Otay, I need all the help I can get. I've got a 99 Ram 1500, 5.9L, gas, 2 wheel drive that is literaly driving me nuts. I rebuilt the tranny and it is working great. But I developed a misfire in cylinder #6. Here is what I've done to fix this. New Cat, upstream O2 sensor, plugs (Autolit platinum 5442), plug wires, cap, rotor, crank sensor, plenum/intake gasket, set fuel sync, re-programmed PCM and a partridge in a pair tree. Diagnostic test shows high hydrocarbon output. Cleaned TB when replaced plenum gasket. Swapped injectors (6 for 2), no change. Moved #6 plug to #2 and picked up a misfire in 3, 5, 6, 7, & 8. Moved plugs back and down to a 6 & 8 misfire. Swapped plug wires with different ones and no change. Compression is at 110 in each cylinder. #4 plug is the only one that is dark (not oil foul) but might be where hydrocarbon reading is coming from. All other plugs are clean and no sign of fouling. Getting good spark out of each wire and plug at idle. Ran plug wires according to Dodge TB to prevent cross firing. Noticable miss at idle, acceleration is poor, especially up hill. Getting noid fire at each injector connector. Check engine lite will not stay on. Flashes so no code to read other than "pending code" which shows #6 & 8 misfire. All fuses/relays are good. Only had #6 misfire until I swapped plugs then got the multiple misfires and never messed with odd cylinder side. At a total loss where to go from here. Any recommendations would be greately appreciated. Been working on this for 3 months and truly frustrated. Thanks for any help in adavance.

 

110 is right on the edge for a working motor, and lack of comp is more than likely the cause of your miss. Did you do a wet and dry test. I hope I am wrong but you might start looking for a long block. Wait and see what others post.

 

How did your spark look? Did you get a nice fat blue one? What brand O2 sensor? Does it do this consistently? Only when warm/cold?

 

Merc225, HeyYou,

Thanks for the replies. Seems I have a typo on my compression. I do have 120 in each cylinder (plus minus 3-5 difference). I did do a dry and wet test and no change. The miss is there from the start, but seems to become more pronounced as the engin warms to op temp. The O2 Sensor is a Bosch and I've read about them not working all that good in a Dodge. My OBII reader does not get any O2 sensor error code unless I unplug it. The spark out of the plug wires would light a cigar, but doesn't seem quite as powerful when I short out the plug on the engine block. Once I get to speed if I run around 52mph I pick up a noticable shutter and the check engine light flashes. The light won't stay on, just flash then go away. No code to read other than when I check pending code and get the misfire in 6 & 8. Damndest thing I've ever seen with just swapping plugs I got mutiple misfires and switched back, cleared codes, and got 6 & 8 only. The fuel fouled plug on cylinder 4 is a puzzle as well. Getting fire and obviously fire but not sure why that is the only on that if fuel fowled. Could there be a blown head gasket between 6 and 4 cylinders? Doesn't explain #8 misfire and fowling in #4 tho. Appreciate any thoughts on this. I've about run the gammet of my shade tree experience. Thanks again for the replies.

 

Nasty words: plenum gasket failure..

There's a sticky on it at the top of the board.

 

Well the fsm says 100psi min and you say 120 give or take a little, 120 is still low. As for your test results, If compression does not improve on a wet comp test, valves are sticking or seating poorly. How many miles on this motor?

 

Maybe I misinterpreted what you said, but you did say gasket and not new plate, right? Have you checked inside the manifold since the work?

 

Do you have any non platinum plugs you can try, its worth a shot.

 

Check primary and secondary coil resistance.

I did not have good luck with platinum plugs when I tried them many moons ago.

 

Aim, not to hijack this thread, but what plugs work best for you? Modified intake and alum plate (not installed yet), bought cap, rotor, and wires, but still undecided on plugs.

Back OT, from what I have read here, relpacing plenum with aluminum plate is sound investment on 2nd gen Rams.