Hi I have a 2002 Ram 1500 quad cab 4x4 with a 5.9L gas engine with 133,000 miles on it. The problem started with a check engine light. I currently have it a local repair shop and they are having a tuff time getting to the heart of the problem. It started with a #5 cylinder misfire, just when they think they have the answer a different cylinder comes up with the same problem. They thought they found the problem when they found a shorted wire on a O2 sensor, but no luck. They plugs, wires, cap and rotor have all been replaced. Have any of you had a similar problem and if so what was your answer to the problem. Thanks.

 

Hey, welcome to the forum. Normally I am in the 2nd Gen forum, as I have a 97 RAM with the 5.9, but I have had your exact problems.

When it was in the process of setting that check engine light, did you notice any power loss? Like it would only rev to 3000 RPM maybe? Mine had about 185k on it when it did the same thing, #5 misfire, then it went to multiple cylinder misfires, etc.

Long story short, it could be a few different things, but maybe this will help speed up the search:

1. Clogged Catalytic converter(s). When mine clogged up, basically breaking the guts loose, then re-welding them together with the exhaust heat it clogged up the exhaust, making it impossible to flow any exhaust gasses through, and causing the misfire (resolution - replace cat)

2. Bent valve on #5. This is how mine started, and it took a complete teardown to fully diagnose it, but I had a bent exhaust valve on that cylinder, new set of heads cured it.

3. Might be some easy stuff like a plug wire, cap/rotor/plug thats easy to replace.

If you havent checked on these already, might send that info on to your repair guys.

Good luck!

 

Have they done a compression test yet?

 

Thanks for the help! I am getting the Cat checked out this week. I am hoping that a simple cat replacement will fix the problem. The guy at the exhaust shop doesnt believe it is the problem so we will find out soon.

 

IIRC there was a tsb for plug wire routing. If you don't route the wires right it will cause misfire codes.

 

Somebody explain to me why the plug wire routing would cause a misfire. I had a bad miss. replaced wires, dist cap plugs and rotor button. still missing bad. Replaced the crank pos sensor, now it won't start. It acts like it is trying but no go. Any help on this will be appreciated. I am at my wits end with this thing. Any way to clean fuel injectors?

 

Could somebody help me? I'm lost.

 

could be a lot of different things causing this, my advise would be getting hold of a scan tool like actron or some others, there not to bad of a price. im assuming your mechanic has one, should look at things like downstream o2 sensor voltage(this shows your true A/F ratio) also check fuel trims if there high its adding fuel for a reason if negative its taking away, whats all your plugs look like? are they all the same? does it misfire as engine is warming up,or just randomly at all times? if you can give a little more specific info,you mike get some good responses..

 

I have been experiencing random misfire codes for the past year. I've changed the cap, rotor, sparkplugs, wires, ignition coil, O2 sensor. When this problem first started it would be a rough idle when first started in the mornings and would clear up after a couple miles down the road. About a month ago , the rough idle & missing definitely got worse. Last week I was driving down the freeway and the engine stalled out and would not start. I was getting P300, P301, P305, P306, P307, a code for one of the O2 sensors. The repair shop has diagnosed a bad ECM, hopefully this has been the problem causing all these codes.