Hey guys. My truck( 1996 f-350 w/ 5.8) has been running rough(Jolting, spitting and Sputtering at any speed) for a while now progressively getting worse with a rough idle. I have replaced a few parts such as the TPS, Plugs, Wires, Cap and Rotor, Fuel filter etc. Mostly just maintenance parts hoping that would smooth things out... well it did not so I went looking thinking and I was thinking vacuum leak so I went looking around and didnt see anything cracked or appear to be a problem. So I started the truck(Rought Idling) and I pulled the vac hose off the left side of the throttle body if standing at the front of the truck looking at the engine. When I pulled it off it smoothed out and it was running great. I could hear air sucking into the throttle body with that hose off. I took it for a spin down the street and it ran great with that hose disconnected. It leads me to believe something is clogged or not opening up.That hose leads to some time of inline solenoid with a electrical plug and then into a canister.Not sure if the canister is clogged/Bad or that solenoid is not opening. Anyone ever experience this or know where to start on fixing this issue? I guess I could replace both of those parts but I figured I would get some advice first, Thanks in Advance.

 

Have you pulled codes?

 

Hey, No I have not pulled any codes. I havent seen any check engine light nor do I have a scanner lol

 

You can have stored codes or some other issue that will trigger a code in the Key On Engine Off (KEO) tests without having a CEL



You can do it with a paper clip: How to run a Self Test

The above is a free way to check for codes. Be aware counting the flashes can be a little tedious and prone to error. It may take a few tried to retrieve the correct three digit codes. I highly suggest a cheap code reader such as the Equus 3145. It's a great investment for your toolbox.

The same link above has the code definitions. Please list any codes, by number, and when they were displayed (KOEO or stored codes aka Continuous Memory/CM). We can help decode them for you.

 

That vacuum line and the solenoid on it and the canister would not help your problem if you replace them.