throttle body position problems

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Oct 26, 2023 | 11:48 AM

Mountain_anderson

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Mountain Pass

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throttle body position problems

Hi all,

Currently tracking down why my 1986 F150 has a rough idle. I checked the throttle position sensor and its normal voltage is 5.03, the signal without throttle is 0.94 but when given full throttle it rests at around 3.89 volts. Should full throttle not be 5.03 or am I wrong and its functioning correctly?

Oct 26, 2023 | 01:12 PM

Max Capacity

Lead Driver

Joined: Jun 2013

Posts: 5,668

Likes: 1,159

From: Tolland, CT

I'll assume you have 302EFI engine. This may help...

https://www.google.com/search?q=thro...t=gws-wiz-serp

Oct 26, 2023 | 01:39 PM

Max Capacity

Lead Driver

Joined: Jun 2013

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From: Tolland, CT

This link may be more help with voltages.

https://www.google.com/search?q=thro...t=gws-wiz-serp

Also see related threads below, the one from Chuckles,,, see post #4

Oct 26, 2023 | 01:43 PM

Max Capacity

Lead Driver

Joined: Jun 2013

Posts: 5,668

Likes: 1,159

From: Tolland, CT

In one of the related links below, I saw in post #4 it should be 5.0v at full throttle.

You may have broken parts inside yours.

Oct 26, 2023 | 01:58 PM

Mountain_anderson

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Mountain Pass

Joined: Feb 2021

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Yes 302 Efi

Oct 26, 2023 | 01:59 PM

Mountain_anderson

Thread Starter

Mountain Pass

Joined: Feb 2021

Posts: 180

Likes: 10

Inside the tps? Could it possibly be something wrong with the throttle body by chance and is there a way i could diagnose it? I just would like to know before I puchase a new one

Oct 26, 2023 | 02:05 PM

Max Capacity

Lead Driver

Joined: Jun 2013

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From: Tolland, CT

The first youtube video, the 20 minute one, shows the inside of his was broken, its just plastic in there.

Look through those links. I'm not the expert, I just did some searching. I doubt the TB is the issue, unless its filthy.

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Oct 26, 2023 | 02:37 PM

Franklin2

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From: Virginia

Quote:

Originally Posted by Mountain_anderson

Inside the tps? Could it possibly be something wrong with the throttle body by chance and is there a way i could diagnose it? I just would like to know before I puchase a new one

Take the throttle linkage cables off and then move it by hand while checking the voltage. Also make sure to look inside at the butterfies and make sure they are not all coked up with black greasy soot.

Oct 26, 2023 | 02:38 PM

#10

Franklin2

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From: Virginia

For your rough idle problem, I would first check the codes from the computer.

Oct 27, 2023 | 12:25 PM

#11

diggerrigger

Cargo Master

Joined: Sep 2006

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From: Evansville, Indiana

Quote:

Originally Posted by Franklin2

Take the throttle linkage cables off and then move it by hand while checking the voltage..

This^. With the throttle cable hooked up, are the throttle plates even opening all the way? In many cases with these EFI equipped trucks they are not.