TPI throttle positioning sensor question
Thread Starter
Le Mans Master
Joined: Aug 2004
Posts: 5,019
Likes: 2
From: Russellville, Kentucky 1967 Sting Ray & 2001 C5
I dunno. Some of what everyone has said in this thread doesn't seem to apply to my car. I put my OTC Genesis scanner on the car:
sensor clockwise = voltage down
sensor counterclockwise = voltage up
There is no power to the sensor with "key on - motor off."
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
I checked for vacuum leaks - none. What now?
sensor clockwise = voltage down
sensor counterclockwise = voltage up
There is no power to the sensor with "key on - motor off."
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
I checked for vacuum leaks - none. What now?
Team Owner
Joined: Jul 2004
Posts: 28,430
Likes: 3,279
From: Hartford WI
There is no power to the sensor with "key on - motor off."
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
Way too low a voltage. Sounds like the ECM is adjusting based on other inputs like MAP or MAF depending on which one you have instead of TPS
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
I dunno. Some of what everyone has said in this thread doesn't seem to apply to my car. I put my OTC Genesis scanner on the car:
sensor clockwise = voltage down
sensor counterclockwise = voltage up
There is no power to the sensor with "key on - motor off."
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
I checked for vacuum leaks - none. What now?
sensor clockwise = voltage down
sensor counterclockwise = voltage up
There is no power to the sensor with "key on - motor off."
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
I checked for vacuum leaks - none. What now?
Team Owner
Joined: Jan 2003
Posts: 20,305
Likes: 240
From: Summerland B.C. Canada
I dunno. Some of what everyone has said in this thread doesn't seem to apply to my car. I put my OTC Genesis scanner on the car:
sensor clockwise = voltage down
sensor counterclockwise = voltage up
There is no power to the sensor with "key on - motor off."
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
I checked for vacuum leaks - none. What now?
sensor clockwise = voltage down
sensor counterclockwise = voltage up
There is no power to the sensor with "key on - motor off."
Idle is directly affected but the TPS adjustment on my car. With engine running I adjusted voltage per the scanner to .18 vdc idle RPM 1000. That is with the sensor fully clockwise. Counterclockwise rotation increases voltage and RPM.
I checked for vacuum leaks - none. What now?
Where does your scanner hook up ? Do you have an ALDL port ? Can you close the IAC, by jumping 2 terminals ?
What is the target idle rpm in the bin ? Does your scanner show this ?
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
Another way to go about it to set idle using IAC counts. With scanner plugged in, motor at operating temp, tps plugged in (as is), and at idle, what is the current IAC counts ?
If the motor is relatively modded (cam etc.) I would be looking for around 40 cts. (w/ idle inteded to be around 850 ish rpm), stock 10-30 cts. (650-750 rpm). Changing the min. air screw will change cts. and idle rpm. It would be nice to know the target idle rpm in the bin as well as the scan reading.
If the motor is relatively modded (cam etc.) I would be looking for around 40 cts. (w/ idle inteded to be around 850 ish rpm), stock 10-30 cts. (650-750 rpm). Changing the min. air screw will change cts. and idle rpm. It would be nice to know the target idle rpm in the bin as well as the scan reading.
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
Maybe, but it appears as though his system doesn't not need the reference v. signal to start the car. My thinking is that perhaps the TPS is not currently wired to a true switched power source. In any event at idle, at operating temp., 1.8v. would be a high signal, and could indicate the TB blade is opened to far.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Maybe, but it appears as though his system doesn't not need the reference v. signal to start the car. My thinking is that perhaps the TPS is not currently wired to a true switched power source. In any event at idle, at operating temp., 1.8v. would be a high signal, and could indicate the TB blade is opened to far.
Jake
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Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
sorry bout that..yes typo on my part, and yes .18 is too low.
I still think it would be beneficial to know the IAC cts., check or re-do wiring from the ecm for a reference signal and go from there.
I still think it would be beneficial to know the IAC cts., check or re-do wiring from the ecm for a reference signal and go from there.
