3.0 3VZE Throttle Position Sensor + Transmission
12-08-2016, 12:49 PM
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3.0 3VZE Throttle Position Sensor + Transmission
Just Replaced my TPS again, the inside plastic pieces were broken, this one lasted about 2.5 years and yes it was a cheapo. New one is Denso. I am posting because although there are plenty of posts that reference the TPS for the 3VZE, I was having difficulty locating a thread where my exact issues or close were discussed so hopefully this can help someone in the future. My 4runner is a 94' 3.0 Auto Trans 257K. My symptoms were . . .
1) Transmission would default to highest gear. Meaning, I had to manually upshift *most* of the time or it would shift into the highest gear almost immediately. So I would start from stop and get it to about 10mph and it would shift into overdrive. Once it was in that gear, it wouldn't downshift so that had to be done manually as well which was really awesome when I started to go up any hills.
2) Terrible fuel economy! Like, 7mpg bad.
3) Engine Trouble Codes - 25) FUEL TOO LEAN 26) FUEL TO RICH 41) TPS 71) EGR
4) Started after 3-4 seconds of cranking instead of right away like normal for my truck.
CONCLUSION - Testing then replacing the TPS fixed ALL of my problems. If a 3.0 has many weird symptoms involving fuel and transmission, check the TPS first! My trouble code did not come on for the TPS until the symptoms worsened. I also had several problems a few years ago that I posted about here https://www.yotatech.com/forums/f116...-start-281694/ and several helpful members such as RJR said things like "I would carefully check out the VAFM and the TPS. Both of those inform the ECU about input conditions for the engine (air flow and throttle position). It uses that information to set fuel flow and transmission shift points, among other things." This helped me eventually trace the problem to a loose ground that went to the TPS! And this link is awesome for DIAGNOSING THE TPS http://www.4crawler.com/4x4/CheapTri...shtml#MoreInfo AND I highly recommend the upgrade idea of replacing the TPS screws from phillips heads to allen keys, you'll thank yourself later. I did. Thanks again to all of the members who offer their time and expertise on this site. Sorry so long, I tried to post this in the Maintenance/Repair forum but I was restricted for posting there for some reason. If anyone has anything to add about the TPS and other problems it can cause, please post!
1) Transmission would default to highest gear. Meaning, I had to manually upshift *most* of the time or it would shift into the highest gear almost immediately. So I would start from stop and get it to about 10mph and it would shift into overdrive. Once it was in that gear, it wouldn't downshift so that had to be done manually as well which was really awesome when I started to go up any hills.
2) Terrible fuel economy! Like, 7mpg bad.
3) Engine Trouble Codes - 25) FUEL TOO LEAN 26) FUEL TO RICH 41) TPS 71) EGR
4) Started after 3-4 seconds of cranking instead of right away like normal for my truck.
CONCLUSION - Testing then replacing the TPS fixed ALL of my problems. If a 3.0 has many weird symptoms involving fuel and transmission, check the TPS first! My trouble code did not come on for the TPS until the symptoms worsened. I also had several problems a few years ago that I posted about here https://www.yotatech.com/forums/f116...-start-281694/ and several helpful members such as RJR said things like "I would carefully check out the VAFM and the TPS. Both of those inform the ECU about input conditions for the engine (air flow and throttle position). It uses that information to set fuel flow and transmission shift points, among other things." This helped me eventually trace the problem to a loose ground that went to the TPS! And this link is awesome for DIAGNOSING THE TPS http://www.4crawler.com/4x4/CheapTri...shtml#MoreInfo AND I highly recommend the upgrade idea of replacing the TPS screws from phillips heads to allen keys, you'll thank yourself later. I did. Thanks again to all of the members who offer their time and expertise on this site. Sorry so long, I tried to post this in the Maintenance/Repair forum but I was restricted for posting there for some reason. If anyone has anything to add about the TPS and other problems it can cause, please post!
12-12-2016, 08:16 PM
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This is good to know. I have trouble code 25 (too lean) and 71 (EGR). Terrible gas mileage too. But the main problem is cold starts when outside temp is below 60 degrees. Cranks and cranks. Won't start unless I warm up the coolant and CSI sensors with a hair dryer. Seems to be related to outside temp. Above 60 degrees and it starts no problem. Once the engine starts and warms up it restarts no problem as long the engine is warm. Another 3.0 owner was having problem with cold starts, replaced the TPS and the problem was solved. So I am going to test the TPS and go from there.
