Possibly small issue but desperately need help

[Greg R]

Howdy all, Let me start off by saying I am not a car guy, I don't know what parts are what for the most part but am aware there is no blinker fluid so thats a start right?

Ok I purchased a used 2002 ford explorer xlt, was talked into it by a mechanic (if you want to call him that). Right from the start he said there are issues that need fixed small items.....that ended up being larger items. He changed the tranny, a few sensors, changed all but one of the spark plugs (because its stuck so hard he said if he tried getting it out, it may strip the head and he didnt want to deal with retapping it). After all issues he claimed were a issue we finally got it on the road. It was great for the first 100 miles but then the issues started. Let me say also that I think this was a rigged deal, he knew the person we bought it from and believe he may have did this so he could not only get a cut of the sale amount but also over the 1500 in labor he got additional.

The issue it has now and again forgive me for sounding dumb or not explaining correctly, it drives great at around 20-30mph but after that it periodically lunges. In MY opinion, it sounds as if when its trying to shift gears it doesnt do it right. So while driving, the rpms drop to zero, it jerks/lunges forward just for a second, sometimes it happens 2 or 3 times in a row and then continues driving fine. During this issue it sounds as if the back tires just...stop for a second I hear a skidding sound in the middle of the lunge. I am lost at to what this issue is and I am in the back woods of PA, I don't trust this mechanic who I think of as just a parts changer at this point. He did take it to a friend who hooked it up to a 'super computer' we witnessed this and it did not show any error codes. I am financially crippled, I have no other options other than trying to fix myself. Any help on this issue will be GREATLY appreciated. I have a low wage job, my wife is on disability and what we put into this is all we had which we are still paying someone back for a loan to get this....

 

[extra-medium]

I am not positive but it sounds like either the trans, transfer case, or rear diff. I am not too familiar with trans problems, but how I understand them it sounds like the trans is locking up when it shouldn't be. Maybe an issue with the torque converter? Good luck with it.

 

[Number Twelve]

I had this problem with a Buick Skylark. A broken vacuum hose, made of small diameter, hard plastic. The hose was replaced with rubber vacuum hose. The flexibility of the rubber resonated with something and the car would go into bucking and backfiring at certain throttle positions. I could keep it in that condition as long as I held the gas pedal in the right (wrong?) position.

This might have nothing to do with you, but it won't hurt to inspect every vacuum hose to be sure it's the original kind of hose.

 

[rrgone]

Is it 4 wheel drive? If so, it might be kicking in and out of 4WD on you. You can find out by pulling power fuses 17 and 18 in the battery junction box. You got other good ideas here too. Let us know what you find out.

 

[Greg R]

Thank you all for the ideas. The wife said she already pulled the fuses and it didnt help, she put them back in after test driving it BUT right now, the 4x4 auto light is on and wont go off.