How to replace the throttle position sensor?

MATTD88

MEMBER
1990 BUICK CENTURY
118,000 MILES

I would like to ask someone on here how to replace the throttle position sensor on my car listed above. It's a 1990 v6 3.3l engine. I have been having a problem with my car stalling and shutting off while driving and or idling while its in drive. I had someone look at it and they told me its not fuel related so he said to look into sensors replacement. I was going to first try replacing the mass air flow sensor and then the throttle sensor to see if that fixes it. Any help is greatly appreciated thanks.

4 Replies

CARADIODOC

MECHANIC
33,916 POSTS

Throwing random parts at a problem is the most expensive and least effective way to diagnose a problem. Additionally, you will be inserting a bunch of new variables to confuse the Engine Computer even more. The exception is if you already have those parts on hand.

The throttle position sensor will not cause stalling. It can cause a hesitation on acceleration but that will be detected by the computer and it will set a related diagnostic fault code to tell you. The mass air flow sensor can cause stalling but that is not nearly as common as it was years ago. Has anyone even checked yet for any fault codes? If there are none set, the fuel supply system is still a good suspect.

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Sunday, June 2nd, 2013 AT 8:41 PM

MATTD88

MEMBER
23 POSTS

Yeah I agree with you about spending money on parts, but I was going to get the parts from a scrap yard since the mass air flow sensor is so costly to buy new. I had someone run fuel tests on the car and they told me it's not the fuel supply or anything like that. It stalls and shuts off when I'm pressing the gas pedal so I figure its something to do with the acceleration. The computer was replaced recently because I was getting a code that was a quad driver circuit that was in the computer and I was having like the same problem but I unplugged the wire going into the tcc solenoid going into my transmission and that fixed it. What I don't understand is when the computer was replaced the check engine light went out and the wire plugged in, it ran good for several weeks but then just started acting up going up a mountain a few weeks ago, I haven't been able to drive it since.

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Monday, June 3rd, 2013 AT 4:17 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon,

There is an idle air control motor on the throttle body that controls the idle speed and quality.

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

https://www.2carpros.com/articles/stall-at-idle

I would replace that and clean the throttle body of all carbon deposits.

https://www.2carpros.com/articles/throttle-actuator-service

Roy

REMOVAL:

1. Disconnect the idle air control (IAC) valve electrical connector.
2. Remove the IAC valve attaching screws.
3. Remove the IAC valve assembly.

CAUTION: On IAC valves that have been in service, DO NOT push or pull on the old IAC valve pintle. The force required to move the pintle may damage the threads on the worm drive.

4. Clean the IAC valve O-ring sealing surface, pintle valve, seat and air passage.
Use carburetor cleaner and a parts cleaning brush to remove carbon deposits. DO NOT use a cleaner that contains Methyl Ethyl Ketone. It is an extremely strong solvent, and not necessary for this type of deposit.
Shiny spots on the pintle or seat are normal, and do not indicate misalignment or a bent pintle shaft.
If the air passage has heavy deposits, remove the throttle body for complete cleaning.
Inspect the IAC valve O-ring for cuts, cracks or distortion. Replace if damaged.

NOTE: If installing a new IAC valve, be sure to replace with an identical part. IAC valve pintle shape and diameter are designed for specific application.

Idle Air Control Valve
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INSTALLATION:

1. If installing a new IAC valve, measure the distance between the tip of the pintle and the mounting flange.
If greater than 28 mm, use finger pressure to slowly retract the pintle. The force required to retract the pintle of a new valve will not cause damage to the valve.
2. Lubricate the IAC valve O-ring with clean engine oil.
3. Install the IAC valve assembly.
4. Install the IAC valve attaching screws, and tighten to 3.0 Nm (27 lb.in).
5. Connect the IAC valve electrical connector.
6. START the engine and allow it to reach operating temperature.

NOTE: No physical adjustment of the IAC valve assembly is required after installation. The IAC valve is reset by the ECM when the ignition is turned ON, and then OFF.

Reset

To reset the Idle Air Control (IAC) valve pintle position, proceed with the following:

ENGINE RUNNING:

Accelerate vehicle to over 30 mph OR run engine to over 2000 rpm. Ground the diagnostic test terminal (ALDL) for ten seconds, then remove the ground. Turn the ignition "OFF," then restart the engine and check for the proper idle operation.

ENGINE NOT RUNNING:

Turn the ignition switch "ON" with the engine "OFF." Ground the ALDL diagnostic test terminal for 5 seconds to seat the IAC valve pintle. Remove the ground to retract the IAC valve pintle . Turn ignition "OFF" for 10 seconds. Start engine and check for proper idle.

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