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01 silverado 3500hd 8.1 studder/low power

treehugginhippi

By treehugginhippi
in Ask A GM Technician

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treehugginhippi New Member

treehugginhippi

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Hi, this is my first post on here but I have done a search and have gone through many steps to correct the problem before I made my account.

 

So here we go the truck is a 2001 Silverado 3500hd 8.1l 5spd cab and chassis.

It seems to have 3 dead holes for no apparent reason.

 

A bit of back story. I am the mechanic for a plumbing company in Kansas City, we have 32 04-12 Chevy express 3500 6.0, 6 04-06 Silverado 3500, and 3 of these 8.1turds 2 of which run perfect and this one.

 

Symptoms:

runs rough has a bad studder/miss low power and it takes full throttle to keep it going 70mph.

 

What I have done:

As I said I have read through lots of your previous posts and have exhausted all of my knowledge and patience.

I have replaced/swapped parts from our other trucks... Those parts are,

throttle body

egr valve

map sensor

maf sensor

evap purge sol

ckp sensor

Exhaust/to rule out cats

all 8 spark plugs

all plug wires

Fuel rail

fuel pressure regulator

all 8 injectors

 

I also tested fuel pressure... With my scanner running the pump constant it sits at 55-57psi at idle it sits at 46-48psi and spikes back to 55ish with full throttle.

 

Tested coil resistance and all 8 are within spec. Also put a spark tester in and all 8 have same looking spark

 

ran a compression test:

1) 160

2) 158

3) 160

4) 160

5) 165

6) 165

7) 165

8) 170

 

this truck of the three we have had the lowest mileage @195k and also has the best care/driver.

 

With my scanner I shut off injectors one at a time, all changed engine tone and made the studder worse except number 2,4,7 which didnt sem to change anything. Injector test was done at 1500rpm.

 

Any help would be greatly appreciated.

treehugginhippi New Member

treehugginhippi

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Posted

I forgot to mention, no cel or service engine soon light. It was on for o2 sensors, and ckp sensor but I cleared the codes after replacing the ckp sensor. Also this truck does not have downstream o2 sensors yet the exhaust is all factory.

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