Idle very high
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Mountain Pass
Joined: May 2020
Posts: 227
Likes: 3
From: Lehi, Utah
Idle very high
I made a few small changes to my 84 F150 Inline 6 yesterday. I swapped out a new negative battery cable. The old cable had two wires spliced in right before the terminal. One connected directly to a ground point on the firewall. It seemed a little weird to have a ground connected to another ground. When I installed the new cable, I didn't splice in the two wires. I'm not sure what the other wire connects to. It looks like it runs into the driver side firewall with a bunch of other wires. The electrical systems seemed fine without them, so I thought I'd try it out. I also replaced a vacuum line that was connected to the carb. It was a capped bit of hose, not connected to anything. I replaced it with a cap, just trying to clear some mess out of the engine compartment.
I took the truck out last night, and it was idling really high. I didn't really notice at first, because it usually idles high while it warms up. But it didn't slow down, and it maybe got worse as I drove. It was idling so fast, that I would put it into gear and let the clutch partly out, to calm the engine down, when I was at a stop.
Could removing these wires be related to my idle issue?
I took the truck out last night, and it was idling really high. I didn't really notice at first, because it usually idles high while it warms up. But it didn't slow down, and it maybe got worse as I drove. It was idling so fast, that I would put it into gear and let the clutch partly out, to calm the engine down, when I was at a stop.
Could removing these wires be related to my idle issue?
Thread Starter
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Mountain Pass
Joined: May 2020
Posts: 227
Likes: 3
From: Lehi, Utah
I noticed that the choke doesn't seem to be closing as the engine warms up. When I push it in the idle dies down. Is the choke behavior governed by the ECM?
FTE Legend
Joined: Nov 2015
Posts: 30,912
Likes: 4,123
From: Angier, NC
Being a 84 300 six motor it would be a feed back system and that carb is controlled by a computer.
That plug looks to be over by the battery as I think I see the ALT with 2 belts below.
If so I think I have seen it posted the computer ground is over in that area.
As a test run a jumper wire from battery ground to that wire like if it was hooked up and see what happens.
BTW when the motor warms up the choke should open not close.
If you were closing it and the idle slowed down that could be a sign of a vacuum leak.
Maybe you knocked off a vacuum line or 2?
Dave ----
That plug looks to be over by the battery as I think I see the ALT with 2 belts below.
If so I think I have seen it posted the computer ground is over in that area.
As a test run a jumper wire from battery ground to that wire like if it was hooked up and see what happens.
BTW when the motor warms up the choke should open not close.
If you were closing it and the idle slowed down that could be a sign of a vacuum leak.
Maybe you knocked off a vacuum line or 2?
Dave ----
FTE Legend
Joined: Nov 2015
Posts: 30,912
Likes: 4,123
From: Angier, NC
Now some of them systems have gone bad, sensor go bad and can no longer get making it run bad, so it has been converted back to the DSII IGN system before feed back so the computer is not needed.
Both of you may want to follow that harness back and if it goes to a box, aka computer, then you will know what that wire was for, ground for the computer.
Dave ----
Cross-Country
Joined: Mar 2020
Posts: 84
Likes: 2
If yours has a 300 six then it also had the feed back carb system.
Now some of them systems have gone bad, sensor go bad and can no longer get making it run bad, so it has been converted back to the DSII IGN system before feed back so the computer is not needed.
Both of you may want to follow that harness back and if it goes to a box, aka computer, then you will know what that wire was for, ground for the computer.
Dave ----
Now some of them systems have gone bad, sensor go bad and can no longer get making it run bad, so it has been converted back to the DSII IGN system before feed back so the computer is not needed.
Both of you may want to follow that harness back and if it goes to a box, aka computer, then you will know what that wire was for, ground for the computer.
Dave ----
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Lead Driver
Joined: Jul 2009
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From: Sheffield, AL
Originally Posted by xenophone;19401717
I noticed that the choke doesn't seem to be closing as the engine warms up. When I push it in the idle dies down. Is the choke behavior governed by the ECM?
[img
I noticed that the choke doesn't seem to be closing as the engine warms up. When I push it in the idle dies down. Is the choke behavior governed by the ECM?
[img
https://cimg4.ibsrv.net/gimg/www.ford-trucks.com-vbulletin/960x1280/neg_cable1_9a1ef24aa0c58002ddf669214ec1493fbabb7d2 3.jpg
The high idle speed is likely caused by a vacuum leak. Check to see if any other hoses or rubber caps were disturbed while you replaced the one hose.
Read this link: https://www.ford-trucks.com/forums/1...expensive.html
Last edited by 1986F150six; Jul 27, 2020 at 11:25 AM. Reason: Added link.
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Cross-Country
Joined: Mar 2020
Posts: 84
Likes: 2
If yours has a 300 six then it also had the feed back carb system.
Now some of them systems have gone bad, sensor go bad and can no longer get making it run bad, so it has been converted back to the DSII IGN system before feed back so the computer is not needed.
Both of you may want to follow that harness back and if it goes to a box, aka computer, then you will know what that wire was for, ground for the computer.
Dave ----
Now some of them systems have gone bad, sensor go bad and can no longer get making it run bad, so it has been converted back to the DSII IGN system before feed back so the computer is not needed.
Both of you may want to follow that harness back and if it goes to a box, aka computer, then you will know what that wire was for, ground for the computer.
Dave ----
it’s a ground my truck idled down once it was grounded and i can now get codes off my code reader.. Before it would never connect now just trying to fix the stalling (happened after I grounded the wire) and the popping which happened before!
Thread Starter
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Mountain Pass
Joined: May 2020
Posts: 227
Likes: 3
From: Lehi, Utah
If yours has a 300 six then it also had the feed back carb system.
Now some of them systems have gone bad, sensor go bad and can no longer get making it run bad, so it has been converted back to the DSII IGN system before feed back so the computer is not needed.
Both of you may want to follow that harness back and if it goes to a box, aka computer, then you will know what that wire was for, ground for the computer.
Dave ----
Now some of them systems have gone bad, sensor go bad and can no longer get making it run bad, so it has been converted back to the DSII IGN system before feed back so the computer is not needed.
Both of you may want to follow that harness back and if it goes to a box, aka computer, then you will know what that wire was for, ground for the computer.
Dave ----
Thread Starter
|
Mountain Pass
Joined: May 2020
Posts: 227
Likes: 3
From: Lehi, Utah
Being a 84 300 six motor it would be a feed back system and that carb is controlled by a computer.
That plug looks to be over by the battery as I think I see the ALT with 2 belts below.
If so I think I have seen it posted the computer ground is over in that area.
As a test run a jumper wire from battery ground to that wire like if it was hooked up and see what happens.
BTW when the motor warms up the choke should open not close.
If you were closing it and the idle slowed down that could be a sign of a vacuum leak.
Maybe you knocked off a vacuum line or 2?
Dave ----
That plug looks to be over by the battery as I think I see the ALT with 2 belts below.
If so I think I have seen it posted the computer ground is over in that area.
As a test run a jumper wire from battery ground to that wire like if it was hooked up and see what happens.
BTW when the motor warms up the choke should open not close.
If you were closing it and the idle slowed down that could be a sign of a vacuum leak.
Maybe you knocked off a vacuum line or 2?
Dave ----
Thread Starter
|
Mountain Pass
Joined: May 2020
Posts: 227
Likes: 3
From: Lehi, Utah
The choke is controlled by heat. There should be an electrical wire going to the black choke housing cap as well as a metal tube which supplies heated air from the exhaust manifold to the choke housing.
The high idle speed is likely caused by a vacuum leak. Check to see if any other hoses or rubber caps were disturbed while you replaced the one hose.
Read this link: https://www.ford-trucks.com/forums/1...expensive.html
The high idle speed is likely caused by a vacuum leak. Check to see if any other hoses or rubber caps were disturbed while you replaced the one hose.
Read this link: https://www.ford-trucks.com/forums/1...expensive.html
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
That may not happen with the computer stuff on there. Ford had a few other engines they did this to, including my 2.8 v6 in my Bronco II. I got rid of it and it runs a lot better.
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
There are a bunch of threads on here about it. But they are all titled with something else most likely. Most of them are "taking emissions off my engine" or "my engine won't run correctly" etc. Then we find out they have a 300 six with all the vacuum lines unplugged and then the only choice they have is to convert it over.
The main piece you need is the distributor. You can get a distributor for a very early 80's 300 six, and then get the Ford ignition module to with it and the wiring. Or they do make retro fit one wire aftermarket distributors with a HEI coil and ignition module already mounted.
The distributor is the biggest piece of the puzzle, and then you can decide on what older style carb you want to run. I am still running the computer carb, it does fine on my engine and I still got rid of all the wires and vacuum lines and the computer also. But you may need a new carb anyway if yours is wore out. There are several places including Amazon where you can get a new carb.
The main piece you need is the distributor. You can get a distributor for a very early 80's 300 six, and then get the Ford ignition module to with it and the wiring. Or they do make retro fit one wire aftermarket distributors with a HEI coil and ignition module already mounted.
The distributor is the biggest piece of the puzzle, and then you can decide on what older style carb you want to run. I am still running the computer carb, it does fine on my engine and I still got rid of all the wires and vacuum lines and the computer also. But you may need a new carb anyway if yours is wore out. There are several places including Amazon where you can get a new carb.