..I've been getting really high rpms (~2000-2200) on start up a couple of times..... and when this happens it normally does not come down... I restart the car and it is better....

Does anyone know the cause for this???

Thanks in advance

-Sergio

 

do you have any mods on the car (intake/exhaust/y-pipe/supercharger/etc...)? is your check engine light on? have you changed or disconnected the battery lately?

-V

 

You might have a bad a/f mixture or you have a bad thermostat.

 

I have the mods listed below....I haven't disconnected the battery lately, and no check engine light....

How would I confirm a bad a/f ratio or the bad thermostat....???

 

My moms nissan quest does the same thing when u start it up the rpm's are up there at 2000 - 2500 and the check engine light has been on in her car what do u think it is???

 

This is likely not a bad thermostat. If the engine runs consistently too cool or too hot, then the thermostat is probably shot. If the engine comes up to normal operating temperature in a few minutes (and remains there) the thermostat is probably fine.
2200 RPM is not abnormally high for cold engine startup. However, if the engine speed at idle doesn't come down from there, then that is something to correct or have corrected.

 

I believe my normal start-up rpms are usually around 1500 dropping down to about 1100 until it gets to operating temp...

However, when this happens it shoots up to 2200 to maybe 2500... only has happened a few times... And it doesn't come down. It appears as if it gets stuck at that rpm....

what could be causing this????

 

the best it to pull the MIL diagnostic code. it's probably a bad sensor, and the car is defualting to some fail-safe mode where it keeps the car running, thereby giving it's best guess with a high idle.

-V