Basically the problem is that under full boost, it breaks up, mostly after shifting and dumping the throttle. It will stutter just a little bit through the powerband of the first gear(just enough to notice it) then after changing gears it will break up, pretty hard, it actually makes the whole car rock back and forth violently. But if I lay into the gas, after changing gears, it seems to do fine.

So here is the story:

I have been having this intermittent problem with my Evo and its been coming and going since November of last year.
I had originally thought it was a batch of bad gas that I had bought, so I emptied the fuel tank, and cleaned it out. - didn't fix anything
I changed fuel filter and the fuel pump. - still nothing.
I changed the plugs. - nothing.
Cleaned the MAF. - no improvement

So with a little frustration I gave up on it, and just daily drove it, since it only broke up under full throttle.

A couple months later, (Feb. or Mar.) me and a friend of mine were taking another look at it, and all we did was put a little dielectric grease on the plugs. and IT WORKED.

I drove it probably about 3 months and did a boost leak check on the evo. everything was good but it started breaking up AGAIN.
This time I felt like it was the ignition, so I bought some new coilpacks, plugs and wires. And nothing worked.
I cleaned the MAP sensor and it fixed the problem, but only fixed the problem for about 2 weeks or so. Then it came back. since then I have bought a new MAP sensor and I checked the pulse on the injectors and still have the same problem.

And at this point I am out of things I think I can do...
any help/input will be appreicated , Justin.

 

No cel? Do you have any way of checking the voltage while it does this? A bad ground or an alternator on it way out could fail under a larger load (boost)

 

No Cel, and I don't think I have a way I could check the alternator especially at full load. But I will take a look at all the grounds and clean them up, thanks

 

Stock tune? What gas? What boost level? What plugs and gap are you using? Can you log your car for us?

 

It is not on a stock tune, it was tuned before I had bought the car in may of 2010. I actually have been thinking that it may be the tune, because I did buy the car in Alaska, and now I live in North Carolina. Also alaska only sells 90 oct and now I'm on 93. I'm running 18 psi and a .020 gap on ilfr7h plugs.
I just want to make sure it's the tune 100% before I actually do it, because I really don't have much spare time and money just for it not to be the problem

 

18 psi and 0.020 doesn't seem right I think that is too close of a gap for that boost I run that gap at 30 psi I would think 0.024-0.026 would be closer? I think stock is 0.028? Not sure that's the problem just throwing that out there. I would also either retune on 93 octane to get more power or use 91 octane if it's available to you for the tune the car currently has.

 

Well I just never gap the plugs when I get them because it says don't gap them and they are always at ~.020

 

so it was tuned in a cold area with lower octane. now youre using a different octane in a warmer area. sounds like engine knock from the temp change?

 

a tune is not something to try to skimp and save money on.

a tune is essential to the long-term health of your motor. you should get tuned ASAP by a reputable tuner. If i'm wrong, evom will correct me, but, I would never take the chance I think you're taking.

 

looks like you have your answer.

 

^ yes it does. I'll just leave the car in the garage, until I can afford to get a tune for it. I appreciate it guys