I have been having occasional trouble starting my evo 9. On a cold start if I leave the car sitting for a few days it will start right up. If the car is warm and I turn it off and then back on while the car is still warm it starts up perfectly.. The problem arises when I leave the car for a couple hours and then try to start it. The car will crank but won't start. Occasionally I can get it to start by pressing the gas pedal.

Anyone know what could be causing this?

 

This is similar to leaky injectors back in the rx7 turbo II days. Hope im guiding you the right direction. But should check spark and fuel when it doesnt want to start.

 

Hmm I'll give that a try. Could a faulty sensor be causing this?

 

May be vapor lock.

 

I've read where water temp sensors can cause bad start up/idling issues. Swap these out with a friend to see if that is causing the issue. Could also be a bad FIAV sensor, but your car is fairly new compared to mine (1995 Evo 3).

Also, make sure your couplers are all on correctly. This happened to me once and I found out the hard way. Squeezed the car and the coupler popped right off they are #forevertight now.

It could also be a small vacuum leak in a vacuum hose.

 

This might be the problem because my tuner said I was having a cooling issue when my car was on the dyno a couple weeks ago. I haven't had time to figure out what it was yet. I was going to replace the thermostat to see if that helps. I'm getting a new iac to see if that is the problem. I've been getting erratic idles while driving as well. If that doesn't work I'll try the water sensor as well.