when i start my car and its been sitting for a while (like 4 hours+) and its really hot outside like +20 degrees C it will rev up to like 3000 and stay there for a couple minutes unless i tap the gas, at which point it drops to a more acceptable ~1000 until it warms up enough to go to the normal ~700

and when its really cold outside like -15-20 degrees C when I start it it will rev up and down between 700-1500 a few times then die out, unless again I tap the throttle at which point it will take an acceptable higher idle like 1500-2000 and slowly drop down until it is warmed up.


what the heck could cause this?

 

Some things to consider:

1) Starting the engine with the transmission in gear will bypass the accelerated warm up system (3k RPM cold start).
2) The ECU uses feedback from the water temp sensor (back of water pump housing) to adjust the amount of fuel injected. At colder temperatures, more fuel is injected than when warm.

 

hmm i didnt know that about the accel warmup thing. i was wondering why it only did it sometimes lol

either way, it only does the accelerated warmup when i dont need it to, like when its really warm. in the wintertime it will either idle around 1000 or "hunt" then stall, unless i tap the gas.

 

The AWS system is commanded by the ECU, which in turn gets its temperature information from the water thermo sensor. The ambient air temperature has less to do with triggering the AWS (3000 rpm) than does the coolant temp.

There is a procedure in the service manual for checking operation of the AWS.

The hunting/stalling idle could be a vacuum leak, or a mis-set idle mixture. It could also be a problem with the BAC valve, although that seems less likely.

 

i dont see how a vacuum leak could cause that if simply tapping the gas even the slightest amount upon starting it will completely prevent the issue, or stop it if it's already running and happening

 

The 3K startup and then 1500 RPM idle is proper behavior.

If the car has a tendency to stall in cold weather, check for vacuum leaks and make sure the TPS is properly adjusted. Also, when is the last time it had a basic tune up including plugs and wires?

 

nah once i tap the gas its totally fine. not a big issue its just weird and im wondering why it might do that
just changed the plugs a week or 2 ago. wires look ok