Hey gents, I am having a problem with my 08 Evo X. When I give it full throttle, my car stutters and does not give full power. Also my A/F is at 14 or so while it is stuttering. I just changed my spark plugs and that helped a little. Thought it was the tune but went back to a tune that I had no problems with and nothing changed. The car has 35k miles on it and I have not done the 30k maintenance on it. I am not sure if that would really cause it. My friend and I think it may be something with the fuel system(i.e> injectors, fuel rail or filter) since I go so lean when I give it full throttle but we are just guessing. What do you guys think it could be?

Cliffs:
Car stutters at full throttle
changed spark plugs and its not the tune
need to do 30K maint(car has 35K miles)
think it may be injectors, fuel rail or maybe fuel filter but thats just a guess.

What could it be?

 

Did you already rule out your clutch? my clutch went out around the same time.

 

I was reading that this was a common problem with the Evo at full throttle. Have you brought it in yo Mitsu to have them upgrade the ecu? I read somewhere that the upgrade to the ecu fixes this problem. Someone else chime in if I am wrong.

 

I had a severe stuttering all of a sudden on my Evo 9, and it turned out to be the spark plug coils (ignition coils.) They weren't firing efficiently, therefore essentially missing. Replacing them solved it for me. But this may be different.

 

What spark plugs are you using? I know you have a 9 but the brand should be the same for the X.

 

I did some more research and found out that the fuel relay in the engine bay can be the cause. Took the relay out and shook it and it is bad. I am going to replace that one that makes noise when i shake it and 2 others just to be sure.

 

You haven't read the threads on the fuel relays? Yes, make sure they are the right color...

Also, not sure Evo 9 and X plugs are NOT interchangable.

 

No I haven't had the time recently. Usually I read all the info like that but I have just been to busy and slacking on my forum reading.

 

right plugs and gap accordingly. 0.022-0.024

boom-done.

 

That was happening to me last summer. It turned out to be a disconnected vacuum hose that connects to the fuel pressure regulator. It was popping out of place every once in a while, so i used a zip tie to keep it in place and it hasn't happened ever since. Might not be it but couldn't hurt to look.