Throttle Position Sensor swap ...
10-11-2008, 11:22 AM
#1
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Throttle Position Sensor swap ...
Is there an easy way to swap this out on a '93 5.0 AT? It feels like it's held in by screws, is that correct? Do I have to pull the throttle bodies to get at it? Please advise.
10-11-2008, 12:48 PM
#2
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You'll probably need to pull the throttle body. You'll need to get new gaskets, which will cost a total of about $5 for plenum gasket set at your local parts store.
That would make life a lot simpler, unless you have a magic screwdriver that will work around tight corners.
That would make life a lot simpler, unless you have a magic screwdriver that will work around tight corners.
10-11-2008, 08:10 PM
#3
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^+1 - have to pull the throttle body. IIRC, the screws are small Phillips-head.
A shop manual will help in describing how to re-align during installation - not too terribly difficult - but this is a job one only wants to do once.
A shop manual will help in describing how to re-align during installation - not too terribly difficult - but this is a job one only wants to do once.
10-12-2008, 10:07 AM
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Without a shop manual I'm not looking forward to it. 4 simple bolts, 2 phillips-head screws. What I would like to understand before tearing into it is, if it's held in place by 2 screws how do I know the screws are tight enough to hold the TPS in place so that it wont move under driving conditions but loose enough so that I can fine tune the TPS after all has been put back together? Someone please explain, thanks.
Last edited by Ekenfecker; 10-12-2008 at 10:17 AM.
10-12-2008, 11:21 AM
#5
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From the Chilton's manual - number 8136, for '87 - '91 trucks:
1) Disconnect the wiring harness from the TPS.
*****Caution - never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile!
2) Matchmark the sensor and throttle body for installation reference.
3) Remove the 2 retaining screws and remove the TPS.
4) Install the TPS so that the wiring harness is parallel with the venturi bores, then, rotate the TPS clockwise to align the scribe marks.
***** Caution - Slide the rotary tangs into position over the throttle shaft blade, then, rotate the TPS CLOCKWISE ONLY to the installed position. FAILURE TO INSTALL THE TPS IN THIS MANNER WILL RESULT IN EXCESSIVE IDLE SPEEDS!
5) Tighten the retaining screws to 16 in-lbs.
***** Note - When correctly installed, the TPS wiring harness should be pointing directly at the air bypass valve.
6) Connect the wiring.
While your vehicle is the next generation, I would assume the procedures would be similar, if not identical.
There is a voltage check you can do, but not sure what the target range is at the closed position. For some reason, 0.98VDC comes to mind????
1) Disconnect the wiring harness from the TPS.
*****Caution - never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile!
2) Matchmark the sensor and throttle body for installation reference.
3) Remove the 2 retaining screws and remove the TPS.
4) Install the TPS so that the wiring harness is parallel with the venturi bores, then, rotate the TPS clockwise to align the scribe marks.
***** Caution - Slide the rotary tangs into position over the throttle shaft blade, then, rotate the TPS CLOCKWISE ONLY to the installed position. FAILURE TO INSTALL THE TPS IN THIS MANNER WILL RESULT IN EXCESSIVE IDLE SPEEDS!
5) Tighten the retaining screws to 16 in-lbs.
***** Note - When correctly installed, the TPS wiring harness should be pointing directly at the air bypass valve.
6) Connect the wiring.
While your vehicle is the next generation, I would assume the procedures would be similar, if not identical.
There is a voltage check you can do, but not sure what the target range is at the closed position. For some reason, 0.98VDC comes to mind????
10-12-2008, 12:26 PM
#6
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There have been a few inconsistencies that have come up recently about this:
1) Chilton says to get the wiring pointing toward the IAC, Haynes says pointing away from the IAC. On my truck, it points away. The more I look at it and think about it, it shouldn't matter. It'll mount either way, and the rotation is the same no matter. With it pointing away, it's easier to probe the wires and check voltage.
2) Chilton's range of voltage is something like .66v to 1.22v when closed. It should run up to 5v wide open with a smooth climb along the way. Some reading on the 'net led me to believe that .98v was the sweet spot (more than one source agreed on that), but some forum members think that's incorrect.
You can test the voltage with a simple volt meter by probing the left and center wires. (looking down the pigtail toward the TPS) You need to do this with key on, engine off.
3) You need to set base idle with the IAC unplugged by adjusting the throttle stop screw. There is a sticker on it saying to never turn it, but that's where you have to start to get the idle right. From there, with everything plugged back in, you can turn the TPS to get the base voltage right.
4) Some TPS' have elongated mounting holes so you can adjust them, some don't. Some folks have elongated them with a drill, but you might end up murdering a brand new part in the process. If yours isn't the adjustable type, and you don't want to try the drill method, you won't have to worry about turning it anyway. Once it's mounted, it won't turn.
1) Chilton says to get the wiring pointing toward the IAC, Haynes says pointing away from the IAC. On my truck, it points away. The more I look at it and think about it, it shouldn't matter. It'll mount either way, and the rotation is the same no matter. With it pointing away, it's easier to probe the wires and check voltage.
2) Chilton's range of voltage is something like .66v to 1.22v when closed. It should run up to 5v wide open with a smooth climb along the way. Some reading on the 'net led me to believe that .98v was the sweet spot (more than one source agreed on that), but some forum members think that's incorrect.
You can test the voltage with a simple volt meter by probing the left and center wires. (looking down the pigtail toward the TPS) You need to do this with key on, engine off.
3) You need to set base idle with the IAC unplugged by adjusting the throttle stop screw. There is a sticker on it saying to never turn it, but that's where you have to start to get the idle right. From there, with everything plugged back in, you can turn the TPS to get the base voltage right.
4) Some TPS' have elongated mounting holes so you can adjust them, some don't. Some folks have elongated them with a drill, but you might end up murdering a brand new part in the process. If yours isn't the adjustable type, and you don't want to try the drill method, you won't have to worry about turning it anyway. Once it's mounted, it won't turn.
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10-12-2008, 01:56 PM
#8
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Is it possible or advisable to set it at .98v with the new TPS connected but prior to bolting the throttle body back on? Or do I put it all back together and then set it at .98v as a starting point?
Last edited by Ekenfecker; 10-12-2008 at 02:00 PM.
10-12-2008, 02:26 PM
#9
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Sounds worth a try. If you haven't taken the TB off yet, I'd go ahead and unplug the IAC so you can get your base idle set (if it needs to be adjusted). From there, if you want to try to get it set before putting everything back together, it should be in the right spot.