My dad has a bone stock 1996 ford ranger 2.3L, auto, 2wd. It developed an oil leak so he carried it to a ford service tech to have it fixed. The truck ran perfectly before he carried it in for the oil leak repair. The tech replaced the crank seal, oil pressure sending unit and valve cover gasket because he found leaks from all three areas. While he had it torn down, recommended to my dad that it would be a good time to change the timing belt. It had been about 40K miles since it was changed so my dad gave the okay on replacing it. Well, when this was being done, he found another leak from the water pump so that was replaced too.

My dad got the truck back from the repairs a few weeks ago, and ever since he's had it, it has had an off idle hesitation. When you mash the gas quickly, it bogs for a second and then picks up. Bascially it does it any time when more than 1/4 of throttle is applied from a stop. The truck also had a rough idle.

The first thing I checked were the vacuum hoses for leaks/cracks. I didn't see any problems, feel/hear any leaks. The next thing I was told was to remove the spout from the firewall and check the engine timing. From internet research, this was supposed to be 10*. My light showed 18*. So my dad carried it back to the mechanic and got him to check the alignment of the gears. All of the dots lined up. So, he put it back together and dad borught it back home. Next I replaced the fuel fillter thinking there could a a slight blockage that the fuel pump was having to overcome at low engine speed. This didn't fix the problem either. Then, I took the throttle body off, cleaned all of the soot off the blades and in the bore, and cleaned the IAC valve with some electical parts cleaner and reassembled it. This helped with the rough idle problem, but the hesitation off idle is still there. As a last resort, dad put some of the fuel system treatment in it and has run 2 tanks of gas through it since then. The problem is still there.

Any ideas?

I know its something the service tech did because it ran perfect before. Just figuring out what was damaged/installed incorectly is my problem. The only other thing I can think of is a camshaft or crankshaft position sensor. Does this engine have either of these?

 

Take it back, very simple, why spend your time or money in trying to track down something a tech did? If it was mine, I would stop trying to diagnose something and bring it back.

 

My dad took it back. He couldn't fix it. That is the problem.

 

Then I would take it to another shop, have them diagnose it, take that back to the origonal mechanic, an ask if he wants them to fix it or will he. You will have to apply pressure because he will be loosing money by going back into the motor.

 

He is going to do that. However, I was asking for ideas here before we took it. If it is something simple to check/diagnose/repair that I have overlooked, why take it to a shop and have the truck tied up for 2-3 days? It is his daily driver and he has nothing else to drive to get around, so if I can fix it, it would be better for him. When it was initally repaired, I was out of school over winter break, so he drove my car to work until he got the truck back the first time.

 

Hey, have you ever resolved this? I have the same off idle hesitation in my 97 Ranger (2.3), with no repair history. A while ago I had put the TPS on an oscope and found a tiny hiccup in the return voltage--must have been an open in the potentiometer--and replaced it. It seemed to run better for a while, but either it slowly has gotten worse again or I was imagining it was better.

Back when I replaced the TPS I also cleaned the MAF and IAC, so I don't think it could be either of those (this was about 6 months ago). Of course, the air filter is fine, and the truck idles and accelerates smoothly at all other times than right when coming off idle.

Any input?