I have a 1998 Ram 2500 5.9 V8 FI

I had the CEL come on about a week ago, got it checked and it said that cylinders 2 & 3 were missing. It was idleing rough but drove fine. I replaced the sparkplugs, made no noticeable difference. Then moved on to the cap and rotor. Made a difference, noticed the idle was better. It was still missing though. So I moved on to the ignition coil, helped but still nothing...and finally changed the wires...almost back to normal but still misses and idles rough. The thing that I noticed was that the Purge Solenoid wasnt connected when I bought it and when it ran fine. But when I plug the vacuum onto it, it makes the idle rough and when I unplug the vacuum it idles better. Any ideas? only about 120xxx miles...

 

make sure the purge solenoid is not upside down. There is an arrow on it. I made that mistake.

Also, check all the injector connectors. if they are loose you will get a missfire in that cylinder.

Or you can get a purge solenoid from the junkyard.

 

I think the solenoid might be bad, but if you go up on the passenger fender towards the head lights. their is a bunch of plugs/connectors. One goes onto thr frame under the radiator and all the others go nowhere. ill put pics up sometime when its not 110 degrees

 

There's a way to check it by feel and sound. IF it was installed backwards, the PCM will need to be reset 100% otherwise, even when flipping it around, the CEL will come on and it will start to run rough again- been there and done that after SOMEONE ELSE flipped it on me years back before I began doing all the work myself.

Once you've got it all plugged back in- connect the bat. NOTE: make sure that all lights and doors and radios are off before doing so. This reduces the chance of a voltage spike / arc condition from happening thus risk of taking out the PCM.

Start the vehicle. Place your hand around the solenoid- feel for clicking. Alternative method: using a long handle prybar, place one end on the solenoid and the handle up to your ear- listen for clicking.

ON both tests- if it's clicking- it's working. However, the solenoid, though mechanically moving, may not be the root cause but rather, either a spent diaphragm or spent canister BOTH of which will throw an OBD code and the idiot light will illuminate.

If so, R & R both and check for a dry-rot condition at the PURGE canister inlet. Very common failure. Check all lines for leaks too.

CM

 

why did this get moved to general?