I have a 2001 Ram 1500 with a 5.2. My Malfunction Indicator Light has come on and off a couple times over that past 2 weeks. I took it to the local dealer and they did a Diag and it showed that cylinder 4 is missfiring. They replaced the plug wires (I replaced the plugs 2 months ago), distributor cap, rotor, the cylinder 4 injector and reset and tested the system and cylinder 4 is still missfiring. They did a compression test and it was OK. They also removed and inspected the intake and it was OK. They talked to the support people at Dodge and have come up with nothing, they don't know what's wrong. They did not charge me for any of this which makes me wonder why? (Red Flag)! Now they want to pull the Head to check the piston, valves, gaskets and the head itself which will cost me $800 just to pull the head. Does anyone have any suggestions on what might be causing this?? Please HELP!!!

 

Could be a flat spot on the cam, burnt valve, or a stuck valve. Pulling the head may be the best option right now.

 

Wouldn't the compression test show if there was a problem with any of the parts mentioned? Yes ... MAJOR red flag.

Has anyone bothered to check the wiring to the injector? That's just ONE additional item to look at before yanking the head.

 

Faulty pcm?

 

I dont know but my #4 misfiring was caused by a clogged injector. check that. vwanddodge is good at injectors, I think his test was unplug number 4s injector and see if there is a change in idle, if not then there is your problem, if it does change then it is deeper than that. hope ths helps.


BNB

 

i have a 98 1500 5.9, and my #5 was misfiring. i checked the wires, changed the plugs, and cleaned the injectors. it worked for about a week, then it came back. i cleaned the fuel rail, and it was pretty gunked up. i would check the fuel rail.

 

There have been past posts where the 'Crankshaft Position Sensor' was going bad and caused a hard to diagnose miss fire problem.

I would also double check that the ignition wires are placed according to this TSB

http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

 

Yes, that is the test. I also recommend unlugging the injector and checking the resistance of the injector. Chances are the fuel rail is dirty; however, I would be hard-pressed to believe that only #4 is clogged.

 

I took it to another shop for a second opinion. They checked the fuel rail, the fly wheel, injector wiring, everything they could think of and can not find anything external. They also pulled the valve covers and checked the cam and everything looked good. They did discover that it only misfires at idle. Once the RPM's get up the misfire goes away. They also checked the compression and cylinder 4 has the best compression of all of the cylinders. I say screw it and I am going to drive it until it starts misfiring under driving conditions.