EDIT: Solved my own problem. I figured to make this thread not completely useless I will add information regarding my experience with the APPS for anyone who comes across this in the future since it seems to be such a prevalent problem across many cars and makers including ours. I will also attach the pages from the service manual in regard to installing/testing the new sensor. For reference, pin 1 on the APPS plug is the pin closest to the pavement on my car.

I first started having APPS issues around 60k miles. Slight power shudders or hiccups when cruising. Now at 120k miles the sensor was failing to the point where I could barely drive the car. I looked like a teenage girl learning to drive stick. Frequently the sensor would throw a code and put the car into limp mode with a 3000rpm rev limit. I dealt with this by shutting the car off for 30 seconds and turning it back on (rev limit lifted to 5000rpm, CEL on). Eventually the CEL would turn off and the car would return to normal. Oddly, this behavior across the board is completely non-existent if the ambient temperature is below 85 degrees F; during winter my car worked perfectly normal. This may be exclusive to my sensor, though.

My sensor behaved in the following way once it began to fail badly. When depressing the throttle from any point throughout the pedal stroke, instead of a smooth linear increase the sensor would momentarily "drop-out" and decrease its signal by 5-10% and then quickly jump back up to the actual pedal position. Using my scan tool, I could see the dip and jump clearly on a graph of throttle position. This caused the shudder, or jerking effect similar to that of someone unfamiliar with a clutch. Quite embarrassing.

The part number for the new sensor is: MR578861
After I installed the new sensor I had a problem with the RPM idling way too high. 30 mins of the battery disconnected solved the issue.

 

Good detective work. Thank you for the report and addition to the RA knowledge base.

 

Yea I had these exact same issues. Replacing the APPS sensor fixed the issues for me.

I just wonder why these are so prone to failure? No Revision to this part? Seems scary that once you get higher up in millage any day it could go out and require you to shut the car off and refire.

 

Mine did this a while back too. Except it would only act up when the humidity was high. Im assuming corrosion, or simply wear contribute to this problem. The location of the APPS seems odd to me as well. Seems like it would have been much safer if located under the dash somehow. I dont see the point in needing such a long throttle cable if its just going to a sensor anyway...

Anywho. Nice write up!

 

This. This. This. No idea why the thing couldn't be mounted ON the pedal even. But no lets run a 10ft cable PAST THE THROTTLE BODY to a sensor that controls it...lol.

Thanks for the pic, added up top!

 

Probably because the car could have other engines like the evo7's and i thinks that one was still using a regular wired throttle body so its probably less expensive to build the car in the manner they did.

As for me i have started experiencing the same issue but it just stops the throttle from working.
I turn it off and back on and its ok. It seems to re-apear randomly. I wont be able to get to 3k rpm. The pedal fully depressed there is a wait, and then it launches very very slowly. I sure wont be getting up a hill... This could be very dangerous since in traffic when entering a passing street if i loose my power i could get hit by traffic.... I have asked the dealer for the mentionned tsb but they told me there is nothing for my model year regarding the apps.

By the way mine is a 2004 outy and 4G69 auto.
My code is P2138
The problem does not seem to be related to humidity but might have a link with hot weather..
The car seem to have very slight hiccups( that most would not perceive) and i was thinking of getting sparks but it might be related..
I have the shop manual and i have performed the tests and it could be the connector pin 7 of my apps harness since i have a abnormal resistance. I still have some tests to make but i hope its not the computer.
I still have to test between pin 7 of the apps harness to pin 96 of the computers harness.

 

how much resistance did you get, and what terminals were you measuring?

 

17 ohm on terminal 7 to ground on the harness side of the apps

Pin 96 on the computer is ground so i still need to check the harness side of the ecm

 

Sorry I dont come by here often and this may not be related to your problem but check it out...

 

The dealer told me that this tsb does not exist when i asked them. Now with your pdf i will try again. I have found an abnormal resistance on the sensor switch so.. Probably i just need the 280$ sensor...

 

happened to me 2 times...
i wanted to buy the sensor but couldn't justify spending almost $300 on a sensor was still working 99.5% of the times...

there were more maintenance and/or repair parts to buy more in need than it..

altho my sensor would fault and then it wouldn't go OUT of limp more until i cleared the code...no matter how long it would sit...
i was working at a shop at the time so i was able to find the closest related shop and have the code pulled and cleared, then carefully went to the closest dealer(IIRC ~20 miles away)

they told me there was a tsb/recall and gave me the printout(don't remember offhand now tho) and there was a reflash to fix the problem...so i paid for the reflash(~$100) and problem was "fixed" for the time being

then the second time(about a year later) it happened, i was just as far from a related shop to the closest dealer...so i just limped over to the dealer going 20mph for like 45 mins

they told me the same thing as before....do the reflash, and it's fixed...
so when i told them it's the same symptom as last time, the same code AND i already had the reflash done they just looked at me and went...."oh...umm...well then, you need this sensor....it's a very common problem"

i said no, i'll get one myself and install it(not that i could afford one at the time anyway)...and they argued with me telling me it needed to be programmed after install for it to work....and it required their computer, plus an additional 1hr for the programing...

 

Bull, it is not necessary to program using mut. It is explained how here.

 

i knew that at the time...
plus this was like 3/4 yrs ago when i this happened to me

sadly i dont own the car anymore(miss it all the time....specially when i come into evom)...and now i'm 2 cars later

 

I have a problem connecting the wires please help me