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Unread 02-12-2008, 02:10 PM   #1
pgurt1
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Throttle Position Sensor

THe gas gas mileage on my 2004 Rubicon (auto/trns) has been off by about 20% over the past couple of months. Driving habits and terrain unchanged. Nothing new added. My check engine light code reads out P-0122 and the chart says Throttle Position Sensor Voltage Low

Is this part easily replaced? Where exactly is this part located.
Thanks,
Peter

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Unread 02-12-2008, 02:17 PM   #2
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Quote:
Originally Posted by pgurt1 View Post
THe gas gas mileage on my 2004 Rubicon (auto/trns) has been off by about 20% over the past couple of months. Driving habits and terrain unchanged. Nothing new added. My check engine light code reads out P-0122 and the chart says Throttle Position Sensor Voltage Low

Is this part easily replaced? Where exactly is this part located.
Thanks,
Peter
The throttle position sensor is located on the throttle body, and has the three wires attached. It is held in with two torx screws. You can adjust these using a volt meter. Throttle Position Sensors work with the Jeep's computer and the MAP Sensor to control the engine's air/fuel mixture. Having a under-performing can affect your Jeep's power performance and fuel mileage.

I will try to look for instructions for this.


They costs about $85.00 at your local auto parts store.
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Last edited by CRAWLING 98; 02-12-2008 at 02:29 PM..
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Unread 02-12-2008, 02:24 PM   #3
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TPS Adjustment Procedure - 4.0 Liter Engine With Manual Transmission

1. Turn the ignition switch to the "ON" position.
2. Do not remove the electrical connector from the TPS. Connect the positive lead of the voltmeter to terminal A and the negative lead to terminal B of the TPS connector (Figure 1). The leads must be inserted through the back of the connector to make contact with the terminals. The terminal identification letters are molded into the connector.
3. with the throttle plate in the closed position, note the "input" voltage. It should be approximately 5.0 volts.
4. Remove the voltmeter positive lead from terminal A and connect it to terminal C. The "output" voltage should be 0.8 volt (16% of input voltage). If this is not the case, continue with this procedure.
5. Adjust output voltage as follows: with the voltmeter leads still attached, carefully loosen the sensor mounting screws and slowly rotate the sensor until the output reading is 0.8 volt with the throttle closed. Then, tighten the sensor mounting screws securely. Be sure not to disturb the sensor's position while tightening the screws. Adjustment is now complete.
tps0.gif  
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Unread 02-12-2008, 02:48 PM   #4
pgurt1
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4x4 Gray,
Thanks for the info. Two questions:
Is the process the same for an automatic trans?
Should I try this adjustment before I invest in a new sensor
THanks,
Peter
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Unread 02-12-2008, 02:57 PM   #5
Jerry Bransford
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Originally Posted by 4x4grey88 View Post
TPS Adjustment Procedure - 4.0 Liter Engine With Manual Transmission

1. Turn the ignition switch to the "ON" position.
2. Do not remove the electrical connector from the TPS. Connect the positive lead of the voltmeter to terminal A and the negative lead to terminal B of the TPS connector (Figure 1). The leads must be inserted through the back of the connector to make contact with the terminals. The terminal identification letters are molded into the connector.
3. with the throttle plate in the closed position, note the "input" voltage. It should be approximately 5.0 volts.
4. Remove the voltmeter positive lead from terminal A and connect it to terminal C. The "output" voltage should be 0.8 volt (16% of input voltage). If this is not the case, continue with this procedure.
5. Adjust output voltage as follows: with the voltmeter leads still attached, carefully loosen the sensor mounting screws and slowly rotate the sensor until the output reading is 0.8 volt with the throttle closed. Then, tighten the sensor mounting screws securely. Be sure not to disturb the sensor's position while tightening the screws. Adjustment is now complete.
Where did you find that adjustment procedure and if it came from a '97 or newer Jeep TJ factory service manual, what model year is it from? Thanks!
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Unread 02-12-2008, 03:05 PM   #6
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Originally Posted by Jerry Bransford View Post
Where did you find that adjustment procedure and if it came from a '97 or newer Jeep TJ factory service manual, what model year is it from? Thanks!
I doubt you'll get an answer. He was probably just assassinated by the company that makes those things.
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Unread 02-12-2008, 04:20 PM   #7
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Searching "TPS Adjustment Procedure - 4.0 Liter Engine With Manual Transmission" comes up with the exact text for adjusting an 87 cherokee on a qa site..

04 tj sm lists the voltage ranges with no adjustment procedure.
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Unread 02-12-2008, 04:45 PM   #8
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I posted a bit about my TPS just this afternoon, this is perfect! I had no idea you could adjust it, thanks so much!
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Unread 02-12-2008, 05:46 PM   #9
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Originally Posted by d26k View Post
04 tj sm lists the voltage ranges with no adjustment procedure.
Precisely why I asked, neither does my '97 FSM. My '97 TJ's TPS is not adjustable and there is no calibration procedure for it.
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Unread 02-12-2008, 11:38 PM   #10
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Ahh, but there is a way to adjust them. This was alittle 'trick' to gain some better throttle response on the 4.7. Remove the TPS, clamp it gently in a vise and using a drill bit slightly larger than the hole in the bushing, begin to drill it out. What will happen is the bushing will spin and will melt loose from the plastic of the TPS. remove this bushing. Now re-install the TPS and use some very small and thin washers under the bolts to tighten down the TPS. Check the closed throttle voltage and rotate the TPS to get the .8 volts. With the 4.7 .75 to .93 volts worked best.
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Unread 02-13-2008, 06:02 AM   #11
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Originally Posted by madduc View Post
Ahh, but there is a way to adjust them. This was alittle 'trick' to gain some better throttle response on the 4.7. Remove the TPS, clamp it gently in a vise and using a drill bit slightly larger than the hole in the bushing, begin to drill it out. What will happen is the bushing will spin and will melt loose from the plastic of the TPS. remove this bushing. Now re-install the TPS and use some very small and thin washers under the bolts to tighten down the TPS. Check the closed throttle voltage and rotate the TPS to get the .8 volts. With the 4.7 .75 to .93 volts worked best.
If you have to do all of that work, you have the wrong TP sensor. As long as the computer can determine the correct closed throttle (CT), part throttle (PT) and wide-open throttle (WOT) conditions, you should be fine. There are certain cut-off voltage values that determine these conditions. If they are out of range you will get driveability problems but the % of error is very forgiving and that sensor would have to be way-off target to be out of range. The actual throttle angle measured by the TPS does not determine the precise fuel amount. The primary use of the TPS is to determine CT, PT, WOT and driver intentions. Driver intentions includes the rate of opening and closing and if the throttle is opening or closing. The precise fuel amounts are fine tuned utilizing from what has been learned through closed-loop operations. The most impotant sensor here would be the upstream O2 sensor(s). Next in line would be the MAP sensor, TPS, Intake Air Temperature sensor, Engine Coolant Temperature sensor, etc. During the 'learning' process, the unique relationship between all these sensors is mapped to return optimum performance. Also, it is good practice that whenever a major sensor is replaced, to reset the PCM.
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Unread 02-14-2008, 12:35 AM   #12
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Quote:
Originally Posted by Jerry Bransford View Post
Where did you find that adjustment procedure and if it came from a '97 or newer Jeep TJ factory service manual, what model year is it from? Thanks!
Quote:
Originally Posted by d26k View Post
Searching "TPS Adjustment Procedure - 4.0 Liter Engine With Manual Transmission" comes up with the exact text for adjusting an 87 Cherokee on a qa site..

04 tj sm lists the voltage ranges with no adjustment procedure.
Yes Jerry I found it online searching for Jeep TPS adjustment (or something like that )
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Unread 02-14-2008, 12:41 AM   #13
Jerry Bransford
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Originally Posted by 4x4grey88 View Post
Yes Jerry I found it online searching for Jeep TPS adjustment (or something like that )
Certanly but is that procedure valid for his TJ??? It's not for my '97 since its TPS is not adjustable and there is no calibration procedure listed in the FSM. I just don't want the guy thinking there's a calibration procedure for his TJ when the procedure you quoted may not be for a TJ.

Again, what model and year Jeep is that procedure you found for?
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Unread 02-14-2008, 12:47 AM   #14
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Quote:
Originally Posted by Jerry Bransford View Post
Certanly but is that procedure valid for his TJ??? It's not for my '97 since its TPS is not adjustable and there is no calibration procedure listed in the FSM. I just don't want the guy thinking there's a calibration procedure for his TJ when the procedure you quoted may not be for a TJ.

Again, what model and year Jeep is that procedure you found for?
I understand but its worth a look to see, and if not he will have to replace it.
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Unread 02-14-2008, 12:48 AM   #15
Slithering_Joe
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People think there is a "sweet spot" in the adjustment of the TP sensor. The TPS just doesn't operate that way.
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