Evo 9 stutters when accelerating
 

I know there are alot of threads about this, but none are really what im looking for. When I start to accelerate, the car stutters fast. I tightened all the clamps and checked for anything loose, which nothing was. I have been having this problem for a while now. Before I changed the sparkplugs, when I went WOT, the car had one big stutter and then carried on. Now after the sparkplug change, I accelerate hard and the car has a fast stutter through all the rpms. I don't know whats happening, and any help would be greatly appreciated. I don't think it is a boost leak either.
Also the car starts to stutter at 3500 rpms. Also I just put in some fuel injector cleaner, I'll update later.

Evo 9 stutters when accelerating
 

What plugs did you install? What are they gapped to?

Is it a misfire feeling, or a shudder? Usually when I see cars with a shudder issue, I'll start by checking the transmission and axles.

I bought the oem gapped autolite iridium xp's but I don't think it's plugs cause I had this problem before I changed them. Although I'm not sure why changing the sparkplugs would have changed how the problem behaves. Sorry if what I'm saying doesn't make much sense it's just hard to explain it.

I've never had an issue with misfires so I wouldn't know if it's that. Basically once I hit 3500 rpms and keep accelerating , the car starts to start and stop very fast. I'll try to take a video so you see what I mean

check the coils

Welp sorry guys, I just pulled out the plugs and checked the gap, and they were close to .05. I brought them down to .022 and the car works flawlessly. I guess I shouldent of taken the autozone guys word when he said they didn't need to be gapped and my lack of knowledge about gaping. I'm relatively new to the evo, and I didn't even know gapping was a thing till now. :eek:

I don't think the oem plugs are autolite. I like to use ngk plugs over denso. Also just so you know, after driving awhile the spark plug gap does change so it's good to recheck them once in a while. You will notice it under wot acceleration. That's what happened to me. Glad you found your problem and never trust any parts rep.

Always gap your plugs. I figured you were blowing out spark. Also, check the plug length to be sure you have the right plug. Auto parts does like to give you VIII plugs, which don't reach as far into the cylinder.
Next time you may wanna go with NGK or at least Denso. Not sure I'd trust Autolite. I didn't even know they made a plugs for our cars LOL.
Give them a try, though. Let us know how they do. {thumbup}
Glad you found the problem!

I had a weird misfire issue (not saying that yours is the same) but it also showed up as an injector failure CEL after a short time. After buying and installing a second set of injectors to eliminate that as a possibility of the cause (needed an excuse to get them anyways) it ended up being the resistor pack for the injectors that blew. Funny thing about it was Mitsubishi said the resistor pack isn't on an evo ix even though my mechanic was looking right at it and had already looked up the part number online and had tested it with a multimeter to see it had failed. Sad when the OEM can't even give you the right info. Anyway its an easy check in the event that everything else checks out fine. Mine gave a bad stutter and a huge drop in response because it was basically running on 3 cylinders

Similar issues here but gap still looks like .020 on mines. I'll do a compression test tomorrow .