So my 05 Evo hesitates when I get on the gas. The car bucks and hesitates at wide open throttle right at 3000 rpm. My first thought was boost leak, so I installed an Injen intake and IC pipe kit. The problem did not go away so I changed the spark plugs. Still there. Then, I installed a forge waste gate actuator. Still there. I put in an AEM 380lph fuel pump, still there. Turbo blades spin freely. The pipes pass the soapy water test. Boost gauge hits 7 and creeps to 9 when I ease into boost range but the whole car is a hot mess when I get on the throttle. Before the problem started, I was hitting up to 20 pounds of boost. The only thing I did with the car before the problem was disconnect the battery when I left for a six month period. If I can't get any better ideas, the next step I plan to take is a reflash, or pro tune. Oil is changed regularly. Can't think of anything else outside the ECU that could be the problem.
I have been experiencing this problem for quite a while now. I already know that most ppl are going to say boost leak but I don't think that is the problem.
Any help I can get would be greatly appreciated.
Thank you,
Quentin.

 

Have you checked your spark plugs? Might be about that time for a replacement.

 

Yes. I thought that I wrote that in my original post but I guess I wrote injectors instead. To be clear, I did not change the injectors, but I did replace some ngk's spark plugs (old) with some iridium pre gapped ones (new) from napa.

 

Regap your plugs to .020-.022 and try again.

 

Plugs are properly gapped. No joy.

 

So is the car tuned or not?

Im sorta confused as to your thought process here...why throw more parts at it in hopes that they will fix the problem? The correct process is to get the car operating properly first and then you can switch some things up.

The more you change, the harder it is going to be to identify what is the culprit of your issues.

Personally my $ would be on the tune. You put in a larger fp which has probably richened things up. The factory tune is already rich to start with.

I see you are from Washington. Im not sure the geography of the state but I would recommend you take the car to English Racing. They will get your car sorted out and running properly for sure.

 

Its the tune, your hitting too high a load and the car is shutting off-- a tune will fix that. You cant change the velocity or the amount of air into an engine and expect all things to remain the same--

 

Well, I replaced the piping because I thought it was boost leak. I replaced the WGA and spark plugs because I was trying to eliminate what I thought was a failing part. I do want to get tuned at English racing, for two reasons. 1st: I'm thinking that the air fuel ratio or something in the map is the problem, which ER should be able to fix. 2nd: I am trying to build up to about 425 WHP. Can't hit that without a tune. There are still more things I need to do before I drive down and get this done.
I guess I was just hoping that someone on here had a better idea of what it might be. I am trying to avoid the cost of tuning until the car is ready.
I am still hopeful that someone here can point me in the right direction.

 

When you did the boost leak test, did you check the throttle body seals? and did you check to make sure none of the small rubber vacuum lines popped off (there's one in particular behind the throttle body that is known to pop off)?

I've found leaks at the throttle body seals, the injector seals, PCV valve, the blowoff/diverter valve, and vacuum lines have popped off...

 

I did not check the seal at the throttle body. And I did not know there was a vac hose behind it. I will go look for it now. Thanks.

 

Throttle body seal is good. All lines are on properly. Still no joy. The tightening nut on the WGA slid down. Gonna let the car cool off and tighten it. When I put it on I set the bolts and pulled the actuator on very tight. Is there such a thing as too tight WGA? The valve operates.

 

The problem presented itself before I started replacing pipes and such. The only way I could think of that the tune would be the problem is if there was something altered on the map before I bought the car that I reset when I took the battery out before I went on deployment (6 months). The stumble started small and grew worse as time went by. After checking all lines and replacing the WGA. It has become less prominent. I am going to pull the spark plugs, again, and check the gaps. I really want to avoid the tune until the car is ready. ( 02 pipe, exhaust manifold, down pipe, and wide band.) but I don't want to keep throwing money at this car until the problem is fixed.
Vicious cycle...

 

get new spark plugs and get a good tune

 

I can't believe you starting darting tons of aftermarket parts at your vehicle to try and figure out a problem that you haven't even diagnosed properly. This drives me crazy. You think a crap load of aftermarket parts will fix your vehicle??

 

Did you try cleaning your MAF? Also what bov are you using?