1998 XLT with 248000 miles, out of control acceleration

[coax31]

Hello,

I have 1998 XLT with 248000 miles, lately it has sporadic out of control acceleration where you have to put it in park and it keeps accelerating until the engine is turned off. This condition only occurs sporadically and I can’t reproduce it seems to only happens when my girlfriend drives it. She is not using the cruise control and the floor matt is not jamming into the gas pedal. I don’t know if it is the gas pedal, the throttle cable or the throttle body that is causing the issue?

thanks

 

[Dono]

Sounds like your dead on in your diagnosis.

Try popping the hood (engine off) and flipping the throttle body butterfly back and fourth where the throttle cable attaches to the throttle body. Feel for sticking.

 

[coax31]

Cable seems to move freely no binding

 

[R1dd1cK]

it could be a sticky IAC valve

 

[coax31]

Wow if a dirty or wore out IAC causes this condition that is a bad deal which could cause potential death. I may just swap it out anyway.

 

[Dave 1955]

Never heard of this prob.

 

[Dono]

Ive never seen a stock setup do this either.

Maybe the key here is that it only happens when the girlfriend drives it. Very intermittent.

Try pushing the gas peddle down by hand and feeling for something sticking.

I cant imagine the iac valve opening so much that the motor revs uncontrollably. a stuck open iac valve is only good for a 2000-2500 idle. I know this from experience.

 

[SmokedExploder]

I just recently purchased my Explorer and it had this same Issue but all the time, it would accelerate crazy on its own at Idle, higher RPM`s than normal. Cruising at 80km/hr let off the throttle and you would basically maintain the same speed and not slow down. Made the brakes work for sure.

Sent it into the shop for the certification ($2,000 total)

Turns out it was the Wiring Harness, my O/D OFF light was always on too. Well the Wiring Harness fixed everything. The fluctuating RPMs up/down, no O/D light now etc. all is good

 

[1992fordgreen]

^you dont want that to be it...believe me! Kick in the butt.

 

[coax31]

Had the mechanic look at it , he cannot find an issue he did clean the TBI real good and WD40 the accelerator cable. He said the TBI was real dirty

 

[koda2000]

i think the only way this could happen is if the throttle plate or cable is getting stuck. if it does it again, now that it's clean, replace it before you kill someone.

 

[bobflood]

Check to see if the under dash bracket for the gas pedal is deformed/broken. It is spot welded to the inside of the firewall; those spot welds can break and let the bracket loose (ask me how I know!!) I just drilled out the welds and replaced with locknuts/bolts. Good luck.