Help a newb please

[billybobby]

A little history first I have had five shops look at my truck and charge me money and through parts at it. My truck has 5.3 whipple charger 42LB injectors, Walbro intank pump high output, tholy headers no cats 3'' exhaust and nelson tune. I have had poor AllenTalk to three of these Utarded Mechanic's. Allen has been nice enough two send out two PCM'S of course and listen to my struggle over the last few month's. Any help or idea's would be great. First off the truck runs fine at low RPM if you get into the throttle it acts like it is starved for fuel and falls on it's face if you slowly get into it it runs better. It also runs much better when cold. The first shop told me I needed a new fuel pump, installed a Walbro high flow pump. With the fuel pressure at 60 psi Wot and foot on the brake the truck fell on it's face for a quarter of a mile still like it was starved for fuel. With a snap on Modis it showed not one misfire in live data and no codes. A computer later I gave up on those guys. Next shop has a tech 2 scan tool. No codes they said they even disconnected 2 plug wires and let it run for 15 minutes still no codes and no misfires in live data. They have some exhaust sniffer tool and said it is rich at when it is poping. Still had one of the PCM'S so they put that in there again no change. I skipped a few mechanics but this last one taught at a college and seems to know the most. He has still had my truck for 3 weeks and run dozens of tests. Same result. I have note's on all the shizz I have been through on this if anybody needs more info. Thanks in advance

[DamnYankee]

Does it have a Ford or Doge emblem anywhere on the body?



Sorry, couldn't resist. Hope you get it figured out.

[RedHeartbeat]

They are checking the fuel pressure while driving at wide open throttle and the fuel pressure is 60 PSI? What are the spark plugs gapped at? They should be no more than .030" with a blower. How much HP do you suppose the engine is capable of producing? The Walbro is pretty much limited to a max of 550 hp in optimal settings. Fuel pressure is definitely what I'd be monitoring the closest during these issues.

[ff_jeff]

its probably somthing stupid like maf sensor or iat or somthing dumb like that. Mybe try a stock pcm or take blower off and inspect for damage? Its weird that the engine didnt throw a code though. Stupid question but u using 93octane and how much boost, maybe too much.

[sanger rat]

What are the spark plugs gapped at? They should be no more than .030" with a blower.

??? Can you enlighten me. Why only .030?

[GMCwantsLS1]

Like Red said check the plugs. The stockers won't work well as you will need the TR6 plugs. Strange no misfires. Maybe a bad knock sensor, TPS or MAF?

[billybobby]

Does it have a Ford or Doge emblem anywhere on the body?



Sorry, couldn't resist. Hope you get it figured out.

Ouch
you didn't have to be so hurtful.

The plugs are TR6's gapped to what Allen told me. Mass air is reading normal knock as well and the fuel pressure was tested while driving. The truck by coach Nelson is well under 550 horse. I run 91 octane which is what it was tuned for. It did run great with his mods for about 2 month's. I am really at a loss and I have taken it the supposed best Mechanics in St. George, UT I might run it to Vegas.

[RedHeartbeat]

Borrow a known good crank and cam sensor and swap them out. They may be losing their sensitivity/accuracy.

On a side note, have the PCM grounds checked at the head. You would not be the first person to have bad grounds from the PCM to the driver side cylinder head.

[SCIV]

On a side note, have the PCM grounds checked at the head. You would not be the first person to have bad grounds from the PCM to the driver side cylinder head.

Side thought...belt slip at high RPM?

[ff_jeff]

Side thought...belt slip at high RPM?

this would make allot more sense. Maybe its to loose or tight. post vid, I bet we can all figure this one out together. or not lol
but it seems like the pcm might have learned wrong or somthing. Just a theory but lets say you get a nelson tune, and somthing is wrong but not noticeable. like a sensor that is reading incorrectly. Wouldent that make the relearn mess up because it had currupted data? truck relearns but with the pretence that all is well. does this make sence guys? Maybe a stock pcm would unmask the problem, if its not a stated problem. Or I could be full of it.