Hi guys,

I'm a new member, just purchased 96 Ram 1500 with 5.9, engine light is on runs a little rough at idle most of the time, sometimes it idles pretty smooth. Did a diagnostic at Pep Boys and it showed a code that said misfire cylinder #2. We had the "Master tech " diagnose the problem and he said he though it was a valve not opening or closing correctly. The truck runs great under acceleration and idles pretty smooth sometimes and much rougher at others. Please give me your thoughts??

Thanks!

 

You should do a compression test. How old are the plug wires? Try routing them according to this TSB. http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

 

Thanks zman, I have new plugs, wires and cap routed per the tsb. As I mentioned it runs a little rough sometimes and smoother at others but accelerates and drives just fine. I'm not familiar with valve issues or symptoms so I'm wondering if anyone else has experienced anything similar?

 

Pretty much everyone here has had that problem at one time or another. lol Do the compression test first. Make sure the plug is on the injector properly. Get some Techron +, maybe dirty injector. Also read the Plenum thread/sticky on top of the page.

 

Thanks again zman, I have used seafoam on 1 tank, Lucas on the 2nd and not much of a change in the rough idle. I just hope it's not a valve issue

 

Pull the sparkplug and see what it looks like too.

 

The plugs look good and dry, no oil residue. When I changed the plugs they all looked the same kind of tan color not black with carbon.

 

Swap the 2 and 4 injectors. See if the problem migrates.

 

Ok I had the fuel injection system cleaned at the local shop, still runs the same...sometimes smooth and sometimes rough at idle. p0302 and p0300 misfire cylinder 2 and multiple misfires
I double checked plug wires per tsb cleared the codes and ran it on the highway for a little over an hour to let the monitors reset. When I got off the freeway it idled smooth at a few of the stop lights. It runs like a dream past idle, no codes popped and the idle was much smoother. I started it up to move it out of the driveway and it was running rough again popped the p0302. I have saw a lot of chatter on the plenum gasket I'm wondering if that could be the cause of this can of worms??

FYI I rented a compression tester from the parts house it it was junk, it leaked and I couldn't get accurate readings from any of the cylinders. I will have to get another one after the holiday. HELP!!!

 

Yes, the plenum can be the cause, the cat may be getting clogged.