Go Back   F150online Forums > Powertrain & Mechanical > V8 Engines
Sign in using an external account
Register Forgot Password?
Register Photos Vin Decoder FAQ Members Search Today's Posts Mark Forums Read Vendor DirectoryGarage

Welcome to F150Online Forums!
Welcome to F150Online.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 F150Online Forums community today!





Reply
 
 
 
 
Thread Tools Search this Thread Display Modes
  #1  
Old 12-28-2004, 09:01 PM
Junior Member
Garage is empty, add now
 
Join Date: Dec 2004
Vehicle: 98 ford f150
Posts: 8
98 f150 iac code 1506

Was hope for some help...
I have a 1998 Ford F150...4.6 motor
I cleaned the throttle/butterfly area with intake cleaner...then went to drive the truck..The idle was around 1050 in park...had a code ..po1506 ..idle overspeed fault...I then replaced the IAC and proceeded the drive the truck so the engine will relearn the idle process...the check engine light did not come back on but the idle still seemed a bit to high...I'm I doing something wrong here?????? I NEVER had a problem like this just from cleaning the throttle plate!!!!....does anyone have any ideas?????

PLEASE help..if possible..
Tom
Reply With Quote
  #2  
Old 12-28-2004, 09:17 PM
Senior Member
Garage is empty, add now
 
Join Date: Sep 2003
Location: Aggieland, TX
Vehicle: 1997 Ford F150 4x4
Posts: 3,053
how high does it idle now?

how did you clean the intake? Did you remove it and clean it?
__________________

'02 F250 Lariat CrewCab, 4x4, 7.3L PSD

My Gallery
Reply With Quote
  #3  
Old 12-28-2004, 09:29 PM
Junior Member
Garage is empty, add now
 
Join Date: Dec 2004
Vehicle: 98 ford f150
Posts: 8
98 f150 IAC code 1506

hi John..
thanks for your reply!!!
I've been going crazy with this problem...

I took a tiny bit of intake cleaner and a brush...cleaned the butterfly area while the throttle was on the car...then the code came in and the idle was higher...

I last drove the truck this afternoon...the idle in park appeared to be about 1000...

I hoping the relearn process just needs to be done..I diden't hear back from the owner so I guess No news is good news...but I would like to find out info for my own knowledge
Reply With Quote
  #4  
Old 12-28-2004, 09:41 PM
Junior Member
Garage is empty, add now
 
Join Date: Dec 2004
Vehicle: 98 ford f150
Posts: 8
98 f150 IAC code 1506

just to add a bit of info...

The truck ran pretty decent when it came in...I noticed the throttle plate was carboned up...that's when I decided the clean it out...from there all the problems started...check engine light on...code 1506 IAC overspeed fault...relaced the valve..cleared the codes the drove the truck however I did not disconnect the battery...WOULD THE COMPUTER STILL PICK UP THE READINGS OF THE OLD VALVE???? ....I then disconnected the battery and drove it again...the check engine light did not come on but the idle was still a bit high...about 1050+ in Park 850-9 in drive...

Ant Ideas?????
Reply With Quote
  #5  
Old 12-28-2004, 10:34 PM
Senior Member
Garage is empty, add now
 
Join Date: Sep 2003
Location: Aggieland, TX
Vehicle: 1997 Ford F150 4x4
Posts: 3,053
well, the idle is definitely too high...it should be under 800 when warm.

I would say try disconnecting the battery again (remove the neg battery cable, turn on the headlights for ~10 minutes), but make sure you let the truck idle for about 10 inutes when you reconnect the battery before you drive it.

Other than that Im not real sure (and I kind ofdoubt this will fix your problem but its worth a shot).
Reply With Quote
  #6  
Old 12-29-2004, 07:33 AM
Junior Member
Garage is empty, add now
 
Join Date: Dec 2004
Vehicle: 98 ford f150
Posts: 8
98 f150 IAC code 1506

just heard info regarding this truck....
the idle has seemed to come down a bit...however the check engine light has come back on...I will have to check it on the computer again to see if the same code has returned...

I have be an auto mechanic for 16 years and have NEVER come accross such a situation!!! This one seems to baffle everyone I speak with....

Thanks for your input!!!!! At this point I'll try anything!!

More to come....
Reply With Quote
  #7  
Old 12-29-2004, 04:35 PM
Senior Member
Garage is empty, add now
 
Join Date: May 2001
Location: Maryland
Vehicle: 1999 Ford F150
Posts: 1,080
Send a message via AIM to hcmq Send a message via Yahoo to hcmq
My guess is that you messed up the positioning of the throttle plate when you cleaned it. Did you just use your fingers to hold it open?

Also, did you run the engine while cleaning it?

The IAC usually causes a low idle concern.

Do what johngs says and disco the neg cable then turn the lights on. after 5-8 min turn the lights off then recon the neg batt cable start truck and don't touch the gas when starting and let idle for 8-10 min then you must drive it for atleast 20 min after that.

remeber codes are for where to start a diagnosis not for what sensor to replace.

good luck-
Reply With Quote
  #8  
Old 12-29-2004, 06:25 PM
Junior Member
Garage is empty, add now
 
Join Date: Dec 2004
Vehicle: 98 ford f150
Posts: 8
98 f150 IAC code 1506

Thanks for all the info!!!

I'll be looking at the truck again the end of the week...
I'll try disconnecting the battery/headlights on..etc...

Do you think It is possible that carbon was disturbed down lower in the intake????? causing a problem...

Tom
Reply With Quote
  #9  
Old 12-29-2004, 06:30 PM
Junior Member
Garage is empty, add now
 
Join Date: Dec 2004
Vehicle: 98 ford f150
Posts: 8
98 f150 IAC code 1506

had the engine OFF while cleaning...
I used a soft brush to lightly clean the surface..
and I held it open just by holding the linkage..never had my fingers anywhere near the plate area...

these seem like all logical explanations...I'll look into each of them..
Thanks!!!
Reply With Quote
  #10  
Old 12-29-2004, 06:32 PM
Senior Member
Garage is empty, add now
 
Join Date: Aug 2002
Location: Starkville Mississippi
Vehicle: 1998 Ford F-150/ 4.6
Posts: 1,895
98 4.6 73,000 miles:

i took my IAC/throttle body/EGR valve completely off this last weekend and cleaned both completely out. Lots of carbon build up. After I got them all back on and a new battery in my truck, my truck idled high too for about 50 miles or so, then it settled back down, but still runs a little faster and "peppier" then before i did the cleaning
Im thinking that if you unhook your negative terminal, turn on the headlights for a while, then turn them off and re-connect your battery, your truck will settle back down. You might also consider doing this throttle body cleaning to your truck,it's amazing how much better your truck will run after all the carbon is cleaned out.

If interested, check out my thread on "rough idle" on page 2 in the Engines forum.
__________________

1998 F-150. 4.6 auto 3.55 Straight Pipes.
1953 Chevy 3100 half ton all stock. Cherry Red.
Keep on pickin'
Reply With Quote
Old 12-29-2004, 06:32 PM


 
 
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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 Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


All times are GMT -4. The time now is 09:43 AM.


 
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
Contact Us Advertising Privacy Statement Terms of Service Jobs Forum Text Archives
Emails & Contact Details