1999 4.6 idle problem
Thread Starter
|
New User
Joined: Dec 2011
Posts: 6
Likes: 0
From: northwestern , PA.
1999 4.6 idle problem
Hey guys i have a 1999 f-150 4x4 4.6 5spd manual 180,000 miles on the
clock. My question is, when coming to a stop i push the clutch in an the
idle hangs at about twice what it should be until i come to a complete
stop then it drops to normal. It's not like somethings sticking cause it
will stay at the high idle as long as were rolling but as soon as the wheels
stop turning it drops down, any ideas?
thanks!
clock. My question is, when coming to a stop i push the clutch in an the
idle hangs at about twice what it should be until i come to a complete
stop then it drops to normal. It's not like somethings sticking cause it
will stay at the high idle as long as were rolling but as soon as the wheels
stop turning it drops down, any ideas?
thanks!
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
I've seen this issue reported a number of times across all Ford lines.
Normally when deceleration occurs the IACs closes down to just enough to keep the motor from stalling and turns fuel injection off for the short period of time.
The way the computer knows what to do is by the TPS being near shutdown and the speed sensor output slowing.
The speed sensing is part of a circuit that goes through the clutch pedal switching to the PCM..
You say the idle hangs up when the clutch is depressed suggests the speed circuit is disrupting the normal decell action.
I can't tell you just what to do but this is the way it's supposed to work.
If there is an open or short at some point, the normal action will be upset leaving the IAC open and fuel still on to run the motor at high RPM idle speeds..
Good luck.
Normally when deceleration occurs the IACs closes down to just enough to keep the motor from stalling and turns fuel injection off for the short period of time.
The way the computer knows what to do is by the TPS being near shutdown and the speed sensor output slowing.
The speed sensing is part of a circuit that goes through the clutch pedal switching to the PCM..
You say the idle hangs up when the clutch is depressed suggests the speed circuit is disrupting the normal decell action.
I can't tell you just what to do but this is the way it's supposed to work.
If there is an open or short at some point, the normal action will be upset leaving the IAC open and fuel still on to run the motor at high RPM idle speeds..
Good luck.
Thread Starter
|
New User
Joined: Dec 2011
Posts: 6
Likes: 0
From: northwestern , PA.
46 idle problem
Thanks Bluegrass7, been finding alot of corrosion on the wiring in this truck. This old girl musta been through afew salty PA. winters. I'll start
cleaning connections an watch for a parts truck. Thanks again for the
help.
cleaning connections an watch for a parts truck. Thanks again for the
help.
Thread
Thread Starter
Forum
Replies
Last Post
Joey in IN
1997 - 2003 F150
1
Dec 8, 2007 07:45 AM
