99 Powerstroke- cuts out while driving, returns to idle... wierd? FIXED!!!
 

Hey guys, This truck runs great, but when you are driving, out of the blue the accelerator pedal will go dead, the engine does not miss, it just returns to idle. Then as this is happening, the "SES", Wait to start, and Water in fuel light come on for a second, and then go back out. The truck will be fine if you take your foot off the throttle, and then push it again, that is, until it acts up again...

I have swapped the Throttle position sensor, no change...

It has a P0122 code for the TPS circuit, pointing to a "Fuel and Air metering module"

Any ideas guys?

Thanks!

sounds like the Idle Validation Switch isn't working. does your pedal have 2 switches or 1?
2 switch pedals= 1 TPS and 1 IVS. 1 switch pedals are a combo switch.
IVS is a simple off/on switch. if it drops out the truck will return to idle no matter the pedal position. check your harness and contacts. some folks on here have had success cleaning the switches with contact cleaner. me not so much. I've replace my pedal 3-4 times. one OEM and one NAPA. I just keep a spare with me now. its a simple 10 min deal.

Barney

Here is some info for ya.. that might help:
https://www.ford-trucks.com/forums/9...ensor-fyi.html

Thanks a bunch guys, I just got back to check the thread. I had come to the conclusion that it was the IVS, and this info supports my conclusion.

Thanks, will report once I change the IVS.

Well guys, Just my luck... I changed the pedal assy. and it didn't change a thing. :-arrgh (I can return it thankfully)

So today I did a lot of diag. on it, and here is what I have found so far....

IVS seems to have steady 12v power coming in, but drops the signal going out occasionally (then the truck returns to idle etc.)

I was monitering the TPS incoming signal wire with one voltmeter, and had another on the IVS outgoing signal wire. Then I hooked the voltmeter probes up to the Snap-on Modis, displaying the voltage on a graph.... I notice a sudden spike and then a huge drop in voltage whenever the pedal goes dead, and the wait to start light comes on as soon as this happens. (also, when the pedal goes dead, the voltage going out of the tps is right where it should be{meaning it goes up and down depending on how far you push the pedal} but you have to open the IVS curcuit before it will accelerate again)

Based on what I see from my research, it seems like the PCM thinks that the truck was quickly turned off, and then right back on, because that is what must be causing the wait to start light to come on.

If anyone has any ideas as to why it is doing this, or what is causing it, I would be very appreciative!!!!!!! It is starting to frustrate me :)

P.S. I also swapped the PCM power and blower motor relays and it made no difference.

Subscribing, Unfortunately I dont have any help to give, but my truck does the same thing every once and a while, without the dash lights coming on. Hope you figure it out soon.

Check your IDM. My truck was doing the same thing for a little bit and I couldn't figure it out to save my soul. Finally died on me on the highway one day. Had it towed to the ford garage and they figured it out for me. Mine fried as a result of a shorted wire on the valve cover.

The replacement part from ford is 900 bucks. You can get them online for much less though.

I can try the idm, but it seems like the engine never has an issue, it simply doesn't respond to the throttle.


Any other ideas?

nothing?????

I just spliced in a new pigtail connector for the TPS, with no change. I am trying to locate a PCM and IDM to swap in. I have them for the OBS trucks, but no Super duty ones.

Just a shot in the dark but are you blowing any fuses at all in the fusebox, preferably #45, its a 10 amp fuse. It just might be the od wire under the steering collumn in the begining stages of shorting out. In my case I had those symptoms but blew that fuse but its worth a look. Search in the 7.3, go advanced with the search for greater accuracy, punch in steering collumn shorts, theres a few to look over, including mine I started, good luck.

Thanks! I will check into that info, it doesn't seem to be blowing any fuses, but it is deffinately worth checking into. My frist thought would be a short somewhere, because the owner of the truck said it seems to get worse on turns and bumps.

Well, I unhooked the batteries, and then unhooked and inspected, and then rehooked the PCM connection, reconnected the batteries. Problem fixed. We'll see if it reoccurs with time...

Thanks for the help that was given. Reps coming!

Did you ever have any more trouble? My 2000 was having the exact same issue and yesterday I did what you did (along with some other connectors) and so far so good! Thanks for posting your fix, it's rare but so very helpful.
:-drink

It was a customer's truck, and no, he has had no more issues. Good to hear you got yours fixed. Glad to be able to help.