5.7 chugging/ slowing down under throttle

[rzr6-4]

Hello all, I've watched from a distance for years but just now made an account as I'm having as issue I can't solve.

My 08 2500 5.7 frequently has low power/torque at low RPMs. Sometimes its so bad that when I push the gas more it actually slows down. When I push more and it downshifts it sputters, almost sounds like you are spitting water out of your mouth. Does that for a couple seconds and then takes off like it should.

The issue seems to be a little worse when it is cold (20deg F or lower) and when the fuel is low, although it does it all the time so its not a direct relationship. Seems like its not giving it enough fuel when I get on it but I'm not sure.

At first I thought it was an air issue but I tore the intake all apart and all was well, thinking fuel supply now but not sure.

 

[gt8684]

Sorry to hear about the problem, how many miles do you have on the truck? are you in need of a new set of spark plugs? I'm assuming you dont have the check engine light on, You said you checked the intake, do you have a vacuum leak? the computer can compensate for a leak but could run out of fuel if you get on it too. is it a new problem, maybe you got a bad tank of gas? when you are idle does the tach wander or is it smooth?

 

[rzr6-4]

Sorry to hear about the problem, how many miles do you have on the truck? are you in need of a new set of spark plugs? I'm assuming you dont have the check engine light on, You said you checked the intake, do you have a vacuum leak? the computer can compensate for a leak but could run out of fuel if you get on it too. is it a new problem, maybe you got a bad tank of gas? when you are idle does the tach wander or is it smooth?

Just shy of 190,000 miles, I bought it when it was a little over 160k and I haven’t done plugs but I’m sure it’s due for some. I’m fine with doing them and plan to do it once my other pick up is running but I don’t want to rush to do them right now if that’s not going to solve my immediate problem. I did have a check engine light on for the longest time that said gas cap, I replaced the gas cap, light was still there and me and a few mechanic friends were never able to figure out what the cause of the light was. Just this week it went away for the first time since I bought it, no idea why. I don’t know that I have a vacuum leak but I guess I’m not sure how to check, the PCV hose fits more or less snug on both ends but the last time I pulled it off it had some white creamy stuff in it, not sure what it was and didn’t know if I should be concerned or not. When I first bought the pick up it was off and on with this issue but lately it’s been pretty much all the time. Idles nice & smooth, runs like **** from the 1500 to 2500 range, then runs great above that again.

 

[gt8684]

You probably are due for spark plugs, its hard to say what exactly is the problem, there may not be a one simple fix for this, could be any number of things all working together to cause the problem. I'm sure you have already made sure the air filter was clean and not clogged with anything? The easiest way to check for a vacuum leak is to take a can of starting fluid and spray it around the intake, and the PCV connections anything that leads to the intake runners, and listen for the engine to change rpm when doing so, if it revs up then you have a leak where you are spraying, hence the change, just dont go to crazy. as far as the white milky in the PCV hose, its moisture mixing with the oil, usually happens when you drive only short distances, a good long drive will usually burn all of that off.