bucking from dead stop
Woodster
11-15-2003, 09:56 AM
Hi All,
I have a 1994 Chev C-1500 with the 4.3L engine and only 23,000 actual miles on it. Most of my driving is around town and short hops. Many times the engine doesn't heat up to operating temp.
My problem, yesterday, was taking off from a dead stop my truck bucks like everything until I reach 20 MPH then it's fine. Starts good and sounds good in neutral, but like I say, under load it bucks like mad until 20. The problem is intermittent, but yesterday, it was exceptionally bad. I had the wires, plugs, rotor and cap replaced along with the 02 sensor not too long ago.
I had my mechanic put it on the diagnostic computer to see if he could find any faults. None. The "check engine" light doesn't come on when my truck is bucking. He's stymied and I afraid to take it out of town.
Any suggestions?
Woodster
I have a 1994 Chev C-1500 with the 4.3L engine and only 23,000 actual miles on it. Most of my driving is around town and short hops. Many times the engine doesn't heat up to operating temp.
My problem, yesterday, was taking off from a dead stop my truck bucks like everything until I reach 20 MPH then it's fine. Starts good and sounds good in neutral, but like I say, under load it bucks like mad until 20. The problem is intermittent, but yesterday, it was exceptionally bad. I had the wires, plugs, rotor and cap replaced along with the 02 sensor not too long ago.
I had my mechanic put it on the diagnostic computer to see if he could find any faults. None. The "check engine" light doesn't come on when my truck is bucking. He's stymied and I afraid to take it out of town.
Any suggestions?
Woodster
GMMerlin
11-15-2003, 10:36 AM
It sounds like you have developed a misfire condition.
I would have the ignition system tested first.
I would have the ignition system tested first.
oldbluecelica
11-15-2003, 06:57 PM
automatic or manuel?
suonds like a dirvetriane issue if it stops at 20. is that when it shifts?
suonds like a dirvetriane issue if it stops at 20. is that when it shifts?
Woodster
11-16-2003, 05:22 PM
Hi Oldblue,
The bucking stops at 20 M.P.H. and the transmission is a 3 speed automatic with overdrive. At 20, I should be in at least 2nd by then. Strange as it may seem, it doesn't buck in reverse. Drivetrain? Sounds plausable. With my truck in neutral, no bucking. Only when under power and I try to move.
I checked in with my mechanic. He disconected the EGR vacuum hose and told me to run it for a few days to see if anything happens. I haven't tried it out as yet.
Many thanks for your reply,
Woodster
The bucking stops at 20 M.P.H. and the transmission is a 3 speed automatic with overdrive. At 20, I should be in at least 2nd by then. Strange as it may seem, it doesn't buck in reverse. Drivetrain? Sounds plausable. With my truck in neutral, no bucking. Only when under power and I try to move.
I checked in with my mechanic. He disconected the EGR vacuum hose and told me to run it for a few days to see if anything happens. I haven't tried it out as yet.
Many thanks for your reply,
Woodster
RABarrett
11-18-2003, 01:20 PM
I also suspect ignition related problems. Having the engine 'scoped would reveal many things. In today's methods of doing things, the computer is blamed before gathering the facts. Now as in past times, the ignition will cause more than 90% of your problems. It is possible for one of your new parts to have a problem, likely the wires. Ray
Jimmy Eaddy
11-19-2003, 10:00 AM
Have you replaced the fuel filter? It might not be getting enough fuel.
Jimmy Eaddy
11-19-2003, 11:09 AM
Have you replaced the fuel filter? It might not be getting enough fuel. ! I had the same problem with my 95 chev 4.3. I replaced the fuel filter under bed. It fixed mine. Give it a try! Alot less expensive!
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