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'97 E350 engine skipping and misfiring getting worse

2K views 4 replies 3 participants last post by  rustyk 
#1 ·
I have an E350 Cargo Van that has gradually developed a skipping problem. It used to be under light engine load at 30-40mph that the engine was bucking and seemingly misfiring. Idle rpm go slightly up and down in 2-3 sec intervals. At higher speeds and during accelerations she runs fine. Power seems OK but she not a rocket. The problem has very gradually over more than a couple years been getting worse and is now so bad that I can not drive at the speeds mentioned without constantly accelerating and decelerating. In the past oil changes corrected or at least improved the situation. We use Ford Motorcraft 15-40W. I have been looking around in other forums for Oil additives but all I can find is DON'T. We are due for an oil change and I was going to use the Motorcraft oil again except I was going to let the engine warm up well so it drains better. Any diagnostic hints and recommendations are most appreciated.
Thanks -Stefan-
 
#2 ·
Replacing your high pressure oil sensor would be a good start. Almost all symptoms you have stated point to this part going bad. Other than that I would replace your CAM sensor if that doesn't work.
 
#3 ·
We replaced the ICP sensor. No improvment. We then changed the CAM sensor. No improvement. We then changed the oil which used to help in the past. No improvement. If any change occurred the bucking is now at somewhat lower speeds say 35mph instead of 40 or 45. I read a lot about rough idling in connection with these symtoms. The idling is not that bad. A friend of mine, an extruck driver, thinks the problem is mechanical. I don't see how that would work on an automatic transmission. The best way to describe the problem is still that the injector timeing seams off (probably to early) under light engine load. I can send a sound file of the engine idling and driving if that would help.
 
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