Okay, I'm sorry, I tried to find an answer in search but I didn't, so if this has been answered already please direct me to it.

I have a 2005 Evo 8 MR. It has started giving me trouble with accelerating. When I try to accelerate it lags (for lack of a better term..). I'm not trying to accelerate fast, just normal acceleration. Sometimes in 5th at 55-60mph the car will feel like it is starting to slow down. In both cases the boost gauge will immediately go to around 0.5, but it takes a bit for the car to begin accelerating when it does the turbo gauge goes back to 30. The rpm gauge does not go up while this is happening both the speedo and tach either decrease or remain the same. Mechanic told me to check the plugs and clean the injectors. Plug gaps are good.

What would cause this?

Thanks!

 

Throttle position sensor maybe? if it's not doing anything weird, but just not responding to throttle input that would be my only guess

 

Thanks!! I'll check that today. It hasn't thrown any codes so hopefully it doesn't need to be replaced.

 

Since your boost gauge reads basically 0 that tells me your throttle plate is opening ok otherwise you would be in slight vacuum. You post is confusing though. So under "normal acceleration" you are saying your boost gauge goes to 30psi? Sounds like you are going WOT to me. What rpm are you at when you try to accelerate? Is the car modded? What turbo? Sounds like normal turbo lag to me. Maybe you need to downshift to 4th to accelerate instead of leaving it in 5th. Is this your first turbo car

 

haha Yeah, I'm not great at trying to explain things. :/ As far as I have seen it is totally stock. It's not my first turbo, I had a WRX before and have had my Evo for 4 years. This is something it hasn't done before.. Never had turbo lag that lasts 5 or so seconds.

Okay, Let me try this again. So on the turbo gauge the needle rests at the bottom left when I'm at speed, not accelerating. (That's what I meant by 30.) Not WOT.

Basically I give it gas and it feels almost like driving with the brakes on, it doesn't accelerate, at all. When that happens, the turbo gauge hits 0.5, the tach and speedo don't change. It will stay that way for a few seconds (3-5 or so) and then it will finally slowly accelerate and the turbo gauge will drop back down. This is when I'm just driving on city streets. Even if I really put my foot into it, it won't accelerate for several seconds.

The "5th gear" thing will happen in any gear, I just used 5th as an example. I'll be driving (over 3000 rpm in whatever gear) and it will start slowing down, feels kind of like breaking, and the turbo gauge will go up to around 0.5 but the car won't respond for several seconds and then it will accelerate back to where it was.

It isn't throwing any codes, so I really don't know where to start. I have never had an experience with bad gas, but my husband thought maybe that was it? There is no misfire or shudder, just feels like it would if the breaks were applied.

 

Do a boost leak test. Even though your CEL isnt on, try and pull codes anyway.