Bizarre throttle issue

fastersteve · Jan 15, 2023

My 01 Ex in my signature has been doing this for a while and I'm stumped.

Completely ramdomly and intermittently the motor will lunge, as if the throttle was floored. It's very short in duration, never more than a few seconds. If I'm driving it doesn't downshift but literally jumps 1000 rpm then back to normal.
Of course it won't do it when I had AE connected, doesn't set any codes.

I appreciate any helpful suggestions.

Powerstroke Cowboy · Jan 15, 2023

Does it do it with the cruise set?

Could be the throttle position sensor or the crank position sensor.

Tiha · Jan 16, 2023

Could it be the torque convertor unlocking?

If the rpms are jumping under a load, the engine doesn't have enough power to increase rpms that fast going down the road. So maybe the transmission is hitting a neutral position or torque convertor unlocking?

I suppose you could tap the brake pedal while driving and see if it creates a similar response? tapping the break pedal should unlock the convertor for a couple seconds.

Powerstroke Cowboy · Jan 19, 2023

We got a spammer again!^^^^

In line with the thread. The OP must not want help to bad if they don't respond to there own thread....

fastersteve · Jan 19, 2023

Or maybe for some reason he suddenly wasn't allowed to reply.
Have you considered that? Now that that's fixed

It's not the TC unlocking, it does it in idle in park, at speed, completely randomly.
2 different CPS - no change
different IDM - no change
I had considered the throttle pedal, should have a new one today.

Also wonder if the PCM is going bad, it's on number 3 now. Or maybe the hydra? Programs?

Powerstroke Cowboy · Jan 19, 2023

fastersteve said:
Or maybe for some reason he suddenly wasn't allowed to reply.
Have you considered that? Now that that's fixed

It's not the TC unlocking, it does it in idle in park, at speed, completely randomly.
2 different CPS - no change
different IDM - no change
I had considered the throttle pedal, should have a new one today.

Also wonder if the PCM is going bad, it's on number 3 now. Or maybe the hydra? Programs?

That's another reason. Forum's can be a mess sometime. Sorry if you felt like I was accusing you. It was ment more as a comment to get your attention.

If it's doing it at idle in park I would rule out the TPS.

I would unplug the chip from the ECM and see what happens. A bad connection between the ECM and chip can do strange things.

That's crazy you have had so many ECMs go bad.

fastersteve · Jan 19, 2023

Powerstroke Cowboy said:
That's another reason. Forum's can be a mess sometime. Sorry if you felt like I was accusing you. It was ment more as a comment to get your attention.

If it's doing it at idle in park I would rule out the TPS.

I would unplug the chip from the ECM and see what happens. A bad connection between the ECM and chip can do strange things.

That's crazy you have had so many ECMs go bad.

It kinda' did, but worked to make me fix it so no worries lol. Busy packing to move cross country and kept blowing it off.

I will try that before installing the pedal. Maybe the connection is oxidized? I HATE driving it without the chip, sooo sluggish.

I agree on the PCMs but nothing else fixed the issue. Stock one started stalling out, a lot. Tried all the obvious things, reman from Ford worked for several years. Then it randomly wouldn't shift past 2nd gear. Might last a few minutes, or several days, and might not happen for weeks. Towed my trailer from Houston to Austin in 2nd, 50 mph 3200 rpms. That was miserable.

Powerstroke Cowboy · Jan 19, 2023

fastersteve said:
It kinda' did, but worked to make me fix it so no worries lol. Busy packing to move cross country and kept blowing it off.

I will try that before installing the pedal. Maybe the connection is oxidized? I HATE driving it without the chip, sooo sluggish.

I agree on the PCMs but nothing else fixed the issue. Stock one started stalling out, a lot. Tried all the obvious things, reman from Ford worked for several years. Then it randomly wouldn't shift past 2nd gear. Might last a few minutes, or several days, and might not happen for weeks. Towed my trailer from Houston to Austin in 2nd, 50 mph 3200 rpms. That was miserable.

If your packing to move then you are busy!

Maybe it's oxidizing? I do not know,never had that happen to me. But I did.have a chip come loose and case problems and have a chipgo bad and it caused problems. I would definitely give it a shot.

I hear you on driving without a chip. It makes a lot of difference.

fastersteve · Oct 6, 2023

So I just replaced the PCM with a reman from Full Force Diesel. Yes, this would be #4. I'd love it if someone could point me in any direction as to a cause.
It runs much better now, but still does the rpm spike once or twice when cold.
Maybe I need to buy some sage and smudge it...

Powerstroke Cowboy · Oct 6, 2023

fastersteve said:
So I just replaced the PCM with a reman from Full Force Diesel. Yes, this would be #4. I'd love it if someone could point me in any direction as to a cause.
It runs much better now, but still does the rpm spike once or twice when cold.
Maybe I need to buy some sage and smudge it...

Is that with or without a chip?

fastersteve · Oct 6, 2023

With. Honestly when it started and idled normally I assumed that was it. I'll have to try it without.

fastersteve · Oct 8, 2023

I haven't run the new pcm without the chip, but when I pulled the chip out of the old pcm it continued to act up, so I'm inclined to think it's not the chip.
Could a failing IPR do this? My understanding was that they either work or they don't.
I'm open to reasoned suggestions.