'00 "Dgoo" R/T, 60k, auto, 4x4
At cruising speed no matter 35, 55, 83 mph the motor misfires on cyl. #6 and #3 and really starts to buck hard. Under acceleration or idle the motor runs fine. I have changed cap,rotor, wires and champions (gap.040) all purchased @ dealer (dummy me) and the TPS, and the thermostat (195). THERE are NO codes. The tranny is fine. The plug wires have been routed as per ********* Compression in cyls. is NO less than 150. Anyone have similiar probs. or solution? ALL help would be appreciatted.
Thank you
jnr

*please don't advertise othewr sites on DF*
Casper

 

what about a fuel system problem. I wonder if you have injector thats not fireing properly

 

The injectors checked out fine and the PSI is checking out good.

 

Some of the things u might want to check are,

1 fuel preasure when driving the truck and it is acting up.

2 check and make sure the cat convertor is not starting to plug up, do an exhaust backpreasure check.

3 make sure the EGR system is functioning as intended

4 not to sure if 00 had an intake problem but check to see if the intake belly pan has a bad gasket this can cause a leen misfire at crusing speeds

5 make sure you have a clean signal coming from the O2 sensor so the proper amount of fuel can be delivered at all times.

6 if you have access to a scaner take the truck on a road test and moniter the misfire counter to see if this is what is happening at the time it is acting up.

I will get into the books for u and see if there are any tech bullitins on your truck because there may be a flash update for the computer .

And most of all thanx for the confidence in me.

I will answer back after i get into the books for you , in the mean time if u figure it out let me know what you find.

 

could be spark blow out, not sure if it would be though, try to gap the plug a bit closer, that happened to me on my stang, although im running a blower, its worth a try. good luck

 

I had the same problem with my 98 5.9, and it ended up being rusty fuel rails clogging my injectors. With this problem there won't be any associated codes, except the misfires, and your fuel rail pressure will check good. The good thing is, the fuel rails and injectors are easy to pull and clean, so if it is not the problem it has not wasted to much of your time.

 

Ok heres an update, Thank you ALL for your ideas, I have to try them out because I was 700 hundred miles from home on a family vacation with the truck when this happened. I had the crank and cam sensor replaced while on vacation, dumped 4 fuel system cleaners (Lucas Fuel Cleaner) in the tank as Lucas recommended on the way back. On the drive back system seemed fine until about 500 hundred miles into it and she started bucking again, not as bad, seems to happen when the truck gets ran for a few hundred miles. Also the porclein electrode on the the plugs are BRIGHT white not the yellowish/brownish expected to be. The bright side to this is my MPG's went from 11.6 to 14.9 on the highway.

Again Thanks to all !!!!!

 

I'll bet you have an intake manifold gasket leak.

 

When my fuel pump started going I got a similar response.
When it was below half a tank I got misfires; ran fine above half a tank.

 

Ok, another update, took the truck to Dodge dealer today. They replaced the coil for $ 235.00 and said wort-ho thats the problem. Well they called back after a test drive and said the timing is 20 degrees off, MUST be the timing chain and gears need to be replaced at a cost of nearly a BIG G ($1000.00) I asked if the distributor gear could be off and "they" said "its the timing gear and chain". Hmmm
I am bringing the truck home and thinking of checking the distributor gear myself first, any thoughts?

Still bucking
Rick