2003 Ranger,4 Cylinder, 2WD-72,000 miles

I was making an 800 mile drive recently and noticed a strange problem WHen cruising at highway speeds and going uphill the truck would sort of hic-up. No noticable difference in noise but it would sort of jerk. When I downshifted to 4th at rapped it out, no jerk. This went on until I reached my destination. Driving around town, no problems.

On the return trip home I had the same problem. This time I also noticed it under hard acceleration trying to merge into traffic. Whenever I tried to go uphill, same thing. The problem became more frequent the longer I traveled.

Now driving arount town, no problem. Placing any sort of load on the drivetrain, the jerky hic-up happens.

Things I have tried: Code Reader-No Failures, replaced gas, fuel filter, utilized 2 doses of fuel injector cleaner, new spark plugs, new wires.

Any ideas?

 

Has your timing belt been replaced? My escort gets that way before its ready to break. The Escort goes at 50K. Not sure the recommended milage to replace Ranger 4 cylinder.

 

My engine has a chain instead of a belt. They are not known for breaking. There is not set replacement schedule.