Runs horrible when cold, then fine after about 10 min of idling, what could it be.
 

okay my car has been acting funny for the last few days and it just keeps getting worst. when you start it up, it runs for about 5 seconds, then stalls out unless i keep my foot on the gas. when you restart it, it idles fine. but then as soon as you give it gas it stutters and feels like it wants to die. if i let it sit for about 5-10 min just idling, then it runs perfect. i changed the plugs and wires about a month ago. the only thing i could say that ive done differently was switch premix for about a week. the previous owner was using polaris ps-4 plus. i ran out so i used valvoline tcw3. but i returned to the polaris as soon as shipment came. besides that nothing else changed on the car. what can it be? i have a vid to show how its acting.


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look for a vac leak first. do you still have your cold start wax?

not sure what that is? it doesn't fast idle tho, it starts and idles at normal rpm.

coolant temp sensor

on cold starts (below 68 i think) it bumps the idle to about 1700 to warm up. now it will dump the fuel for that idle and if your thermowax s not working or miss adjusted (2 screws adjustment) it will do that. mine was going that too at warm starts and i found my adjustment out. look at the fsm for cold idle adjustment. this is also dependent on the coolant temp sensor as it reads it as well.

is there a way to check it?

this explains alot. it has been acting up ever since the weather changed now that i think of it. my idle doesnt bump up to 1700 when its cold, so i will look into that. thanks!!!

The voltage at pin 2I (Green/White wire) of the ECU will tell you the condition of the Water Thermosensor as it should read 2 to 3 volts w/a cold engine and .4 volts fully warmed with key to on.

The car should rev up to 3000 rpm on a cold start if the coolant temperature is north of 62 degrees or so and it will last for 17 seconds. After this quick rev the idle should drop down to about 1500 rpm or so until the engine slowly warms up and as it does the idle slowly drops down to a normal 750 rpm.