idle problem

[puty72]

I recently discovered that all my gas guzzling and lack of power problems were due to the coolant temp sensor i thought was my gauge sending unit being disconnected. Well anyways i got a new sensor and installed it and my check engine light went away and my truck drives much better. The only problem is now it idles high at start... say 1500rpms. It didnt do this before when the sensor wasnt hooked up so why now?

 

[martin]

It's supposed to run at high idle for the first couple of minutes to get the cat up to temperature as quickly as possible.

 

[jhammel85]

It's supposed to run at high idle for the first couple of minutes to get the cat up to temperature as quickly as possible.

+1, As long as its doing this cold and about 850 or so if you are driving an automatic, you're in good shape

 

[disciplerocks]

^+2. You can also try unhooking your battery for 5-10 minutes then starting it and let it idle and let the ecu relearn everything. or you can just keep it like it is and it will eventually do that on its own.

 

[kimcrwbr1]

+1 on resetting the computer and you can get a cheap code reader to erase the memory also. Erase the memory and disconnect the battery for 1/2 hour the run it at medium speeds for 20 minutes or so and run the codes while it is still up to temp and see if it throws any codes. It can take a few good warm up cycles to set new values. You need to reset the computer after cleaning or replaceing any of the sensors so your not running on old values the sooner the better. The memory will not affect the operation of the engine but the hard faults need to be corrected as they directly effect performance.