My Evo IX was tuned last Sept. with minor mods, had been running fine. Recently it has started to hesitate, after driving a few miles crusing at 60-65 in 4th and 40-45 in 3rd it starts hesitating until I adjust the throttle. The exhaust is also popping more off throttle. My wide band is dropping into the 13's when this is happening. Do I need retuned, can it go out of tune?

 

Change your spark plugs.

 

I changed plugs 6000 mi. ago. I had pulled them to take a look and recheck gapping. All are gapped at 0.022, two plugs are more light cocoa in color and two are more light gey in color. Coil?

 

what fuel are you using? +1 on the plugs.... check your coils
if its warmer might be an issue depends on your fuel well at least here in vegas with e85

 

93 octane, going to test coils. Normal for coil to go bad by 51K?

 

Is the SES light on? If so, what codes?

 

bump. my car has slight hesitation when warming up from ~2.2k to 3k. Plugs were changed very recently (2k miles ago). although my AFR's were self tuned to 15.6 while not under boost.

 

No, no SES light. No SES light came on when it was hesitating before I changed plugs 6000 mi. ago. It was running great until last week. No hesitation during acceleration so far, just cruising it starts, same as before I changed plugs only worse. I'm hoping it's just a coil, but don't know yet.

 

try to see if the plugs were loose (not torque down)

 

Loose plugs, I wish, I've had them out twice this week, they be tight.

 

That happened to me but it stopped like 2 weeks after it started dont know what it was :-/

~Sean

 

When I was given Evo 8 plugs my car hesitated really bad due to the plug being too short for an Evo 9 head.

Car drove, but was just very uneasy and holding constant throttle resulted in a weird hesitation that would go away after giving it some more gas.

I think it was the colder, shorter plugs not able to warm up properly, but i drove all of 4 blocks to get the right plugs so who knows if it would have got better.

Learned my lesson about the Evo 8 vs 9 plugs though Won't be doing that again.

 

Wow, mine had been doing it for 2 weeks, finally took it to have it checked yesterday. Was on empty so i got fuel before dropping off. Car ran fine on the way there. The tech. could find nothing wrong with the car, took it for 3 drives, 40+ miles and it ran fine for him. Picked car up ran fine on the drive home and had no issues today. Bad fuel/water?