This week we installed a new Throttle Position Sensor (TPS) part #89452-14050 on our 92 with 338k. Occasional issues we were experiencing included: Random idle changes with AC off, engine stalling due to low rpms, hard starting, and erratic throttle response.
I did my best to test the sensor first on the vehicle to no success then on to my work bench. The test procedures are outlined in the FSM pages FI-64 through FI-66. Here's the free download of the FSM. http://tlc.cnlson.com/3FE REPAIR MANUAL.pdf
It does take several minutes to download.
The problem I noticed is that the readings on my digital meter never remained constant and never seemed to even stay similar. Next I ordered a TPS from Toyota parts of Dallas due to the shipping time to Oklahoma. Cost came in at $113.71 which included $15.68 of shipping. Just FYI, this part is a warehouse only item even from Dan so expect about 6 days or so to receive.
After receiving it I performed the adjustments outlined in the FSM. I performed the adjustments with 3 multimeters (2 digital and 1 analog). Here's the procedure:
1. Install .93mm feeler gauge between the throttle lever and stop screw. I positioned the TPS and throttle body in a vise with the 4 test points pointing at me horizontally. This makes it much easier to install your leads (off your multimeter) under the test points. Test points left to right are VC, VTA, IDL, E2 or up to down on your vehicle. Loosen the two screws, TPS will rotate counter clockwise via spring, position your two leads on the IDL and E2 tabs, set your meter to Ohms and start slowly turning the TPS clockwise until your digital meter reads a "1" (infinity or no continuity).
If you are using an analog meter, the Ohm meter will move to the left or infinity. While carefully holding the sensor securely, tighten the two screws equally at this point. Several posts I have read stated the Ohm meter or the volts should go to 0. That's one of the problems I was having because that is all wrong.
2. Install a .77mm feeler gauge and check for continuity. If using an analog meter, your needle will move to the right which is 0 which means there is continuity. On a digital meter it will read a constant number anything but a 1.
3. Install a 1.09mm feeler gauge and check for continuity. There should be no continuity as displayed above in step 1.
4. Now for the last test that proved the TPS was the cause of the idle issues we were experiencing. This is where the analog meter really shined. Put your test leads on VTA and E2 and slowly increase throttle to full throttle. On the old TPS, readings started at 1 and were ERRATIC all the way to 5. Now for the new TPS, the needle readings were smooth as silk starting at 0 and ending at a 3. This now explained everything.
We've only driven it for a day or two but things we are noticing are: Much more responsive and smoother throttle, higher full throttle rpm shift points (was 3,850 going from 1st to 2nd, now 4,200), Idle now stays at 650 or higher and no random idle fluctuations. I'm curious to check the results but I believe our fuel mileage should go upwards due to this replacement and proper adjustment.
Now for what I learned. I really liked using the analog meter because of the ability to watch the needle move. The digital meters work fine they just don't read as smoothly as an analog "needle" meter. The .93mm gauge just sets your sensor to the first point of no continuity. All thicker gauges above .93, should show no continuity as well. Anything less than .93, for instance the .77 will show continuity. Never loosen the adjustment screws and try to make the adjustment while on the vehicle. This makes it virtually impossible to install the feeler gauges at a 90 degree angle to the throttle stop screw. When removing the throttle assembly you really do not need to drain your coolant to remove the two hoses on the bottom (as long as you perform this on a cold engine). There are other tests listed in the FSM, I performed them as well but only listed in detail what I believed to be the most important ones for our vehicle.
I can't think of anything else. Time for us to enjoy the ride. Will report back with fuel mileage readings as they become available. Hope this helps some others out there with the mighty 3FE.
Steve
I did my best to test the sensor first on the vehicle to no success then on to my work bench. The test procedures are outlined in the FSM pages FI-64 through FI-66. Here's the free download of the FSM. http://tlc.cnlson.com/3FE REPAIR MANUAL.pdf
It does take several minutes to download.
The problem I noticed is that the readings on my digital meter never remained constant and never seemed to even stay similar. Next I ordered a TPS from Toyota parts of Dallas due to the shipping time to Oklahoma. Cost came in at $113.71 which included $15.68 of shipping. Just FYI, this part is a warehouse only item even from Dan so expect about 6 days or so to receive.
After receiving it I performed the adjustments outlined in the FSM. I performed the adjustments with 3 multimeters (2 digital and 1 analog). Here's the procedure:
1. Install .93mm feeler gauge between the throttle lever and stop screw. I positioned the TPS and throttle body in a vise with the 4 test points pointing at me horizontally. This makes it much easier to install your leads (off your multimeter) under the test points. Test points left to right are VC, VTA, IDL, E2 or up to down on your vehicle. Loosen the two screws, TPS will rotate counter clockwise via spring, position your two leads on the IDL and E2 tabs, set your meter to Ohms and start slowly turning the TPS clockwise until your digital meter reads a "1" (infinity or no continuity).
If you are using an analog meter, the Ohm meter will move to the left or infinity. While carefully holding the sensor securely, tighten the two screws equally at this point. Several posts I have read stated the Ohm meter or the volts should go to 0. That's one of the problems I was having because that is all wrong.
2. Install a .77mm feeler gauge and check for continuity. If using an analog meter, your needle will move to the right which is 0 which means there is continuity. On a digital meter it will read a constant number anything but a 1.
3. Install a 1.09mm feeler gauge and check for continuity. There should be no continuity as displayed above in step 1.
4. Now for the last test that proved the TPS was the cause of the idle issues we were experiencing. This is where the analog meter really shined. Put your test leads on VTA and E2 and slowly increase throttle to full throttle. On the old TPS, readings started at 1 and were ERRATIC all the way to 5. Now for the new TPS, the needle readings were smooth as silk starting at 0 and ending at a 3. This now explained everything.
We've only driven it for a day or two but things we are noticing are: Much more responsive and smoother throttle, higher full throttle rpm shift points (was 3,850 going from 1st to 2nd, now 4,200), Idle now stays at 650 or higher and no random idle fluctuations. I'm curious to check the results but I believe our fuel mileage should go upwards due to this replacement and proper adjustment.
Now for what I learned. I really liked using the analog meter because of the ability to watch the needle move. The digital meters work fine they just don't read as smoothly as an analog "needle" meter. The .93mm gauge just sets your sensor to the first point of no continuity. All thicker gauges above .93, should show no continuity as well. Anything less than .93, for instance the .77 will show continuity. Never loosen the adjustment screws and try to make the adjustment while on the vehicle. This makes it virtually impossible to install the feeler gauges at a 90 degree angle to the throttle stop screw. When removing the throttle assembly you really do not need to drain your coolant to remove the two hoses on the bottom (as long as you perform this on a cold engine). There are other tests listed in the FSM, I performed them as well but only listed in detail what I believed to be the most important ones for our vehicle.
I can't think of anything else. Time for us to enjoy the ride. Will report back with fuel mileage readings as they become available. Hope this helps some others out there with the mighty 3FE.
Steve
