Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1987 - 1996 F150 & Larger F-Series Trucks
Sign in using an external account
Register Forgot Password?


1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

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  
Old 11-01-2011, 09:24 PM
Scott Stewart Scott Stewart is offline
New User
 
Join Date: Sep 2011
Posts: 15
Scott Stewart is starting off with a positive reputation.
1994 ford F150 XLT 5.0 high idle - SOLVED!

My 1994 ford F150 XLT 5.0 has a high Idle problem that just recently showed up. The truck had been acting just fine until one day while hauling off limbs – the idle just jumped up. This is a standard shift truck – so the high idle was very noticeable during the shifts (sorry I don’t Have a tach so I don’t know the rpms) but it defiantly wasn’t racing rpms – by very high for an idle. When the ignition is turned off the and the truck restarted – everything is normal – the idle is where it is supposed to be – until I step on the gas pedal and raise the rpms, the high idle appears (doesn’t matter whether the engine is hot or cold). Sometimes it happens immediately and then sometimes it appears after a few shifts. Even it has disappeared at times when I am driving the truck only to reappear later. Got any Ideas as to the cause? I'm really lovin' this old truck and I want to keep at it's best

Click the image to open in full size.
Reply With Quote
  #2  
Old 11-01-2011, 11:35 PM
lmd91343's Avatar
lmd91343 lmd91343 is offline
Senior User
 
Join Date: Nov 2007
Location: Los Angeles, CA
Posts: 435
lmd91343 is gaining momentum as a positive member of FTE.
Check for a vacuum leak. SD motors will idle higher with a leak. Check around the upper and lower plenum interface. Mine did the same as yours. I've had to replace mine twice.

The cpu increases the gas volume because of the change in the MAP reading which has changed by the increased airflow from the leak.

Yes, my first leak was intermittent between plenum passages..
__________________
-Lance
1989 f150 302 Lariat
MAF conversion; MSD 6a; MSD Blaster 2 coil; 3G alternator; insulated 460 intake tube; sound proofed; 3rd brake light; custom leather seats; low fuel light; instant mpg gauge; reupholstered door panels; tach install; "A" pillar gauges; Truxedo Lo-Pro color keyed to paint; back up monitor in r v mirror
2009 Escape Hybrid 2.5L 35.5 MPG in town!
Reply With Quote
  #3  
Old 11-02-2011, 08:00 AM
Scott Stewart Scott Stewart is offline
New User
 
Join Date: Sep 2011
Posts: 15
Scott Stewart is starting off with a positive reputation.
Will check today - going to get some carb cleaner to check for Vacuum leaks. I'll let you guys know what I find
Reply With Quote
  #4  
Old 11-02-2011, 08:10 AM
OverReved OverReved is offline
Senior User
 
Join Date: Jan 2007
Posts: 191
OverReved is starting off with a positive reputation.
If you haven't left for the parts store yet, while you are there, ask them to check for any trouble codes. Most parts places will have a code reader. Also, the next time the idle jumps up, pop the hood and check to see if the throttle has returned all the way. You will need to remove the plastic cover first. Mine did something similar and I just needed to clean and lubricate the external linkage.
Reply With Quote
  #5  
Old 11-02-2011, 10:09 AM
rla2005's Avatar
rla2005 rla2005 is offline
Post Fiend
 
Join Date: Oct 2005
Location: Illinois
Posts: 8,040
rla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to behold
Quote:
Originally Posted by Scott Stewart View Post
My 1994 ford F150 XLT 5.0 has a high Idle problem that just recently showed up. The truck had been acting just fine until one day while hauling off limbs – the idle just jumped up. This is a standard shift truck – so the high idle was very noticeable during the shifts (sorry I don’t Have a tach so I don’t know the rpms) but it defiantly wasn’t racing rpms – by very high for an idle. When the ignition is turned off the and the truck restarted – everything is normal – the idle is where it is supposed to be – until I step on the gas pedal and raise the rpms, the high idle appears (doesn’t matter whether the engine is hot or cold). Sometimes it happens immediately and then sometimes it appears after a few shifts. Even it has disappeared at times when I am driving the truck only to reappear later. Got any Ideas as to the cause? I'm really lovin' this old truck and I want to keep at it's best

Click the image to open in full size.
That does not sound like a vacuum leak to me. Classic symptom of a faulty TPS or connector to the TPS.

I found the connector to the TPS on my truck was full of green corrosion cuasing the same type of issue. Scraped it off, sprayed a little contact cleaner on it, then reassembled. Verified the TPS output signal was linear from closed to open throttle with a DVM. Still working good to this day.

It would be a good idea to make sure the throttle is closing completely as well. Sometimes a sticky throttle cable or the throttle body bushing itself can keep the throttle partially open from time to time.
Reply With Quote
  #6  
Old 11-02-2011, 05:06 PM
Scott Stewart Scott Stewart is offline
New User
 
Join Date: Sep 2011
Posts: 15
Scott Stewart is starting off with a positive reputation.
Well folks - Here is the offender - Notice the upper wire end - it is missing some of the insulation! Obviously not making a good connection. Time to replace the TPS. Unfortunately this is the model in which you have to remove the whole throttle body to get to the TPS. When I go everything off - the backside of the tubes and the throttle plates where coated with carbon - so I gave it a cleaning as well. I also found some oil reside that had crept into the TPS (maybe another reason for the failure). I installed the new TPS and adjusted it to 1.o volts as per manual. Then bolted everything back up and cranked the engine - normal idle. Took the truck out for a test drive - no problem.


Click the image to open in full size.

Thanks for the help
Reply With Quote
  #7  
Old 11-02-2011, 05:37 PM
rla2005's Avatar
rla2005 rla2005 is offline
Post Fiend
 
Join Date: Oct 2005
Location: Illinois
Posts: 8,040
rla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to beholdrla2005 is a splendid one to behold
Thanks for reporting back with the resolution!
Reply With Quote
Old 11-02-2011, 05:37 PM
 
 
 
Reply

Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1987 - 1996 F150 & Larger F-Series Trucks

Tags
1994, 1996, 49, 50, 87, 94, 96, engine, f150, ford, good, high, idle, idleing, oil, problem, start, xlt

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
1994 ford f510 shifting "hard" lets see what you think 1975 390 1987 - 1996 F150 & Larger F-Series Trucks 2 04-06-2012 11:24 PM
High Idle Problem forddude2134 1987 - 1996 F150 & Larger F-Series Trucks 1 12-02-2009 07:45 PM
1994 f150 XLT shifting problems brett12396f150 1987 - 1996 F150 & Larger F-Series Trucks 7 10-30-2009 12:22 PM
High idle after extended freeway driving wilevel2 1987 - 1996 F150 & Larger F-Series Trucks 8 07-07-2009 04:24 PM
My 89 F150 5.0L just quits. petersonl 1987 - 1996 F150 & Larger F-Series Trucks 7 06-14-2009 01:54 PM



All times are GMT -5. The time now is 03:57 AM.


Powered by vBulletin® Version 3.8.7 AC1
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. Ford® is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup