EFI 460 Idle Speed Question - 460 Ford Forum
Engine Tech A place to discuss all 385-series engine tech and theory.

User Tag List

 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 9 (permalink) Old 03-20-2007, 07:56 PM Thread Starter
Member
 
97_460's Avatar
 
Join Date: Mar 2007
Location: Iowa
Posts: 55
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
EFI 460 Idle Speed Question

I recently bought a '97 F350 with the 460. The truck has 115k miles on it and the engine seems to run great. The only issue (other that a broken manifold stud) is that it seems to idle too high. Fast idle is around 1200 rpm, but it only drops down to 1000 rpm when warm.

I performed a quick tune-up on it which was limited to plugs, wires, cap & rotor, new filters, and cleaning the throttle body. None of this has seemed to help.

Any experience or advice on this subject would be appreciated.

Thanks

1979 F150 4x4 SWB, 460, C6
1988 F250 4x4, 460, C6
1989 F350 4x4, 472 swap in progress, C6
97_460 is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 03-20-2007, 08:13 PM
PBR
Senior Member
 
Join Date: Jan 2007
Location: Mesa, AZ
Posts: 313
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Send a message via AIM to PBR
Try cleaning the IAC, it should be on the side of the throttlebody and look like this:



I know this is a Mustang picture but it'll real close to this.

All you need to do is take it off and spray the heck out of it with carb cleaner until all the crap quits dumping out of it and the movement is free and easy.

-Paul
PBR is offline  
post #3 of 9 (permalink) Old 03-20-2007, 09:03 PM Thread Starter
Member
 
97_460's Avatar
 
Join Date: Mar 2007
Location: Iowa
Posts: 55
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
I will look for the IAC and give it a try.

Thanks

1979 F150 4x4 SWB, 460, C6
1988 F250 4x4, 460, C6
1989 F350 4x4, 472 swap in progress, C6
97_460 is offline  
post #4 of 9 (permalink) Old 03-20-2007, 10:05 PM
Junior Member
 
Join Date: Mar 2007
Location: Haslet Texas
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
See if there is a code.

Good source for Ford EFI is http://fordfuelinjection.com/. They have stuff that will help you. I have learned a lot about EFI from that site. good luck

64 F100 short bed with mild 460 (starting conversion to FI Yes I am drilling my own FI bungs (thanks to BigBlockRanger)).
pfm-64f100 is offline  
post #5 of 9 (permalink) Old 03-21-2007, 09:15 AM
Senior Member
 
PatFromJersey's Avatar
 
Join Date: Jan 2006
Location: Lakewood, NJ
Posts: 1,117
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Send a message via AIM to PatFromJersey Send a message via Yahoo to PatFromJersey
Double check for any vacuum leaks too. That'll bump it up a tad. I'm taking in all this 460 EFI stuff too, since I just bought a 97 F250 Super Duty. 8)

New project coming... 1932 Ford 5 Window Coupe 521/C6
PatFromJersey is offline  
post #6 of 9 (permalink) Old 03-21-2007, 10:16 AM
Senior Member
 
Join Date: Jan 2006
Location: Patricia, Alberta, Canada
Posts: 476
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
My 1990 has done the same thing since my it was new, and the dealership could never fix it back when it was on warranty. I just gave up and have been putting up with it. It doesn't set a code, and otherwise runs fine, so I just ignore it, although it is annoying at times...

668. The neighbour of the beast.
John I. is offline  
post #7 of 9 (permalink) Old 03-21-2007, 10:43 AM Thread Starter
Member
 
97_460's Avatar
 
Join Date: Mar 2007
Location: Iowa
Posts: 55
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Quote:
Originally Posted by John I.
My 1990 has done the same thing since my it was new, and the dealership could never fix it back when it was on warranty. I just gave up and have been putting up with it. It doesn't set a code, and otherwise runs fine, so I just ignore it, although it is annoying at times...
I was wondering if this could be normal... the truck runs great. I'm going to check the IAC this weekend, and if it doesn't help, I'll just quit worrying about it.

Thanks

1979 F150 4x4 SWB, 460, C6
1988 F250 4x4, 460, C6
1989 F350 4x4, 472 swap in progress, C6
97_460 is offline  
post #8 of 9 (permalink) Old 03-25-2007, 05:45 PM
Senior Member
 
Danny Cabral's Avatar
 
Join Date: Jan 2006
Location: Connecticut
Posts: 2,614
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
 
TSB-91-25-7 idle air by-pass service kit

You might find this thread interesting:
http://www.ford-trucks.com/forums/33...urge-prob.html (My post is the last one on page 2.)

May God's Grace Bless You

'78 BRONCO: 508" stroker, TFS heads, Dominator MPFI & DIS, cold air induction, dual 3" exhaust/Magnaflow mufflers, 100HP progressive dry direct-port NOS, A/C, Lentech Strip Terminator wide-ratio AOD, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, custom traction bars, 4" lift, 35" mud tires
Danny Cabral is offline  
post #9 of 9 (permalink) Old 03-25-2007, 11:12 PM
Senior Member
 
Join Date: Jan 2006
Location: San Jose, CA
Posts: 2,185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Idle speed issues

The throttle position sensor plays a role in older ford EFI systems, but in the case of yours...it will not, so don't adjust it.

The EEC looks at the position of the TPS at key-on and says "that's closed". In the earlier EECs, the voltage out of the TPS could effect idle quality.

A stuck IAC, incorrect base timing, misadjusted throttle plate, vacuum leak, or rich condition can all cause elevated idle. It is NOT normal.

That said, check your idle speed with a scan tool, not the factory tach. The factory tachs are usually VERY far off.

After that, I'd start looking for air leaks. Any hole between the MAF and the intake ports on the heads...even the size of a pencil lead...can do this.

Is your check engine light on? If so, what's the code?

Next, has anyone messed with base spark? Does this truck still have a TFI Ford distributor?

What do your long term fuel trims look like after 5 minutes at idle on a 160+deg F engine? If you don't have an OBD-II scan tool with datastream, you need one.

Let me know,

Byron

www.RaceSystems.com
Home of Project Ludicrous Speed
ByronRACE is offline  
Sponsored Links
Advertisement
 
Reply
Gear in this thread - Powered by O'Reilly Auto Parts

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the 460 Ford Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome