Car won't start once warm up
 

Hi Evom

Need some help to diagnose my new Evo 8 MR. It's tuned on E85 and HKS Vpro. The car starts up just fine when cold but once you drive it for 15+ minutes and let it sit for more then a few minutes, it won't fire. It'll turn over and crank but it won't start. But on the other hand, if I drive it for more then 15+ minutes and turn it off and then quickly crank it, it starts fine. It's only when I leave it for a few minutes that it won't start.

Now if i let it cool for about 20 minutes, it'll start right up. I'm thinking bad cam sensor Or coolant temp sensor. Thoughts?

Quick mod list
SD
COP
E85
HKS FCON Vpro

Thanks in advance

Update 9/22

Check spark plugs during time it's unable to start - they work
Replace coolant temp sensor - same issue
Replace cam position sensor - same issue
Check fuel by removing injectors and priming car - no fuel

So there's something that is stopping the fuel during the time it's in operating temp and turned off. The car does have a double fuel pump, perrin fuel rail, fic 900 cc HI injectors, and the resistor box has been bypassed correctly.

So I already know that the injectors doesnt fire when the car warms up. What can cause this? Again, I have FIC 900cc HI running the resistor pack bypass, Perrin fuel rail, BR double pump, oem FPR, running SD.
Thoughts?

Update/Resolution

turns out, car was not holding pressure (double fuel pump). shop was able to fix this.

Ethanol likes to vapor lock. Are you running a fuel pressure solenoid?

Yes I am. I've had an e85 evo previously and its never done this before.

check what I told you incase it was overlooked.

Sean

Here's Sean sent in case anyone has thoughts.

"Odd we never had a starting issue.

Please make sure the resistor pack for the injectors has been bypassed since you are running high impedance injectors that can cause an issue.

Sean"

I'll check in a bit to make sure that it's still bypass. Not sure why it wouldn't still be though.

Would the COP be any issue?

Test your coolant temp sensor. Should be the easiest to troubleshoot.

how can I check that? Multimeter? the temp sensor inside the car show's the correct reading and never over the half mark when the motor is up to temp

I just checked and the resistor box is gone and has been bypassed correctly. Any other suggestions?

Yes a multimeter. Temp sensor relays the readings to the ecu, not to your dash. The dash one is different. Not sure on the Evo, but on my DSM they were both on the thermostat housing.

Easiest way to test is to remove it, put it in a vise, hold a lighter up to it while you have a multimeter hooked up to it.

At 20c it should read 2.1-2.7k ohms.
At 80c it should read .26-.36k ohms

That is according to this .pdf I found on the net (Section 13-4 is where the info is)

http://www.evoscan.com/manuals/Evo6/...l/EV6_XE13.pdf

Pretty much as the sensor gets warmer you should see a nice steady drop in the ohms.

EDIT: Make sure when you reinstall it that you put some sort of sealant on the threads to avoid leaks. I usually use that white tape on the threads that plumbers use.

In my experience when the coolant temp sensor is faulty, or unplugged during cold start it will not fire.

This sounds like an issue we had on our hmmwv ij the military when in iraq. They would start fine and run fine untill you turned them of then they wouldnt start untill they cooled down. The reason was the fuel pump shut off solenoids would crack from the heat and expand so the solenoid would work to open the checkvalve to decrease the fuel pressure during start till it cooled down. So to me it sounds like your cars fuel system is in a vaccum or vapor lock. Not sure if evos have a fuel solenoid or not

Not sure if it's consistent with Evos, but on many other cars I've worked on if you have problems on warm starts but not on cold starts often times you may have a failing ignitor that's getting too hot.

or that the ignitor is not firing at all. i'm going to check with the cam sensor and get back to all of you. in the mean time, continue to throw me some ideas.

Drove the car for about 25 minutes. Left it for 10 min and tried starting it an does not fire. Took the cam sensor out and cleaned it. Bolted it tight and it tried starting it and she started right up. I hope that's the problem and hopefully is now fix. But I will update if it happens again. I Will probably replace it with a new one to make sure it's good.

You should really be testing this stuff with a multimeter if you want to get to the root of the problem.