The Stupid Engine Questions Thread

[TD Henley]

Its almost like power gets cut off to the motor. But it stops when the rpms get low. Theres a big diffrence between just letting off tge gas a when it does this

 

[AK49BWL]

That is called DFCO, or Deceleration Fuel Cut-Off - essentially works similar to an engine brake, but what it actually does is retards timing down to -5 degrees while supplying the engine with minimal fuel. It's something you can mess with in the PCM tune.. Great for coasting to a stop, and uses a lot less fuel than if it weren't in effect. Perfectly normal tho

 

[Viru]

Could just be natural behavior of the motor causing deceleration when the torque converter is locked up, unless you were pointing at something else

 

[Jcauli82]

Okay this is crazy just started happening this evening my truck is sputtering and dying when it has low rpms while I'm driving it. Seems to be doing ok when I accelerate and get it past 30 mph.... But when im braking at a stop light or whatever , the gas pedal is moving on it's own trying to accelerate. Any ideas anybody? 98 k1500 5.7l

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[TD Henley]

That is called DFCO, or Deceleration Fuel Cut-Off - essentially works similar to an engine brake, but what it actually does is retards timing down to -5 degrees while supplying the engine with minimal fuel. It's something you can mess with in the PCM tune.. Great for coasting to a stop, and uses a lot less fuel than if it weren't in effect. Perfectly normal tho

thanks man. Do you think theres a way to controll it better? Like on a toggle switch or something?

 

[Wade]

Okay this is crazy just started happening this evening my truck is sputtering and dying when it has low rpms while I'm driving it. Seems to be doing ok when I accelerate and get it past 30 mph.... But when im braking at a stop light or whatever , the gas pedal is moving on it's own trying to accelerate. Any ideas anybody? 98 k1500 5.7l

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Sounds like two separate problems; sputtering and dying and the gas pedal depressing on it's own, is it?

 

[Jcauli82]

I just disconnected the cruise control earlier so I'm not getting the gas pedal sticking symptom anymore but I was going up a hill shortly after that and I got the sputtering so that's where I'm at with it right now

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[flat landah]

Hey guys, new here hoping to get pointed in the right direction. I have a 94' k1500 with 100k on the dash. Months ago I had a couple of very minor misfires and sputtering while on the road, nothing major. Well, I just completed a cross country trip in the truck and the misfire came back with a vengeance. Got to the point where it was almost undriveable. It misfired so bad it blew open my muffler. I got it home, replaced the MAP sensor, coolant temp sensor, timing chain (which did have quite a bit of slack in it), new distributor, cap rotor and module, fuel sending unit and fuel filter. STILL misfires.... The only thing I can think of now is a burnt valve maybe? The truck idles beautifully, once I put it under a load (if i have it in 3rd or 4th and whack it) it misfires/pops, sputters.

Haven't checked compression yet, that is my next step but... for the love of god is there anyone with a suggestion out there?

 

[Viru]

Hey guys, new here hoping to get pointed in the right direction. I have a 94' k1500 with 100k on the dash. Months ago I had a couple of very minor misfires and sputtering while on the road, nothing major. Well, I just completed a cross country trip in the truck and the misfire came back with a vengeance. Got to the point where it was almost undriveable. It misfired so bad it blew open my muffler. I got it home, replaced the MAP sensor, coolant temp sensor, timing chain (which did have quite a bit of slack in it), new distributor, cap rotor and module, fuel sending unit and fuel filter. STILL misfires.... The only thing I can think of now is a burnt valve maybe? The truck idles beautifully, once I put it under a load (if i have it in 3rd or 4th and whack it) it misfires/pops, sputters.

Haven't checked compression yet, that is my next step but... for the love of god is there anyone with a suggestion out there?

Have you checked the ignition coil and spark plugs yet?

 

[munrom77]

Hey guys, new here hoping to get pointed in the right direction. I have a 94' k1500 with 100k on the dash. Months ago I had a couple of very minor misfires and sputtering while on the road, nothing major. Well, I just completed a cross country trip in the truck and the misfire came back with a vengeance. Got to the point where it was almost undriveable. It misfired so bad it blew open my muffler. I got it home, replaced the MAP sensor, coolant temp sensor, timing chain (which did have quite a bit of slack in it), new distributor, cap rotor and module, fuel sending unit and fuel filter. STILL misfires.... The only thing I can think of now is a burnt valve maybe? The truck idles beautifully, once I put it under a load (if i have it in 3rd or 4th and whack it) it misfires/pops, sputters.

Haven't checked compression yet, that is my next step but... for the love of god is there anyone with a suggestion out there?

Sounds like compression/burnt valve issues


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