Hey guys having a little problem with my evo 8, seems like when I get into high boost my car starts to spit and sputter or miss fire, it does it when the car has set for more than like an hour and a half, and them after I drive it for maybe 30 mins it tends to just stop doing it and pulls fine, I have a little video but you have to turn your VOLUME UP to hear it, btw the beeping noise is coming from my boost gauge, the gauge reads to 30 psi and I'm dyno tuned for 24 so it reads it as "high boost". I'm thinking missfire, my car is fully dyno tuned just for a head up. The spark plugs are ngk 1 step colder and were gapped and installed less than 3k miles ago by a reputable shop, same with plug wires, were replace about 3k ago, maybe coils? Gonna try to swamp with a friend tommarow to see, some people say coils don't go bad, they either work or don't so who knows? Anyway thanks for the help guys! - See more at: http://s304.photobucket.com/user/rya....t2ENbq5s.dpuf

 

If you are tuned for 24 shouldn't you be running 24?

 

The car spikes 24 and falls to about 19. If that's what your referring too

 

Fuel cut because of over boost??

 

did you replace the plugs with the SAME EXACT ones you had while you were tuned?

 

I highly doubt it's fuel cut because I'm tuned by reputable shop unless I have a bad fuel pump or clogged injector and I have not changed the plugs since they were installed and tuned on, which was about 3k miles ago

 

You need to pull the plugs and check them for broken electrodes etc. Just a physical inspection. Thats a start--if you have detonation and you keep boosting your going to find a rod under your car.

 

Sounds like fuel cut to me. (from what it seemed like in the video)

What fuel pump are you running? and how long after the tune did this start.

BUT since you said it goes away after driving awhile I doubt its fuel cut because of over boost.

I had a sputter once similar to this but not as bad and turns out I was running way to rich and I took it to my tuner he retuned it and it was fine. He also said it can be caused by running to lean (obviously) but in my case I was running to rich. Tuners make mistakes sometimes even the good ones if you cant find a physical problem I would request a retune for no charge.

 

My afrs look fine, already took it back to the tuner before and he logged and and made minor adjustments but found nothing, this starte the day after I got it tuned and hasn't stopped since, we pulled the plugs after it had been hesitating for about a week and they looked fine, I will pull today and post an updated picture, I'm on a stock fuel setup, stock injectors and fuel pump, thanks for the reply guys! Keep me coming!

 

Anyway so here they are guys, just pulled the plugs, look fine to me but lmk what you think, they are gapped at .026. - See more at: http://s304.photobucket.com/user/rya....URY35WOt.dpuf. - See more at: http://s304.photobucket.com/user/rya....E8gY0hxy.dpuf

 

Make a quick pass for all the vacuum lines as well including egr and fpr. Check them all with the car running.

 

My car was doing the same thing. First wot full boost 1st or 2nd gear pull I would feel a miss. The very next time I would do it it would be gone. My thought was the ecu seeing a knock and pulling timing.

 

Your on a stock fuel pump pushing 24psi? I had to upgrade to a walbro 255 because my stock fuel pump wouldnt push 20. Just saying. What is your awhp. That could be it.

If all else fails or no one solves your problem by the walbro 255 fuel pump kit I think its on sale for like 70 bucks? and takes maybe an hour tops to install by yourself.

 

Dang, my fuel pump does whine a little but I've heard it normal on our cars,although I don't know what fuel pump is suppose to whine, but yea I also thought 24 psi was a little high for 24 psi, if they are only 70 bucks ill probably install that next.

 

Regardless if it helps the issue which I doubt, fairy good bang for buck!