Jimmy Brideau

my 1994 Chevy with a 4.3 5 speed manual works perfect when the power to the SPEED BUFFER is disconnected...when power is connected to speedo my truck has a shudder when shifting gears and at cruising speed or just off idle...but works fine when on the throttle...I have changed everything you could think of and still same...I have not driven it in the last year because I haven't had time...I am going to try swapping the PCM next....I hope it works but if not I will just run it without speedo until I can figure it out...I have inspected wires but I may change the harness if the PCM swap fails

CraigD98

Had new crate 5.7L and new transmission installed and now this problem. They thought it was happening when shifting but its actually not during shifting. I can be cruising at, for example, 50 mph for several minutes and all the sudden it "bucks" or what feels like a hard shift. No RPM drop or anything. Just a buck. they couldn't figure it out after checking everything possible and even sent back the transmission to manufacturer and got a new one because they thought they received a bad transmission. But that wasn't it. It did NOT do this before the new motor and transmission. So I am at a loss. I took the truck because they exhausted all possibilities and it otherwise runs fine; but I have 6 months left on my year warranty and am contemplating taking it back just telling them it is getting worse, so figure it out. BUT, I don't think they can. Otherwise I might take it somewhere else for some fresh eyes. Thoughts??

CraigD98

Had new crate 5.7L and new transmission installed and now this problem. They thought it was happening when shifting but its actually not during shifting. I can be cruising at, for example, 50 mph for several minutes and all the sudden it "bucks" or what feels like a hard shift. No RPM drop or anything. Just a buck. they couldn't figure it out after checking everything possible and even sent back the transmission to manufacturer and got a new one because they thought they received a bad transmission. But that wasn't it. It did NOT do this before the new motor and transmission. So I am at a loss. I took the truck because they exhausted all possibilities and it otherwise runs fine; but I have 6 months left on my year warranty and am contemplating taking it back just telling them it is getting worse, so figure it out. BUT, I don't think they can. Otherwise I might take it somewhere else for some fresh eyes. Thoughts??

jonathanl

This thread has been running for quite some time. I’ve got a ‘94 suburban doing the exact same thing now. Has anyone actually found a solution for this bucking at cruise issue? Like to hear your fix.

Kevmore007

I seem to have developed the same problem. Little single miss at part throttle. Sometimes a few in a row.