I have a 2003 VIII with 262 cams tuned by Jms on stock turbo. The car was running great but about 4 days ago it started missing. It isn't a consistent miss it's off and on. At first I noticed it while cruising at 65 mph down the freeway. The car will be running fine then it is like you turned off one of the cylinders. You can let of the gas pedal and press it back down and it will do fine for a while then a little bit later it will do it again. The car idles fine no miss at all but if you hold a steady rev above 4500 Rpm it misses. When it misses the exhaust sounds like a Subaru. If you continue at whatever rpm the car misses at the miss will continue even if you raise the rpm. But if you just let off the pedal and right back on it will temporarily go away for what could be minutes of longer. I changed plugs and wires yesterday and it did not help. Plugs are bpr8es with at 26. I'm an Evo newbie. Any help would be very helpful. Thanks.

 

search.. from my recent experience, coils, wires, plugs

 

Evos run rich, take a look at your plugs NGK BR7ES gaped at .023. When was the last time you did an Italian tuneup?

 

As said above try changing the plugs to start with, if this does not cure it see if any fault codes are stored (P0300).

 

i would double check timing. make sure everything lines up. also check your cam and crank angle sensors.** there is also a tsb for transmission input shaft wear. causes pcm to mis calculate signal and cause car to misfire. tsb TSB #06-13-004

 

^^^^Sure do the hard stuff first^^^^

 

Turn off the p0300 code in the ECU.

Also, your dash need a new bulb in the CEL location.

 

well ive got an 03 and for a while i was bein stuck with the dreaded p0300 code at cruising speeds in 5th gear around what speed your describing, you can tell it was makin the ecu run funny cuz when it would do it it my cruising afr would be between 14.7-15.2 and all of a sudden it would fall flat on its face and go into the 11s sometimes high 10s.....just have that p0300 light turned off with the ecu your tuner should be able too. What ive done to get around it is unless im passin people while cruisin on the freeway boost up to about 10psi hear and there to get some of the extra compressed air in there out. and try to keep throttle about 20% while cruising, it takes practice but that should help keep the misfire from happenin.

 

You ever figure this out, I am seeing the exact same thing, already changed the plugs and wires.

 

It was the plug gaps. I had to play with them. My car with ended up liking 24 thousands. Runs like a top.

 

nice, i will be regapping mine tonight!