Acts Like A Timming Problem

[dcmargush]

I have a 99 2500 Sliverado w/ 6.0L.....

 

I have a studder or back fire out the intake, or miss or something between 1500-2000 RPM under load. I have search the forum here and found the ref to the torque conv. going bad, and I am hoping it is not the issue as it is only 2 years old.

 

The problem goes away after 2k RPM, so if it is a t.c. I don't know where the "lock up" is, but it is very similar to a problem I had on my 84 w/ HEI dist. that was breaking up or out of time under load, and I had to rebuild the dist and replace the small coil in the dist.

 

This engine (LS1 derivative) has the individual coil packs. the problem doesn't throw any/enough codes to set off the message center, so I am hunting in the dark.

 

Any suggestions on testing the cam / crank position sensors, or anywhere else to look?

[bobcat5544]

I have a 99 2500 Sliverado w/ 6.0L.....

 

I have a studder or back fire out the intake, or miss or something between 1500-2000 RPM under load. I have search the forum here and found the ref to the torque conv. going bad, and I am hoping it is not the issue as it is only 2 years old.

 

The problem goes away after 2k RPM, so if it is a t.c. I don't know where the "lock up" is, but it is very similar to a problem I had on my 84 w/ HEI dist. that was breaking up or out of time under load, and I had to rebuild the dist and replace the small coil in the dist.

 

This engine (LS1 derivative) has the individual coil packs. the problem doesn't throw any/enough codes to set off the message center, so I am hunting in the dark.

 

Any suggestions on testing the cam / crank position sensors, or anywhere else to look?

 

Do this first. If you have a propane torch or starter fluid...start the engine let it idle...with the propane torch turn the valve on (DO NOT LIGHT IT). Run the nozzle around the intake manifold and hoses or with the Starter fluid spray around the Intake Manifold and Hoses...If the engine revs up then you have a vacuum leak.

(Note don't get to close to the throttle body. Throttle body may suck it in and cause it to rev up.)