Go Back   Ford Truck Enthusiasts Forums > Newer Light Duty Trucks > Expedition & Navigator
Sign in using an external account
Register Forgot Password?


Expedition & Navigator 1997 - 2002 and 2003 - 2006 Ford Expedition and Lincoln Navigator SPONSORED BY:

Welcome to Ford-Trucks Forums!
Welcome to Ford-Trucks.com.

You are currently viewing our forums as a guest, which gives you limited access to view most discussions and access our other features. By joining our community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join the Ford-Trucks Forums community today!





 
Reply
 
LinkBack Thread Tools Search this Thread
  #1 (permalink)  
Old 01-01-2010, 01:38 PM
ResJudicata ResJudicata is offline
Freshman User
 
Join Date: Feb 2007
Posts: 31
ResJudicata is starting off with a positive reputation.
Code P1121 = sticky TPS (this time)

I have been having an issue at very low temperatures. When the temp gets below 20 degrees I would occasionally (but more regularly the colder it is) have a VERY high hanging idle and the trans wouldn't shift out of first. If I let the truck warm up while stationary it would resolve itself until I drove it for a while and then come back.

I finally had a CEL come on yesterday when the above happened. I went by Advance Auto and used their code reader and got a P1121 code. I then checked what that code meant on this forum and found:
P1121 Throttle Position Sensor Inconsistent with Mass Air Flow Sensor

I checked the TPS and found the voltages at idle and wide open throttle to be quite off. I was getting very little change in voltage and the voltage was high at closed position. But, what I also found while doing this test was that when I released the throttle about a second to five seconds later I would hear a click. I did this several times and always got it. I removed the TPS and used a large screw driver to take the place of the throttle shaft and saw that the TPS was hanging at about 1/4 to 1/3 open. Sometimes it would click closed after a few seconds and sometimes it wouldn't.

I replaced the TPS and the voltages are correct now and that along with the smooth movement of the sensor the above problem seems to have been corrected. We'll see after driving for a while in the Missouri winter.

Thanks to all who contribute to the forum. I'm in your debt.

Chris

ETA: This is a 2002 Expedition XLT with about 120,000 miles and the 5.4L motor.

Last edited by ResJudicata; 01-01-2010 at 02:03 PM. Reason: Additional info
Reply With Quote
  #2 (permalink)  
Old 01-05-2010, 03:07 PM
ResJudicata ResJudicata is offline
Freshman User
 
Join Date: Feb 2007
Posts: 31
ResJudicata is starting off with a positive reputation.
Update

FYI, I have been driving my truck since Friday. The idle is smoother than before. It used to idle about 650 rpm according to the dash tach. Now it is at about 750 rpm and smoother feeling and sounding. Acceleration is about the same.

But, the most interesting thing is that the transmission is shifting better. It used to feel like it was searching at times and the overdrive shuddered when it engaged. Now, I haven't noticed any searching, it shifts nice a smooth into each gear and even into overdrive.

The computer must use input from the TPS for regulating the shifting of the transmission in addition to just the mixture. I'm surprised by this but I guess I shouldn't be.

Well, knock on wood but I think this has been a very lucky and cheap fix. The TPS was $39.99 from O'reilly Auto and very easy to install. Apparently it has been a problem for at least a year but has never shown up as a CEL until last week.

Chris

ETA: And, no reoccurance of the earlier problems in the very cold weather. It has been in the teens or below since last week and no issues.

Last edited by ResJudicata; 01-05-2010 at 03:09 PM. Reason: Additional info
Reply With Quote
  #3 (permalink)  
Old 01-05-2010, 03:37 PM
alloro alloro is offline
Post Fiend
 
Join Date: Apr 2008
Location: 0,0,1
Posts: 9,131
alloro is a name known to allalloro is a name known to allalloro is a name known to allalloro is a name known to allalloro is a name known to allalloro is a name known to all
Quote:
Originally Posted by ResJudicata View Post
The computer must use input from the TPS for regulating the shifting of the transmission in addition to just the mixture. I'm surprised by this but I guess I shouldn't be.
Actually the computer uses the TPS, MAP and VSS as it's primary inputs for determining shift points. The atmospheric pressure, throttle position and vehicle speed are all major factors.
__________________
To thank someone, click the left red "Add to Reputation" button
right of the word "permalink" top right of the poster's message.
Reply With Quote
  #4 (permalink)  
Old 01-06-2010, 10:42 AM
ResJudicata ResJudicata is offline
Freshman User
 
Join Date: Feb 2007
Posts: 31
ResJudicata is starting off with a positive reputation.
Quote:
Originally Posted by alloro View Post
Actually the computer uses the TPS, MAP and VSS as it's primary inputs for determining shift points. The atmospheric pressure, throttle position and vehicle speed are all major factors.
Thanks for the info. It's good to know that I'm not crazy. I haven't done much diagnosis on modern fuel injection systems. In the past it was with older systems that didn't cover so many parts of the vehicle.

Chris
Reply With Quote
  #5 (permalink)  
Old 01-19-2010, 03:58 PM
supersantay supersantay is offline
New User
 
Join Date: Jan 2010
Posts: 1
supersantay is starting off with a positive reputation.
Chris - your post here is outstanding... I have been experiencing very similar issues to what you describe - High Idle, can't shift out of 1st gear... I never received a CEL on mine and was getting nervous about what my issue might be.. I used a code reader from my friend and checked it anyway and low and behold the P1121 was there. That is what helped me find your post.

I also have an '02 Expedition with the 5.4L. I will do further checks and hope this turns out to be the same easy fix you experienced!

Again Thanks!
Reply With Quote
  #6 (permalink)  
Old 01-19-2010, 04:02 PM
ResJudicata ResJudicata is offline
Freshman User
 
Join Date: Feb 2007
Posts: 31
ResJudicata is starting off with a positive reputation.
Do a search on here for how to check the TPS using a volt meter. Also, even if the voltage reading are right it might be worth pulling the TPS off and checking for smooth movement.

Good luck.

Chris
Reply With Quote
  #7 (permalink)  
Old 02-28-2012, 06:27 PM
bzcomputers bzcomputers is offline
New User
 
Join Date: Feb 2012
Posts: 1
bzcomputers is starting off with a positive reputation.
Quote:
Originally Posted by ResJudicata View Post
ETA: This is a 2002 Expedition XLT with about 120,000 miles and the 5.4L motor.
Thanks for posting this. I was having the same problem except my check engine light came on immediately. I have a nearly identical vehicle and mileage as original poster.

2002 Expedition EB with 5.4L at 126,000 miles - replaced the TPS and all is well again. About $20 and 20 min.
Reply With Quote
  #8 (permalink)  
Old 02-28-2012, 07:21 PM
ResJudicata ResJudicata is offline
Freshman User
 
Join Date: Feb 2007
Posts: 31
ResJudicata is starting off with a positive reputation.
It's good to know that I posted something that is actually helpful for folks.

Unfortunately, (or fortunately depending how you look at it) I just traded my Expedition in on a new Focus. The truck was still in very nice shape so I got good money out of it. But, it was time to do some expensive repairs like ball joints and the directional valve in the heating system. Plus the fuel bill was killing me with the amount of miles I drive now.

So, I picked up a Focus Titanium that I can fill up for $30.

At least it's still a Ford.

Chris
Reply With Quote
Old 02-28-2012, 07:21 PM
Reply

Go Back   Ford Truck Enthusiasts Forums > Newer Light Duty Trucks > Expedition & Navigator

Tags
1121, 1997, 2002, code, dtc, expedition, f150, ford, p1121, pl, position, sensor, specs, switch, throttle

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On
Forum Jump



All times are GMT -5. The time now is 06:34 AM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup