Bucking when cold
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Lead Driver
Joined: Oct 2010
Posts: 5,126
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From: Columbus, Oh
Bucking when cold
My truck did this last winter, but not really noticeable, now it seems like its getting worse, or it could be that the weather is just getting worse again.
When she is driven when cold, it has a slight buck or hesitation at low RPM's. This goes away when you get into the throttle or warms up and runs like a dream. I'm thinking maybe its not getting enough fuel/oil psi when cold? GPR, GP's all volt/ohm tested good and it fires right up in the morning. Fuel pressure is 63 PSI @ idle. HPOP is full. Fresh Rotella Syn oil. Fuel filter and FPR screen done this summer. No CEL.
I'm sure it could use injector O rings, but would they make this happen? HPOP going out? I don't have a way to test HPOP pressure unless my buddies snap on gauge can read it or does this have to be done with a manual gauge?
Sorry for the novel, but any input is appreciated
When she is driven when cold, it has a slight buck or hesitation at low RPM's. This goes away when you get into the throttle or warms up and runs like a dream. I'm thinking maybe its not getting enough fuel/oil psi when cold? GPR, GP's all volt/ohm tested good and it fires right up in the morning. Fuel pressure is 63 PSI @ idle. HPOP is full. Fresh Rotella Syn oil. Fuel filter and FPR screen done this summer. No CEL.
I'm sure it could use injector O rings, but would they make this happen? HPOP going out? I don't have a way to test HPOP pressure unless my buddies snap on gauge can read it or does this have to be done with a manual gauge?
Sorry for the novel, but any input is appreciated
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Lead Driver
Joined: Oct 2010
Posts: 5,126
Likes: 44
From: Columbus, Oh
No, EBPV has been unplugged for a while
Posting Guru
Joined: Aug 2007
Posts: 1,601
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From: Cato Arkansas
Tried a different cam sensor thats h
Just a out of no where guess but good to always have extra anyway
Just a out of no where guess but good to always have extra anyway
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Lead Driver
Joined: Oct 2010
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From: Columbus, Oh
I doubt it's the CPS, but you never know...nobody heard of anything like this?
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Hotshot
Joined: Jun 2007
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From: Austin, TX
To be clear on whether it's the same symptom... Does it feel like the engine is "jumpy" and the truck starts jerking back and forth until you either try to accelerate more or let off the accelerator? That's what mine is doing. Starts fine cold, runs fine with that exception... I have to wonder if mine is b/c my IAT sensor is gone. In warmer weather it doesn't do it, but now that it's cooling down here, I noticed the truck started doing it again. Did it all last winter, stopped all summer, now starting again with cooler weather.
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Lead Driver
Joined: Oct 2010
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From: Columbus, Oh
My truck is doing it. It does it until it gets to about 160-165*. I can't figure out why it does it, but it's only in certain situations. Like going uphill between 1300-1700 RPM. When it does it, I notice ICP fluctuates a few hundred PSI. My IPR is good, o-rings are good, ICP is new, wiring is good, etc. Not sure what's causing mine.
To be clear on whether it's the same symptom... Does it feel like the engine is "jumpy" and the truck starts jerking back and forth until you either try to accelerate more or let off the accelerator? That's what mine is doing. Starts fine cold, runs fine with that exception... I have to wonder if mine is b/c my IAT sensor is gone. In warmer weather it doesn't do it, but now that it's cooling down here, I noticed the truck started doing it again. Did it all last winter, stopped all summer, now starting again with cooler weather.
To be clear on whether it's the same symptom... Does it feel like the engine is "jumpy" and the truck starts jerking back and forth until you either try to accelerate more or let off the accelerator? That's what mine is doing. Starts fine cold, runs fine with that exception... I have to wonder if mine is b/c my IAT sensor is gone. In warmer weather it doesn't do it, but now that it's cooling down here, I noticed the truck started doing it again. Did it all last winter, stopped all summer, now starting again with cooler weather.
Postmaster
Joined: Sep 2007
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From: Medford Oregon
Travis, why is your IAT sensor gone .. where did it go?
As far as a slight bucking, hard to describe, when out on the freeway I must say I did notice something this winter almost like a spark plug misfiring now and then, but only when cruising. Thought it was just bumps in the road but maybe not.
Next week I'll monitor ICP - IPR when going to work and see if any funny numbers pop up.
As far as a slight bucking, hard to describe, when out on the freeway I must say I did notice something this winter almost like a spark plug misfiring now and then, but only when cruising. Thought it was just bumps in the road but maybe not.
Next week I'll monitor ICP - IPR when going to work and see if any funny numbers pop up.
Hotshot
Joined: Jun 2007
Posts: 10,008
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From: Austin, TX
I'm not sure where my IAT sensor went, but it's MIA. LOL It was there when I did the 6637 4 or 5 years ago, but it's gone now. The IAT display on the scan gauge reads a constant like 50* or something whether it's 110* or 15* outside. Not sure how the IAT might effect the running of the engine while cold, but IIRC it does have some effect on fueling when it's cold.
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Lead Driver
Joined: Oct 2010
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From: Columbus, Oh
I guess I will have to figure out a way to put it on the 6637 considering Travis and I are having the same problems and the only common denominator is the missing IAT.