for a while now the teg takes forever to warm up. driving to work like 15 miles away the temp only reads a little past the starting point and car doesn't seem that powerful at top end. could it be a bad thermostat like stuck open? is this bad? car is turbo and using an aftermarket civic radiator btw.

 

could be a bad theromstat...you could also have air bubbles in your coolant system.try replacing the thermostat with a new one..their cheap

 

haven't replace the thermostat since i got the car like three years ago and haven't change the coolant for almost a year and a half. will this cooling problem affect the engine? seems my vtec doesn't work properly when it is cold.

 

yes your coolant systems affects your vtec alot...vtec only engages to full potential when your car is at normal operating temps...like i said best way to go on this is replace the thermostat...and bleed your coolant when you install the new one...check for leaks anywhere...that could also be a cause

 

I thought for sure Vtec engage when there's good amount of oil pressure not COOLANT temp..Maybe I'm wrong...

 

nope V-tec only engages once the motor has warmed up.

 

correct vtec only engages when the motor is at normal operating temps...if not it will cut off

 

ur tstat is stuck open..happen to my car a few months ago