Accelerator Pedal Position (APP) sensor maintenance w/pics
 

Ok, so what do you do on the first 60* day of the year? :-wow Something on your TRUCK! Knowing how you guys love pictures, I snapped a few. :-innocent

While trouble shooting my IDM issues, noticed that my skinny pedal had a "dead" spot just off idle, and decided to investigate... see if I could clean or service it back into specs. The AE was showing a change in voltage, but the engine wasn't responding. :-roll So it may in fact be fine, and instead is the chip, don't know. Anyway, here's what I found.

http://i110.photobucket.com/albums/n...h_P1050492.jpg http://i110.photobucket.com/albums/n...h_P1050498.jpg http://i110.photobucket.com/albums/n...h_P1050494.jpg http://i110.photobucket.com/albums/n...h_P1050495.jpg http://i110.photobucket.com/albums/n...h_P1050493.jpg http://i110.photobucket.com/albums/n...h_P1050497.jpg
This is the assembly out of the truck. Prior to disassembly, you can see some wear on the fulcrum and also note how the Idle Validation Switch (IVS) is activated.

http://i110.photobucket.com/albums/n...h_P1050517.jpg http://i110.photobucket.com/albums/n...h_P1050519.jpg http://i110.photobucket.com/albums/n...h_P1050518.jpg http://i110.photobucket.com/albums/n...h_P1050506.jpg http://i110.photobucket.com/albums/n...h_P1050504.jpg http://i110.photobucket.com/albums/n...h_P1050511.jpg
Here the IVS is removed to show how the lack of lubrication has scored the lever pretty significantly. There was also a fair amount of crusties around the actual switch under the lever, and some yabbies between the potentiometer and pedal assembly.

http://i110.photobucket.com/albums/n...h_P1050522.jpg http://i110.photobucket.com/albums/n...h_P1050523.jpg http://i110.photobucket.com/albums/n...h_P1050510.jpg http://i110.photobucket.com/albums/n...h_P1050502.jpg http://i110.photobucket.com/albums/n...h_P1050527.jpg http://i110.photobucket.com/albums/n...h_P1050530.jpg
Here is how I cleaned and lubricated the pivoting points/fulcrums and the products I used. The last shots were the result.

http://i110.photobucket.com/albums/n...h_P1050499.jpg http://i110.photobucket.com/albums/n...h_P1050508.jpg
Part numbers on the pedal assembly, and the potentiometer.

Outcome... well unfortunately the "dead" spot appears to still be there, BUT, the pedal is much smoother now in application. Also I believe I may have added some life to my IVS after seeing the condition of the lever. While I cleaned and lubed the assembly, the lube application was minimal as not to attract dust and debris. Hope it helps someone, I still may have to purchase a new one, need to figure out how to test it first. :-X22

Reps for the writeup and pictures! Another project to add to the growing to do list.

Just slightly O/T...whats the highest voltage or % you can get out of the pedal? Mine maxes out around 87%.

Nice pictorial. Is this the sensor original for early 99?
Mine was chocking on acceleration last summer, but doesn't do it anymore now.
I wonder if spending $50 for a new one would be good insurance?
Is there other way to control throttle when the sensor goes kaput?
Maybe CC, but the one on my truck died as well.

I have a different take on this. My sensor recently went bad; it is the early design also. When I stepped on the go pedal, it wouldn't go unless I "pumped" it a couple of times, just like a carb.
This problem didn't seem that bad until suddenly I was out in an intersection trying to make a turn and it wouldn't respond with on-coming traffic, and that was scary.
I would not recommend attempting a cleaning or repair except as a very temporary measure, but instead replace it as quickly as possible.

Always wondered what the IVS looked like. I somehow managed to break the pedal part off my accelerator haha. Need to fix that sometime, but Ford thinks their pedal is worth its weight in gold, just like most other parts.

This is the original APP installed on my truck in September, 1998. :eek:

Well in my case, it was acting like debris may have been impacting the "smooth" transition of voltages. No indication there was a short. It responds as designed, but most notably after a small acceleration, if you let off the skinny, you'd have a sharp "jolt" from the drive line caused by "sudden" deceleration. Mind you, I would only be casually letting off the pedal, but it felt like I let the pedal spring back to the up position.

Good news is today it's completely back to normal. I can ease off the throttle, and have the engine "ease" off acceleration! I'm pumped. :-jammin So, perhaps it took a little bit for the CorrosionX to work its way into the sensor. Definitely a worth while procedure for me. From the looks of the IVS, I'd say in a year I would have rubbed through the lever.

mine has that dead spot, but only once in a while. nothing like trying to leave a stop sign with no juice, then all of a sudden it wroks and Veerooom. lol

It sure would be great information to know if this is a permanent fix - any updates over the next few months would be appreciated.
I neglected to mention that at times under mild acceleration the transmission would buck and kick. Fellow FTE-ers identified the TPS as the problem.
A known good used one solved the problem right away.

Yep, you can count on it... Just for clarification, under acceleration it really didn't have any problems. I'd have to very gradually depress the pedal to notice the engine wasn't reving, even though I know I was off idle, and voltage was increasing (confirmed by AE.) My biggest indicator was on deceleration. It went from a gradual decline in RPM, to dropping off right before the IVS would activate. The unit seemed pretty tight, but after 10 years and ~250k miles, stuff is going to get in there. We'll see if the CorrisionX managed to "creep" in there, clean and lube a little. :confused: I thought the thing would cost over a hundred dollars... for $50, I might have just replaced it... wouldn't have been as much fun though :-X10

Excellent write-up and pics. :-X22 Reps sent.

2001 F250 7.3 -- stalls on start
 

Hi guys,

I am not sure if what is going on with my truck is the same thing you guys are talking about. The truck only has 65K miles and is in pretty good shape. It has always done this but here recently it has good from once every couple of months to many times every 30 minutes. I release the brake and start to accelerate and there is just nothing there. The truck goes forward due to normal idle speeds but there is no response from the vehicle. I think start into a mad dash of stomping on the accelerator and then eventually it will take off. Sometimes up to 3 to 5 seconds. Doesn't sound like much but when you are halfway into an intersection.... Sometimes the Check engine light will come on during the time the engine or accelerator is non responsive...once the truck responds, the light goes away.

Once the truck does this once in a given trip, then it seems to do it more often on that same trip. AND, eventually, the transmission wants to change to third gear right away. OF course this makes for some rough driving because the engine speed is too low for third gear and it tries to go back to second gear...which of course sends it right back to third gear.

This sounds pretty scary to me, like it could need some serious repair but once I restart the engine, it seems to reset and transmission things works out until i start having the unresponsive engine again! Any suggestions? beside drive it into the nearest lake??? :)

Your symptoms sound like the IVS (Idle Validation Switch) has bad or dirty contacts. The IVS contacts are normally open and close when you press on the pedal. If the PCM does not see the contacts close it ignores any signals from the TPS.

1999-2001 have a separate IVS and TPS. 2002-2003 have a combined IVS and TPS.

I wish this would be my fix. I have the combo switch. I get a intermitant dead pedal. very exciting when you drive a handshaker. try pulling a 6% grade with and 18K trailer, go for a down shift and have NO THROTTLE. tends to piss you off. Blip the pedal a couple of times and it comes back. I've replace the pedal 3 times in the last yr. 2 OEM pedal and 1 aftermarket. I finally decided it had to be the connector. I cleaned the contacts and used a contact enhancer. thought I had it. 3 days later it does it again. So today I replaced the connector. It dropped out once already. any other ideas? I struggling here.

Barney

Man, my buddy Barney is going thru mid life truck madness:-wow. Sorry Barney, not busting on yaa, just hoping for a relatively easy fix..

Thanks for the info