97 F150 problems
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Junior User
Joined: Jul 2013
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97 F150 problems
I bought a '97 Ford F150 v6 5spd 4x4 a couple weeks ago and i'm starting to have a couple problems. My first is simply it is acting real hard to start when cold it barely cranks at first and it finally starts. And yesterday i was driving into town and i put it in neutral and coasted to a stop light. While i was waiting at the light it started to die but i gave it gas and it corrected itself. Then last night i was going to my driveway and i coasted to my driveway in neutral and it died on me. I figured it was just starving for something since it was only at an idle but i really don't know these trucks that well. Thanks.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
With no other info to run with, I would recommend you remove the Intake Air Controller for a cleaning and be sure the internal pintel slides freely.
Use spray can cleaner meant for throttle body use.
Also remove the big intake hose from the throttle body and spray clean inside it's diameter and plate while holding the throttle open.
Use up the whole can until the cleaner run out clean.
Good luck.
Use spray can cleaner meant for throttle body use.
Also remove the big intake hose from the throttle body and spray clean inside it's diameter and plate while holding the throttle open.
Use up the whole can until the cleaner run out clean.
Good luck.
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Junior User
Joined: Jul 2013
Posts: 75
Likes: 1
So you're saying that it wanting do die at an idle is an intake issue? I know the filter is clean and there's no check engine light but that it's sort of random i don't understand because it has only done this twice. And is the way it starts rough when cold normal or could it be the battery?
Postmaster
Joined: Jun 2014
Posts: 3,206
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From: Oakhust NJ Jersey Shore
The IAC idle air control valve is what controls the engine speed on that truck. its nothing than a forced vacuum leak. the wide the valve opens the faster the idle. they are common for getting sooted up and the pintle that controls the valve gets gummy too, start with maintainance, clean the IAC, clean the throttle body and mass air flow sensor, make sure your EGR valve isnt sticking open, same thing soot and carbon build up. if it runs fine the rest of the time, that is what i would look at first, also check for vacuum leaks, that can throw the idle off aswell
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Cold start:
Key to run powers the computer, it checks the value of the cylinder head temp sensor and the intake air temp sensor.
This sets the IAC open, richens fuel injection and advances the timing.
The result is higher idle speed until the OX sensors come up to temperature and coolant begins the heat.
You can see from this the IAC is a key part of the operation as is the throttle plate that is held open a small amount by the throttle stop screw. If the plate open area is gummed shut the expected air is not there as a base idle air flow.
The throttle plate air flow is the base idle if the IAC were closed.
To see this, remove the IAC connector while engine is at normal idle.
The result is the engine runs on the throttle plate airflow at a lower idle speed but is uncontrolled.
This IAC is the sole controller of normal dynamic idle.
The idle RPM is a fixed value in the computer program that holds hot idle to within +/- 50 rpm.
How it does it is by using the crank sensor as a tach signal to feed back the crank RPM to compare with the idle table.
If it does not match, the IAC is commanded to open or close as needed continuously until it does match and keep it within the limits.
Good luck..
Key to run powers the computer, it checks the value of the cylinder head temp sensor and the intake air temp sensor.
This sets the IAC open, richens fuel injection and advances the timing.
The result is higher idle speed until the OX sensors come up to temperature and coolant begins the heat.
You can see from this the IAC is a key part of the operation as is the throttle plate that is held open a small amount by the throttle stop screw. If the plate open area is gummed shut the expected air is not there as a base idle air flow.
The throttle plate air flow is the base idle if the IAC were closed.
To see this, remove the IAC connector while engine is at normal idle.
The result is the engine runs on the throttle plate airflow at a lower idle speed but is uncontrolled.
This IAC is the sole controller of normal dynamic idle.
The idle RPM is a fixed value in the computer program that holds hot idle to within +/- 50 rpm.
How it does it is by using the crank sensor as a tach signal to feed back the crank RPM to compare with the idle table.
If it does not match, the IAC is commanded to open or close as needed continuously until it does match and keep it within the limits.
Good luck..
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