When I'm driving at higher RPMs (5000-6000) it feels rough. It's hard to describe like it's hesitating and then going and then hesitating. Once I shift its fine but I can't figure out what's wrong. Anyone have any idea what it could be?

 

Does it feel like a misfire?

 

yeah sort of, I just changed all the plugs with OEM plugs but the car is on jack stands dealing with other issues so I havnt had a chance to drive it yet.

 

how did the old plugs look and were the gaps in line?

 

This was the first car I have ever changed the plugs on and it surprisingly was easy to do. The plugs I removed were burnt. Idk what bad plugs look like though. And I bought a gap checker but the gap was barely big enough to check. I assumed they were the correct gap.

 

They should be gapped to .020"-.022", you need a feeler gauge set.

 

Well the new plugs got rid of the misfire code but the hesitation is still there. It almost feels like there is not enough fuel or to much air. It's only when I get over 6k rpm.

 

I had this problem recently to the point where I couldn't even go past 4000 RPM and it would behave like a boost cut or leak.


It would only happen after cruising at constant speed on the highway and I would step the accelerator a little or downshift and try to go faster.


It ended up being my MAF.

 

Switch the fuel pump relay with the horn relay, if it fixes it, get a new fuel pump relay.

 

How are you guys offering so much advice when he has offered no information about his car?

Is it new?

Modded?

Stock?

Did he just get it?

Has it always run like this?

There are a million reasons that could account for this, chasing suggestions without providing any info will just have you chasing stuff and wasting money and time imo. Give us information and details, then you get good answers.

Good luck

 

Could also be detonation and the ecu pulling timing.

Is it tuned?

 

A little history on the car:

Its a 2008 GSR with the following mods:

Cobb upper IC pipe
AMS intercooler
AMS down pipe
Cat delete straight pipe
Spec D cat back exhaust
Synapse BOV
Sakura intake

I got the car about two weeks ago and that's all the mods I can SEE. I know it has a newer clutch also and I just put in new OEM plugs.

 

I have no idea if the car was previously tuned. With all the add ons done I hope it was.

 

First stop - get it protuned

If no good ones in your area there are a ton of good e-tuners. Chet Rickerman, wtftuned, I believe Kozmic Motorsports might e-tune

Good luck, but a tune is your issue. I'd go easy on it and stay out of boost before you get it checked.

 

Do you think a Cobb app would be beneficial to me considering I don't have many Cobb products?