engine stumbles upon acceleration

[jbryant]

i have a 1998 z71 4x4 with the 5.7 vortec engine. i have two problems that have began happening after the truck was wrecked.

1) upon initial acceleration the truck stumbles, sometimes even dies when taking off. codes say that there is a vacuum problem. the evap hose from the charcoal canister to the solenoid on the throttle body was cracked; could not order factory replacement so i fabricated one from fuel hose. the problem still persists after i repaired this hose. the hose is thick enough that it should not be collapsing. i have swapped MAF out with a known good one from my uncles truck; cleaned the throttle body; looked for other vacuum lines that could be the problem but can't find anything.

2) transmission doesn't want to shift between 2nd and 3rd. I get up to about 55 MPH and the RPMs sky rocket before it shifts. Please Help! I am at the end of my rope. truck ran perfect before wreck. took it to the frame shop, a week later started having these problems.

[2000CAYukon]

You should post the codes. A smoke test might need to be performed to find the source of the vacuum leak.

How is the tranny fluid after the wreck? If the truck will not shift into 3rd and revs like it is neutral, is not good. Could be the 3/4 clutch pack.

//2000CAYukon

[jbryant]

Thanks for the reply. The code that I'm getting is P0102. As for the tranny, the fluid is fine. Just the right amount, doesn't smell burnt, and there doesn't seem to be any sign of metallic flakes or anything like that. May be this additional info will help. Thanks again.

[j cAT]

Originally Posted by jbryant

Thanks for the reply. The code that I'm getting is P0102. As for the tranny, the fluid is fine. Just the right amount, doesn't smell burnt, and there doesn't seem to be any sign of metallic flakes or anything like that. May be this additional info will help. Thanks again.

on the transmission get the drive train codes..this is a oem specific code...

with the 102 code this most always the engine has a vacuum leak / air bypassing the maf sensor.............


check the pcv/hoses/crankcase/valvecover rubber hose seals.. the air ducting down stream of the maf for leaks poor seal..

even the oil dip stick can case this if not seated..

[jbryant]

Thanks for the replies. Found the problem, it was the ENG-I fuse under the hood. Can't believe it! Still having problems with the transmission.

[daarrve]

Originally Posted by 2000CAYukon

You should post the codes. A smoke test might need to be performed to find the source of the vacuum leak.

How is the tranny fluid after the wreck? If the truck will not shift into 3rd and revs like it is neutral, is not good. Could be the 3/4 clutch pack.

//2000CAYukon

Can you please tell me what is a smoke test and how do you do it?

[2000CAYukon]

Originally Posted by daarrve

Can you please tell me what is a smoke test and how do you do it?

Sure. Take a look at this link http://www.aa1car.com/library/vacleak.htm and look for the section "USING SMOKE TO FIND ENGINE VACUUM LEAKS"

//2000CAYukon

[daarrve]

Originally Posted by 2000CAYukon

Sure. Take a look at this link http://www.aa1car.com/library/vacleak.htm and look for the section "USING SMOKE TO FIND ENGINE VACUUM LEAKS"

//2000CAYukon

Thank you.