Hey guys, first post here, just got my 2005 F150 King Ranch (5.4L) a few weeks ago. I put an Edge Evolution CS2 programmer in it, and it worked great, until it threw the engine into Failsafe 2 days ago. So here's where it gets weird...

When it went to Failsafe, it did NOT have a check engine light, but I did see these codes on the Edge's diagnostic tool:

• P2106 – Throttle Actuator Control System - Forced Limited Power
• P2135 – TP Sensors A and B Rationality - Plausibility Error

Upon restarting the engine, it came out of failsafe, so I reset the DTC codes and continued on my way. That day I did a lot of driving, and it went off 3 times (about every 80 miles). Naturally I thought it was the programmer, so I restored to stock settings and unplugged the programmer. Made it about 200 miles and then it happened again, so it's not the programmer.

So the weird part is it seems that other people reporting these codes are also reporting check engine lights and the truck not running properly, whereas mine still runs great and DOESN'T have the light on. Also, I can't find anybody else having this "rationality-plausibility error". Anyone know what this means?

Anybody have any ideas on this?

Thanks in advance!

 

I would clean your throttle body and stand by to replace if that does not work.

 

Both of these codes are related to the position of your throttle, not necessarily the cleanliness of the throttle-body. If you use your scanner to reset the codes the "limp mode" should reset itself. This happened to me in my truck after going from a slow speed to full throttle. (didn't wanna miss that yellow light). If that doesn't work listen to the comment above me. This code SHOULDN'T warrant a replacement of your throttle body though. It's just your ECM saying "ey wot?"

edit: should have read your whole message. are you an aggressive driver? If you aren't take the throttle real light for a few days, and if that still doesn't work maybe listen to the comment above mine.

 

Could be a throttle body or accelerator pedal problem. Check all the connections at the TB and pedal and see what happens.. You can watch TPS (accelerator position on your Edge).. It should read smooth 0-100%. If it doesn't read smooth then 1 of the 2 locations are your problem, the throttle body being the more common of the 2 points of failure.. A simple TB cleaning like already suggested may a quick and easy fix..

 

cleanliness affects the position

 

lol

 

Yeah, I was meaning to say the position of the TPS and the pedal, not the actual throttle itself. I typed something different than what I was thinking lol.

 

I'm not a terribly aggressive driver, I usually get 16-17mpg if that's any indication. Granted I drive mostly highway...

The truck jumps out of limp mode on its own, and then I am resetting it after that. It's not turning on a wrench light or anything which is what's weird to me.

I'm going to call Ford tomorrow and check on a price for a throttle body. I'll clean it out on Saturday and see what happens I suppose.

 

Take it off the manifold to clean it and be sure to use the correct TB cleaner.

 

I concur with all the above recommendations as prudent and inexpensive first step.

If that doesn't do it, the attached document is an interesting read and may hep. The codes are not strange at all for your described symptom. If you have a scanner that reads live data streams there are about three OBDII PIDs that can help narrow things down if cleaning is not successful.

Here is another very related / similar thread. http://www.ford-trucks.com/forums/14...l#post15782142

Hope this helps.