My 2002 Dakota with a 3.9 (200,000 miles)has a problem that I cannot seem to cure.
When I start the engine it never hesitates…it starts without a problem. No excess cranking…it fires up as it always did.
It does run a bit rough as if ONE cylinder is missing every few revolutions. If I let it idle in the driveway for five minutes it will clear up and run fine. But if I take off right away the following will happen.
I put it in gear (automatic) and for the first mile or two it runs as though the plug wires (More than one) are wet and arcing. I can barely get above 25mph. it will spit and sputter for that first mile or two.Then suddenly it will clear up and surge…probably because I have loaded the system with excess fuel…and after it clears up , I have no other problems with it weather I’m on a long trip or a short one.
If I stop for more than 15minutes, I have to go thru all this again.
I’ve had vehicles that acted like this after a hard rain because the plug wires were old and arcing…that’s why I use that as a description.
I also noticed that the other day right at the end of a big downpour it took at least 5 miles to clear up.
Before this rainstorm I had replaced the plugs, wires, rotor and cap, while inside the shop so everything should have been bone dry except for all the humidity from the storm. After starting I checked for any arcing while in the dark shop and even moved a few wires that were touching and no arcing was seen from the cap, wires or coil.
FYI I also changed out all those parts 6 months ago when I did a major tune up, but it ran fine untill about two months ago.
When this started two months ago is was just a rare occurance and my mechanic thought that I had gotten some gas with water in it. He had me run a few bottles of injector cleaner it the next few fill-ups and I’ve run a few bottles of heet through it also. In the last two weeks it has been doing this every time I start up. When this did start showing up it would show a code of a random misfire and the engine light would come on even though I felt no signs of a misfire myself. The light would stay on for a day or two then go back off. A few days later it was back on.
I thought that I fixed the problem because the light stayed off for a month.
So it has been only the last two weeks that it bucks and kicks so bad at a startup, but you would think that an engine misfire would show up and the engine light come on. By the way the light does work.
Now, I never get a engine light on, and he found no codes in the history. I have my own scanner, but his can do so much more. I never find any codes also.
My mechanic ran some diagnostic’s and found an up-stream 0,2 sensor bad so we replaced that.
Yesterday I dropped the tank, pulled the pump and cleaned the tank real good. The only filter is the sock on the pump and that was clean. I refilled with fresh gas and I still have the same problem.
So I think that we can eliminate water in the fuel, plugs, wires, rotor, and cap.
My next thought is the cam sensor in the distributor.