High RPM shift 2nd to 3rd...ALWAYS

[Adam F]

Now, I've been driving a 3rd gen 4Runner now for 10 years. I know how the 2nd to 3rd shift is supposed to work. Temps below 40 degrees or so, the ECU makes the 2nd to 3rd shift point right around 2750 until a certain temperature is reached, to help warm the engine up faster.

Problem is, my truck now does this 100% of the time, no matter the temperature. Its close to 90 degrees and its doing it.

So what exactly tells the computer when to make this shift point? ECT sensor? Temp sensor in the trans?

I have a bluetooth scanner on my android phone, and I can monitor the coolant temperature, and its reading perfectly normal, starts out and ambient temperature, and goes up to full temp, smoothly.

Now, isn't there 2 temp sensors, one that gives the dash gauge readings, (is this the one I'm reading using ODBII?) and then one that tells the ECU the temperature?


I'm assuming that the ECU sensor is up front under the fuel rail? If so, anyone got a part number for this? Parts store can only find one temp sender, not sure which one it is.

Thanks. 3.4L. Getting lousy fuel mileage, about 13 around town, 15 hwy. I used to get 17-18 city and 20-21 highway not that long ago. I replaced the upstream o2 sensor a while back with little change.

 

[tre9er]

Mine does this when I first drive it each day, but only the first few minutes, then it shifts normally. It does it regardless of the temp outside. I believe it's a factor of the trans temp more than ambient temp.

 

[chimpy]

Trans temp

 

[Tommy4Runner]

My 2000 has done it since day one as well and thought there might be a problem but have since driven 3 other 3rd gen. and they all do the same thing and its only the first couple min. driving it then shifts great afterwards so to me trans temp has to reach a certain temp.