Jerky engine operation
#11
CF Monarch
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Rather than go through circuit testing on the EGR valve, I just replaced it. Well, it didn't change the problem. So I'm still looking for a solution to the problem of an engine that runs well when cold but jerks on any sort of mild acceleration after it's warmed up for more than five minutes.
#13
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I appreciate all suggestions. Yes, I can manually rev up the engine under the hood by operating the throttle body, it operates pretty normally while not under load. And it seems to idle okay most of the time, it only hesitates/runs abruptly when pulling away from a stop or accelerating while moving slowly. The irritating thing is how it is intermittent; it might go for a whole trip and operate smoothly, and the next start up a few minutes later, it will be bucking like crazy. That's why I examined, and cleaned all the electrical connections even though they looked clean and were tight.
I can't imagine that it's a compression problem, that wouldn't account for the times that it runs normally. And I did double check for vacuum leaks under the hood. I only wish the darned CEL would go on and show a code with an OBDII reader.
I can't imagine that it's a compression problem, that wouldn't account for the times that it runs normally. And I did double check for vacuum leaks under the hood. I only wish the darned CEL would go on and show a code with an OBDII reader.
#14
CF Monarch
![Default](/forum/images/icons/icon1.gif)
I appreciate all suggestions. Yes, I can manually rev up the engine under the hood by operating the throttle body, it operates pretty normally while not under load. And it seems to idle okay most of the time, it only hesitates/runs abruptly when pulling away from a stop or accelerating while moving slowly. The irritating thing is how it is intermittent; it might go for a whole trip and operate smoothly, and the next start up a few minutes later, it will be bucking like crazy. That's why I examined, and cleaned all the electrical connections even though they looked clean and were tight.
I can't imagine that it's a compression problem, that wouldn't account for the times that it runs normally. And I did double check for vacuum leaks under the hood. I only wish the darned CEL would go on and show a code with an OBDII reader.
I can't imagine that it's a compression problem, that wouldn't account for the times that it runs normally. And I did double check for vacuum leaks under the hood. I only wish the darned CEL would go on and show a code with an OBDII reader.
#15
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Still playing around with it. Thought it might be a worn wire shorting on the 7X crank sensor but that was a short lived cure; again it ran just great for one trip, then next start it ran so poorly that it actually stalled while idling. CEL light came on a few days ago...no codes with three different readers. Light went out. Another symptom - while it bucks and jerks when loading it up in drive (not moving with brakes on) it pulls strong without hesitation when doing the same thing in reverse. So I'm still thinking there's a wire shorting out somewhere with engine movement, just haven't found it yet.
#17
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I put the van on hold until the weather warmed up. Thanks to these posts https://chevroletforum.com/forum/ven...00-rpm-101149/ and https://chevroletforum.com/forum/ven...problem-29946/ I was convinced that the 24X front crank sensor was the problem. And it was, it seems. Pulling the harmonic balance was easy, and since the engine mount under there was a mass of rotted rubber I changed that out at the same time. It's running well now and took about three hours, half of which was cleaning road grime.
Thanks to all who chimed in with suggestions!
Thanks to all who chimed in with suggestions!
#19
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Rather than go through circuit testing on the EGR valve, I just replaced it. Well, it didn't change the problem. So I'm still looking for a solution to the problem of an engine that runs well when cold but jerks on any sort of mild acceleration after it's warmed up for more than five minutes.
#20
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The part you're looking for may be shown in post #5 of this thread: https://chevroletforum.com/forum/ven...plugged-97505/
Last edited by Photon440; September 27th, 2021 at 9:57 PM.
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cj7deerslayer
Silverado, Sierra & Fullsize Pick-ups
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March 7th, 2021 4:41 PM