Brief power loss when accelerating then BANG

[Mike_F]

1998 Limited - 220,000 mi. This happened to me three times, twice under identical circumstances. Cruising at 65 or so on turnpike for 200+ miles and gave it a little gas to pass. Not stomping on it, just accelerating. There was a very brief power loss followed by a loud bang, like slamming into gear or something. I thought for sure something had broken but the car ran fine for a few hundred miles and it happened again. Thinking it was the tranny, I took it to the local transmission guy. He didn't think it was the tranny after driving it and examining the fluid. He checked the tires and found the shortest tire was 1/4" shorter than the tallest and one tire had 15lbs less air than the others . (two different brands on front and back with 30,000 miles difference between the two, the small tire was one of the newer ones) He said this difference can cause problems in the transfer case due to the truck being automatic 4WD. Ford said the maximum allowable difference is 1/8" so I bought 4 new tires, made sure the pressure was correct and everything was fine for 500+ miles when it did it again. This time at slow speed trying to make a yellow light and the bang wasn't nearly as bad. I can't make it do it on-demand no matter what I do.

Any ideas? The truck hasn't had a tune -up in a looong time but otherwise runs fine. I did notice that I have to pump the gas a little when starting cold.

 

[©H®I$]

I tune up wouldnt hurt. If youre having trouble starting your car, it might be your fuel pump. But for the loud bang, I have no idea what that could be

 

[JMan689]

Possible backfire?

 

[RickOTR]

Sounds like the fuel injectors are getting clogged. 220K miles is a lot for fuel injectors. Just a speck dirty will cause problems. Mine does the same thing as yours when the FI's start getting dirty, it will lose power then all of a sudden it will take off. Others things, fuel pump and clogged fuel filter.

 

[1992fordgreen]

If I where you, whether it's running good or not, just do the tune up and be done with it.
Things to do during the tune up would be cleaning the IACV, MAF, setting TPS, changing spark plugs and wires, running a couple jugs of fuel injector cleaner through it ect. Sounds like a backfire, which is usually the spark plugs, I know, I've been there.

 

[Mike_F]

I'll get the tune up but this is not an explosion/backfire type of bang. Its more like the tranny temporarily (1/2 - 1 sec?) disengages, there is a loss of power and then it bangs back in. You can feel it but it happens so quickly, infrequently and unexpectedly I may not be remembering it right. Buts its definitely a mechanical "bang" or clunk or something.

 

[Turdle]

I might have missed it but does the check engine light turn on when you turn the key to on, and turn off when the engine is running?

 

[Mike_F]

It blinks on momentarily as I turn the key to the start position but doesn't stay on.

 

[1992fordgreen]

I can tell you now, it probably has nothing to do with tires then...

 

[R1dd1cK]

Have you done the brown wire mod? It might be something to consider trying that way you can force 2wd and see what happens.