I have a 1997 Toyota camry, 4 cylinder, 4 speed automatic transmission (original transmission and engine), with 216,000 miles. when i start the car up in the morning the engine revs to almost 1800 rpm and stays there, i don't want to put it in gear for fear of destroying my already old transmission. I watched scotty's video on making my car run better with some spray cleaner, but it did not work. what should i do next? one person recommended i change my coolant temperature sensor?
There are a few issues I can think of that can cause this.
1) The Coolant Temp Sensor: I would start here. If the Coolant Temp Sensor is constantly sending the signal that the engine is "cold" then the cold start "idle up" circuit may remain (although this "should" be flagged as a sensor issue). There are a couple of these so you will want to check a service manual to locate them.
Also, these sensors use an "Ohms" resistance range that "should" change depending upon the temp of the coolant. Using a Toyota factory service manual aka FSM (available online in PDF or Digital download) you can in test these sensors yourself using the procedures in the FSM. Follow FSM for steps to perform necessary testing steps.
Cost for aftermarket temp sensor is anywhere from about $25 - $60 ea
2) Thermostat is stuck in the open position, therefore the engine runs cold for a (much) longer period of time until the car eventually warms up but might take 15 - 20+ minutes of driving to near the normal temp mark. Even then, if the thermostat is stuck open, the care may never quite reach proper temp (although if the vehicle is warming (and temp shows it's warming) then I certainly would expect RPM to drop within 10min (even with stuck thermostat)
Follow FSM for steps to perform necessary testing steps.
3) Idle Air Control valve (IAC). This valve is on the throttle body (throttle plate of the old carbs) and controls the amount of intake air that is allowed to enter into the intake system. It opens and closes based upon multiple factors such as engine coolant temp, air temp, etc. and as they age the get very gooey internally and don't like to open and close as they should (stuck or very slow to move).
Follow FSM for steps to perform necessary testing steps but cleaning these can be very tricky as they are sometimes sealed and it may be difficult to effectively clean the assembly. I would try cleaning with carb-cleaner and then follow up with rinsing / cleaning with CRC Plactic Safe Electronic Cleaner.
If you need to replace, I would not use an after-market but spend the ~$150.00-ish for an OEM Toyota IAC
4) Worn Throttle Position Sensor (TPS). As these age, they develop micro-cracks in the resistance material which appears as a "static-like" signal to the Engine computer (ECU) which can be interpreted as an incorrect signal. If the resistance is incorrect the ECU may believe the engine throttle is at a higher throttle position than "idle". (usually this type of issue results in poor idle or a stumbling acceleration but still possible). I would check this last and of course, Follow FSM for steps to perform necessary testing steps.
If you need to replace, I would not use an after-market but spend the ~$150.00-$200.00 for an OEM Toyota TPS but only after testing using FSM.
Also, I use only Factory Service Manuals (FSM). You can purchase used original FSM on Ebay and other online places or a Digital version. Prices range. Usually the digital FSM on DVD is a lot cheaper but if you like and want to keep the car, invest in the original Toyota FSM which run anywhere from average of about $50 - $150:
PS - Don't buy Chilton's or Haynes manuals. Buy the Toyota FSM.
It doesn’t drop at all after a few minutes?
@Asianbro0704 The older fuel injected motors will rev up higher sometimes on a cold start before dropping down. It’s more prevalent in cold temps because the fuel thickens a little bit so the vehicle is trying to move fuel more quickly to compensate. After a few min it should drop down to normal. But if it’s not dropping down at all there’s a few issues it could be.
no mine will go about 5 minutes before even a slight drop. My wifes car will idle down in about 30 seconds. I live in Southern California so its not really that cold out still
Be advised that your wife's car, unless a 1997 camry, works differently, especially if it's newer, you can't really compare.
still, this is a relatively new problem. what should i do?
Clean the IAC, known issue for Toyota’s.....
Just disassemble it and clean it, right near the throttle body.....
