe something is inducing noise or maybe a grounding issue? Man this is a tuff one.

 

[1FastBrick]

Ok, have you tried un-plugging the aftermarket stereo equipment and any thing electrical that was not OEM???

Does it have an aftermarket alarm???

 

[Josh154]

And people think Subaru’s are expensive/tough to work on :roflmao: sorry I can’t provide much help hope you get it figured out man.

 

[stibuilder]

We could remove the power from the stereo equipment to see if that changes anything.

 

[stibuilder]

Bump, looking for suggestions.

 

[Chevy1925]

something is back feeding noise. From everything i have read, the GPCM disconnected should not let the truck start but maybe that is only LMM and up?

i see them testing voltage but have not ohmed the wiring. Mike and i were just discussing this yesterday. a broken wire with one strand still connected will show 12v but you wont be able to carry any amp load to make what ever it is that needs to be triggered, triggered. Amp tester will help here too.

has the TCM been swapped with a known good one?

 

[Hambone]

Both my Lly and LBZ have drivin without the gcpm so must be Lmm up

 

[Chevy1925]

Both my Lly and LBZ have drivin without the gcpm so must be Lmm up

good to know!

 

[SickLL7Crenshaw]

LMM will still start with GPCM disconnected, or the truck I was chasing voltages problems with it disconnected.

 

[Wturnbo]

Buying new GPCM wondering if they need to be programmed to the truck?

 

[stibuilder]

This truck has a new GPCM that was programmed by the dealer to the truck since it kept producing a CEL for it. I could have them try running it without a TCM. Wondering if its worth the money for the compression test at this point? A friend has been comparing data from his Kodiak same year to logs to mine and he says my truck is flipping between 6 tables trying to run, and the fuel pressure is surging 500PSI compared to his truck that runs exactly the commanded fuel pressure.

In the fuel rails I have the two PPE race valves and both rails have the ported fuel rail fitting.

Electrical keeps popping up but having a hard time getting a good place to start.

 

[jlawles2]

PPE Race valves might not be seating correctly on the left side. At high commanded rail pressure its leaking.

 

[stibuilder]

PPE Race valves might not be seating correctly on the left side. At high commanded rail pressure its leaking.

Leaking externally?

 

[duck_156]

We have tried Stock tunes and different ECM all see to have the same issue. Here is a screen shots of what we see the truck doing. What I see even though the engine sounds and feel like smooth while idling its not it seems to be surging. I know this is hard to see but the truck is doubling the Pilot fuel flow every .5 seconds for some reason.

The bottom screen shot is from my truck. The only way I have been able to get my truck to hit a 2.2 pilot fuel flow is a full throttle hit and this truck is doing it at idle. What we have been unable to figure out if the high balance rate on #8 an issues with that cylinder or something else causing #8 to look bad. It differently has the 1500-2000 rpm fuel knock.

As stibuilder has said we have change / moved / tested or replace a ton of stuff and are totally stumped. Anyone got any good ideas that does not involve replace 8 brand new injectors?

 

[jlawles2]

The race valves are like the fuel pressure relief valve. They have been known to leak. Leak is internal to the rail and leaks into the return. Pull the return line and run it into a clear bottle. Drive the truck and see how much is in the bottle. With the race valves there should be none.

 

[gmduramax]

Two ported fittings and two race valves? Doesn't it only have one FPRV? Or are kodiaks different? Also didn't someone test ported rail fittings on a bench and they noticed a lot more noise from the injectors. I wish I could remember the thread but it's here somewhere.

 

[ChrisPerry]

I might have missed it, but have you swapped #8 injector with another one to see if the problem follows the injector?