RonSSNova

iTrader: (3)

I had no clue GM produced such an animal.
I got a call from my engine guy who's customer has one of these bought at auction for $1500. They removed the CNG tank and wiring and it threw engine codes. Couldn't pass emissions, can you help?

So drove over and checked it out. Very unique. has two sets of fuel rails, two sets of injectors. Intake manifold not like the typical truck as it supports dual injectors per cylinder. Hmmmm

Read the tune no issues. PCM is a P59A gen 3 Hybrid.
I was able to turn off the offending codes, and it should have no issues with emissions.
They have been fiddling with it for a year...….

Truck was a fleet vehicle for Pacific Northwest Natural Gas. Imagine that!
Pretty nice drivetrain for $1500. 6.0 and 4L80E. Especially since it was likely run on CNG most of the time and prob serviced on a schedule.

No questions or anything, I just found it interesting.

Ron

G Atsma

I think I remember a CNG option, but had no idea how it looked. it likely was not cheap....

truckdoug

iTrader: (25)

Ron i hope you charged accordingly! anytime i fix something the customer has rolled snake eyes on, I charge the "i am a computer genius" fee

RonSSNova

iTrader: (3)

I did fine Doug!

rpturbo

iTrader: (47)

I had seen that as a option listed in car part when searching. I thought it was interesting also. Did you keep a coy of the tune? I wonder how it knew what fuel to run, or do you know if it was like the older cng units where it had a hard switch. They use to be required to start on gasoline, and then you could switch over, but I think you also had to swap back to gasoline before shutting it off if I remember correctly.

truckdoug

iTrader: (25)

i looked up the injectors for that application and it shows they flow 80+ lb/hr

dunno if the cng injectors would play nice with ethanol tho

RonSSNova

iTrader: (3)

I did save the tune. Always do.
This had a switch on the dash. So I assume there is an input to the ecu. Would have to have the pinout. Might be difficult to come by.

The tune showed a separate entry for CNG Stoich. 16.3 IIRC
Its also a flex fuel file, but flex fuel not activated. I didn’t look real close at the rest of it.
No custom operating system available with HPT.

Doug, there are CNG injectors that are popular with the turbo crowd. They work with E85. But are 220’s I believe.

Ron

gametech

iTrader: (1)

I have this vision of how you could ditch the cng tank and replace it with a methanol fuel cell. Wire in the boost controller switch to activate the fuel pump and cng switch to the computer. With a 4l80 already in the mix, it sounds like this guy got a hell of a deal on the truck, if it is in any kind of decent shape.