LMM throwing p0090

[DIESELMAFIAPER.LB7]

i have a friend I did a dpf/egr delete on his truck and did a tune and all was well drove it around few hours then it threw the p0090 on his number 5 tune when he mashed it and wouldn't clear and was idling around 1500-1600 psi? thought that maybe the fprv popped and wouldn't reset... I cleared the codes and let it sit off for a few min started it and took it for drive floored it few times drove it around for bout 15 mins nothing ran great

so he loads up heads home to Montana and gets to the Idaho/montana border and throws the code again and wont clear again and keeps flashing reduced engine power on and off for a few mins then is fine for 10-15 miles does it again.????? rail isn't changing with it boost isn't changing slight power loss but he put down to the stock setting for now.

I have the june 21st update from efi live is this just a freak thing and a bad regulator or a loose ecm connection from the dsp 5 swith I put in? usually these things cause rail to go up not down? I didn't undue the regulator harness at all either?

anyone around the Missoula area with a v2 that could watch the milla amps to the reg?

 

[DIESELMAFIAPER.LB7]

I'm thinking it's a harness issue did some searching and found by the ecm I disturbed some people have had chaffing issues with this code. I didn't notice any but wasn't looking either

he stopped and I had him wiggling harness's around as I thought that might be a issue got nothing so I had him unplug the reg harness and he said rail didn't change stayed at 12k plugged in or not has to a be reg then

 

[DIESELMAFIAPER.LB7]

So I have this truck back new fpr didn't change anything flashed to stock didn't change anything I'm getting 12v from the ecm at the fpr harness when I turn the key on. Pig tail off the fpr is good as well

Soon as the truck starts it's a sitting at 12.5k rail and doesn't change much it spikes 28k cranking but then goes to 12k I unplug the fpr nothing changes still could this be a bad ecm? Or a plugged return line somewhere? currently looking for wires that are loose or messed up but nothing yet.

 

[DIESELMAFIAPER.LB7]

It just baffles me it stuck at 12k rail and unplugging the regulator doesn't change anything....

Anyone have any other ideas

 

[DIESELMAFIAPER.LB7]

Well swapped a race plug in to see if the rail was already maxed out and it was soon as the truck starts it stays at 28k rail so did the ecm take at shit?

I tested via gms procedure terminal 2 has no power with key off like it's supposed to be and terminal 3 has power with key on kicks off like it's supposed to when ecm powers down? Wires test fine obviously



On edit I just pulled his regulator and put it on my top cp3 works perfectly idled great drove fine so I've ruled out the fprv, the regulator, wiring is good to bale connectors, currently checking wires from bale to ecm

 

[DIESELMAFIAPER.LB7]

http://www.duramaxdiesels.com/forum/showthread.php?t=33530

Been reading this none of the damn links work but were is terminal x1-76? says if the fuse power there is blown this dtc will set.

other then that im stumped for tonight truck had a bully dog I un downloaded before reading the stock file out. perhaps a gm full flash will help something?

 

[DIESELMAFIAPER.LB7]

Really no one on this forum has a word to say..........................

 

[IOWA LLY]

Sounds like maybe a rail pressure sensor issue.

Sent from my SCH-I535 using Tapatalk 2

 

[DIESELMAFIAPER.LB7]

Sounds like maybe a rail pressure sensor issue.

Sent from my SCH-I535 using Tapatalk 2

I believe I have a spare one, why would it throw a regulator code for a bad rail pressure sensor? Guess I'll see if the spare I have is good

 

[Bonestock]

I wonder if you have an injector or two returning alot of fuel? Also by unplugging cp3 an fuel psi not maxxing out it makes you wonder about the cp3?

 

[DIESELMAFIAPER.LB7]

No its maxed out, the reason it sat at 12k is the fprv was blown open right away. I plugged it now rail is at 28k whether the regulator is plugged in or not. Swapped the sensor no change at all so back to unhook in the ecm and bale connectors

 

[IOWA LLY]

Have you tried re-flashing the ECM?

 

[DIESELMAFIAPER.LB7]

Have you tried re-flashing the ECM?

Yes i put his stock tune back in no change, haven't tried a dealer re flash yet closest dealer is 30 miles away but I may try it

 

[DIESELMAFIAPER.LB7]

Well its a ecm or bad connection in the connector to the ecm if you plug the ecm in tight it throws all sorts of codes leave just a smidgen loose nothing can drive down dirt roads ect ect bumps don't affect It?

Cousins a gm tech and he seems sold on the ecm I'm not totally sure if I wiggle all the wires with it not completely in nothing happens. If i plug it in and giggle wires truck goes nuts and/or dies

 

[Bonestock]

Go thru the pin outs with snap on tool and tighten them up. I had this happen on my old lb7. we actually zipped tied the bale connector tight and the problem went away. I think you could tighten the metallic connectors with the snap on terminal tool. May be a pain in the ass but you most likely have it nailed. If it were the ecm the jiggling wires thing most likely would not come into play.

 

[DIESELMAFIAPER.LB7]

Unless there's a weak solder joint in the ecm cause we are making the ecm flex when we move the connector around And we went threw the pin outs nothing bad so it's at gm now waiting for a warranty approval of a ecm

 

[Bonestock]

Have you tested with an ohm meter between bale connectors and ecm harness and then wiggle wiring?