Starts to buck at around 3 or 4k RPMs
 

Hopefully someone can help me on this. I have a '11 Touring Sports Package Manual Transmission. 5k mileage. I have installed AEM ETI cold air intakes and a Stillen catback exhaust. It has ran perfect since I got it a couple months ago with these upgrades. The other day it started downpouring and the roads had standing water. I'm positive I got a couple of waves through my grill and splashed on my filters. It started bucking and I couldn't drive faster than 65 miles an hour.

Pulled over and waited till it stopped and started back home. The problem was the same all the way home. I let the car sit over night and half the next day. When I started driving it, it was all messed up, but as I continued it performed better and better and finally the best it's ever run as far as torque and response.

A few days later I noticed that if I slowly accelerated it started to "buck" when I reached 3 or 4k RPMs. Now, if I accelerated fast it didn't do it, only rarely. So, I filled up and ran through some Octane Boost through the fuel thinking maybe I have a moisture problem and also cleaned the MAF sensors. Nothing is working. I also reset the ECU by unplugging the battery and still no fix.

Could this possibly still be moisture in the cylinders or plugs? I wouldn't think so after a week but, I have no idea. Could the exhaust have anything to do with it? Anyway, sorry for the ramble but I wanted to give all the details. If someone has a suggestion, I'd love to hear it.

Thanks.

It sounds like wet or clogged filters.
I would remove the front bumper, take off the filters, clean, and allow them to completely dry.

When I cleaned the MAF sensors they were bone dry...as for clogged? Maybe. I guess I'll have to take it all apart again and at least try it...

if the filters are still damp or wet?

use a blowdryer to dry the filters out

The filters were bone dry. Is it possible that back flow from the exhaust can do that? Because when this happens I hear it in the exhaust too...I dunno. Just throwing it out there..

Update: Fixed!
 

So after changing the plugs, cleaning the MAFs and MAP, cleaning the filters, switching the MAFs, checking for vacuum leaks over and over and reassembling the exhaust and intakes twice, buying a programmer and tuning..I finally found the problem.

As I was rereading the AEM intake instructions, I noted that the ETI feature configured the signals to the ECU to be read as a stock intake/airbox due to the fact that the piping was much wider. I knew this but, didn't put two and two together...This is supposed to be the new technology for AEM (ETI) and allows more airflow through their intakes that can be read correctly by the ECU.

As I was thinking, I have an aftermarket exhaust and I also punched out holes in the grill for more airflow. The factory preset control modules in the wiring of the MAFs probably couldn't register the amount of airflow I was providing (as I'd proposed but have no idea). So, I cut out both modules and spliced the wires back together so it was just MAF to ECU. Then, I retuned for aftermarket intakes. Guess what? PURRS like a kitten and the throttle response is instant.

It only took me a month, a lot of cash and about a hundred hours of labor but, it was the fix. I hope if anybody else runs into this problem this will help.

Happy Driving!

Chip