Sparta

Hey guys I have had a very weird problem with my 2009 GT. History: I got a K&N CAI installed on Saturday, drove to a town called Schulenburg (about 2 hour drive) to go pick up my dad. Filled up there at a "no-name" gas station then proceeded to drive home. The car sat all day Sunday. Monday I drive to work everything is fine, on the way home from work on Monday I noticed the problem. When accelerating to get on the highway I was WOT and when I got to the high RPM range (4-5.5) I noticed the engine....jolt, hesitate, stutter, skip, jerk while it was pulling.

This instantly bothered me so I called my cousins shop and told him what was happening. He suggested maybe it was bad gas, and to run this tank out fill up with premium and add a fuel cleaner. So fast forward a day or two and a lot of driving and I did what he said. I looked up top tier gas distributors and got premium at a local Exxon station. I also added Chevron Techron as recommended by many members here on the forums.

After doing that I am still noticing the problem. Further research on the forums was pointing me toward a fuel filter. The car has 44k miles on it and I didn't know if the previous owner ever changed it so I had a new one put on yesterday (Thursday). Took it out and the problem is still there. It may not be a big deal because under "normal" driving conditions you can’t really notice it. I am just super **** about my cars and I want them to run the best they can. Also just to note there are no CEL's we checked the airflow sensor, and when hooked up to the computer everything is reading correct as far as air flow and gas mixture. This leads me to think it may be electrical or spark. Thoughts? Very sorry about the super long post I just wanted to try and be as descriptive as possible.

CMcNam

I don't have enough experience to point to the specific solution, but some of the common problems that have been encountered are a dirty throttle body and problems with the charging system. An easy fix to a stalling problem I had was to remove the throttle body, spray it down with some throttle body cleaner, and wipe it clean. I'm not sure if this is related to your problem, but it can't hurt. Hopefully someone can chime in with a specific solution.

Sparta

Thanks for the response CMcNam. I forgot to mention we did do a visual inspection of the TB and it didn't appear to be very dirty so we didn't take it off to clean it. It may be worth a cleaning anyways.

ski

Also make sure all of the CAI connections are secure.

Nuke

The dirty TB tends to be notorious for idling issues, not WOT, but I'd clean it anyway. Even when they don't look bad visually, cleaning the TB has been known to resolve the idle issues.

As far as WOT, I'd certainly look at fuel delivery and replace the fuel filter as your first shot. Also, be sure the TCS is off. I've had issues with hesitation/no power at WOT on quite a few occassions that never happened again once I remembered to make it a habit to turn off TCS. TCS will cut spark and can really be embarassing at times.

ski

Just to make sure we're all on the same wavelength, the OP stated he changed the fuel filter on Thursday in his initial post, and it did not fix the problem.

jpplaw

Sounds ignition related to me. It is doing it at WOT, where she should be running pig rich. Replace the plugs and try it. Then, if the problem is still there, it may be a weak COP.
Hard to do a diagnosis without a code.

Nuke

Good call. Ignition wasn't even on my radar...

JFitz

COP could be it.

If you got bad fuel, then you need to change your fuel filter to really be sure. Easy to do and god those things get nasty.

Throttle body is also really easy to clean properly. Four bolts and TB cleaner and a tooth brush. Just don't mess with the throttle position sensor. It can screw things up if you knock that thing around.



Annnnnnnd check your clamps on that CAI. Could be running fine but when you push it, a leak present itself, too much air, runs leans...maybe?

Sparta

Thanks for the suggestions, I will try cleaning the TB tomorrow. Also what is COP?