Hey guys, so I'm having an issue and I'd like to see if I can diagnose the problem with some help before I take it to the shop.

I was driving home and all of a sudden my Evo started sputtering and hesitating to even run. It almost stalled at one point. Luckily, I was around the corner from my house when this happened so I made it home. I checked the spark plugs and all seemed fine except #4. It was loose and covered in black "stuff". I re tightened it and ran the car around the block and same thing was still happening.

Any help is appreciated.

 

Hard to be sure just from the description, but these kind of symptoms are very common with the ECU is getting bad airflow readings. This is most commonly caused by either,

(a) Most common: An intake hose coming off; usually on the high pressure between the turbo, through intercooler and into the throttle body.
(b) The MAF sensor has become unplugged

I would suggest checking all your intake piping and MAF connector.. also on my Evo 7 particularly once the cold side of the intercooler came off but because of the factory mountings it was only JUST coming off.. and basically just blowing apart on boost.. so was not obviously disconnected on first inspection. Aftermarket systems without brackets/supports usually come off more obviously - so double check any stock stuff.


If it's not the above then you probably need someone more technical to diagnose the issue.. hopefully it's the above as it's a super simple fix. :-)

 

Thanks, I'll give all those suggestions a shot. Although, I did check all the piping and everything was nice and tight. I appreciate the suggestions tho

 

How is start up and idle? Power? I just had the same issue and it was a blown headgasket.

 

Do a compression test, quick and easy.

 

if the plug was loose long enough, your trims may be off. i'm not sure enough to have it run that poorly. the plug may be fouled. try a new plug while you're at it.