throttle body question
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
sounds like the tps is either bad or needs adjusted. www.fordfuelinjection.com has a writeup as does a haynes manual. you cant just throw a tps on there and figure it a-ok.
did the throttle body idle screw get turned at some point? if so this could be a problem and could be why your having issues with the rpm. if i recall you must unhook the IAC and then turn idle screw till it idles at 600 rpms and then plug the iac back in. Grey can confirm this process i am sure. im also wondering if the solvant that was used to clean the TB removed the coating that was on the throttle body which would create a vacum leak around the butterflys
did the throttle body idle screw get turned at some point? if so this could be a problem and could be why your having issues with the rpm. if i recall you must unhook the IAC and then turn idle screw till it idles at 600 rpms and then plug the iac back in. Grey can confirm this process i am sure. im also wondering if the solvant that was used to clean the TB removed the coating that was on the throttle body which would create a vacum leak around the butterflys
Posting Guru
Joined: Apr 2006
Posts: 1,274
Likes: 1
Hey Greystreak,
Do you remember this
"Then stay with the EFI! The guys understood you perfectly... the EFI IS the simple way! Besides that, if you go through all the obnoxious swapping to get BACK to a carburetor, you take the EEC-IV computer out of the mix which takes the ability to troubleshoot WITHOUT chasing ghosts and replacing things that MIGHT be bad completely out of your hands. You go back to guessing and hoping you guessed right.
Sounds like you guys are chasing ghosts and doing alot of guessing. LOL
Do you remember this
"Then stay with the EFI! The guys understood you perfectly... the EFI IS the simple way! Besides that, if you go through all the obnoxious swapping to get BACK to a carburetor, you take the EEC-IV computer out of the mix which takes the ability to troubleshoot WITHOUT chasing ghosts and replacing things that MIGHT be bad completely out of your hands. You go back to guessing and hoping you guessed right.
Sounds like you guys are chasing ghosts and doing alot of guessing. LOL
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 328
Likes: 0
i have 2 spare IAC motors but not at my house. if i get it in running condition enough to drive i will get the others and a gasket.
for now, i jerry rigged the throttle set screw with a plastic connecter shield from an electrical connector. just extended the set screw because we all know those set screws do not move after 20 years of being set
so i technically moved the idle up a couple hundred from where the IAC was running at when i disconnected it. 650 rpm in park then drops to around 575-600 when in a gear.
PERFECT!
for now, i jerry rigged the throttle set screw with a plastic connecter shield from an electrical connector. just extended the set screw because we all know those set screws do not move after 20 years of being set
so i technically moved the idle up a couple hundred from where the IAC was running at when i disconnected it. 650 rpm in park then drops to around 575-600 when in a gear.
PERFECT!
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
helirich, you devil's advocate.... hehehe...
Actually, there is no guessing involved here. The PCM already pointed out the issues and where they lie. Now if someone isn't willing to "listen" to what the truck/computer is trying to "tell" them and wants to chase ghosts, then they are quite welcome to do so but I don't see the point. Pulling the codes gives you the answers as to where the problem lies. But just pulling the codes and then clearing them and expecting that the problems will magically go away without repairing or replacing the components that are malfunctioning is a rather ridiculous notion.
That would be like going to the doctor to find out you have a broken arm, thanking him for telling you, and leaving without having him set the break so it can heal.
Hey Greystreak,
Do you remember this
"Then stay with the EFI! The guys understood you perfectly... the EFI IS the simple way! Besides that, if you go through all the obnoxious swapping to get BACK to a carburetor, you take the EEC-IV computer out of the mix which takes the ability to troubleshoot WITHOUT chasing ghosts and replacing things that MIGHT be bad completely out of your hands. You go back to guessing and hoping you guessed right.
Sounds like you guys are chasing ghosts and doing alot of guessing. LOL
Do you remember this
"Then stay with the EFI! The guys understood you perfectly... the EFI IS the simple way! Besides that, if you go through all the obnoxious swapping to get BACK to a carburetor, you take the EEC-IV computer out of the mix which takes the ability to troubleshoot WITHOUT chasing ghosts and replacing things that MIGHT be bad completely out of your hands. You go back to guessing and hoping you guessed right.
Sounds like you guys are chasing ghosts and doing alot of guessing. LOL
That would be like going to the doctor to find out you have a broken arm, thanking him for telling you, and leaving without having him set the break so it can heal.
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 328
Likes: 0
so pretty much its all down to the IAC. either it has a bad gasket, gummed up, plain out stopped working or the voltage to and from it is F'ed up.
i put a test light to the connectors and i saw a positive, and 2 neutral (not showing anything on my test light).
i was wondering, could i just use the voltage from the one pin, put a potentiometer in line and adjust the voltage to it or does it not work like that?
i put a test light to the connectors and i saw a positive, and 2 neutral (not showing anything on my test light).
i was wondering, could i just use the voltage from the one pin, put a potentiometer in line and adjust the voltage to it or does it not work like that?
Cargo Master
Joined: May 2004
Posts: 3,007
Likes: 5
My understanding of how the IAC works is that it's either open or closed. There's a solenoid that moves the valve open or lets it close. The solenoid is either powered and open or it's unpowered and closed. It may open and close at a rate that seems to make it adjusting but it's still either open or closed.
Idle speed is controlled by the PCM and connot be adjusted.
The IAC Valve Assembly is NOT ADJUTABLE and CANNOT BE CLEANED.
Idle speed is controlled by the PCM and connot be adjusted.
The IAC Valve Assembly is NOT ADJUTABLE and CANNOT BE CLEANED.
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 328
Likes: 0
My understanding of how the IAC works is that it's either open or closed. There's a solenoid that moves the valve open or lets it close. The solenoid is either powered and open or it's unpowered and closed. It may open and close at a rate that seems to make it adjusting but it's still either open or closed.
Idle speed is controlled by the PCM and connot be adjusted.
The IAC Valve Assembly is NOT ADJUTABLE and CANNOT BE CLEANED.
Idle speed is controlled by the PCM and connot be adjusted.
The IAC Valve Assembly is NOT ADJUTABLE and CANNOT BE CLEANED.
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Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
g k50, the iac can be cleaned and idle can be adjusted if the proper process is followed.
why do you say premium gas? premium does nothing for a stock motor other then empty your wallet due to the cost. it wont burn any cleaner either if thats what your thinking.
why do you say premium gas? premium does nothing for a stock motor other then empty your wallet due to the cost. it wont burn any cleaner either if thats what your thinking.
Junior User
Joined: Jan 2008
Posts: 70
Likes: 0
i took my spare trottle body to work and cleaned it with solvent for like 15 minutes. then brushed everything with a fine scraper brush. soaked it in solvent for 2 hours and then cleaned it all off with hot water.
anything else i need to do before i put it on my engine? do i need a new gasket for the throttle body/plenum?
after cleaning all the carbon and gunk off it, do you think it will help my engine at all?
anything else i need to do before i put it on my engine? do i need a new gasket for the throttle body/plenum?
after cleaning all the carbon and gunk off it, do you think it will help my engine at all?
Just a thought.
Good Luck
Kenny
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 328
Likes: 0
Did you take the TPS off of the throttle body before you did all this soaking and washing? If not there is a good chance that there is liquid in the TPS which will play hell with the resistance that it's has to have to give correct readings back to the PCM.
Just a thought.
Good Luck
Kenny
Just a thought.
Good Luck
Kenny
removed it prior to soaking it.
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