prlj91

I've had my GT a little over a month, and I love the car. It performs well, and it's much more fun than my previous 3.9! I've got couple problems though, the main one being my bouncy idle.

The car, while in park, idles fine for the first 30 seconds or so, but after that, the RPMs bounce anywhere from about 200 to 700, then sometimes up to 1000, and the engine makes a surging sound. As soon as I come to a complete stop, it sits at a steady idle for a bit, then begins to surge a little. Also, pressing the brakes in even further when I'm stopped causes the idle to dip. It came with a K&N PFIK CAI on it, and I've never had a car with one before. To me, it sounds funny, but I'm not sure. It makes a sputtering sound occasionally, and I wonder if it's not installed correctly? Maybe there's and issue with it affecting the idle? I've already cleaned the MAF and IAC just to make sure those weren't malfunctioning, but it hasn't helped.

I've had my GT a little over a month, and I love the car. It performs well, and it's much more fun than my previous 3.9! I've got couple problems though, the main one being my bouncy idle.

The car, while in park, idles fine for the first 30 seconds or so, but after that, the RPMs bounce anywhere from about 200 to 700, then sometimes up to 1000, and the engine makes a surging sound. As soon as I come to a complete stop, it sits at a steady idle for a bit, then begins to surge a little. Also, pressing the brakes in even further when I'm stopped causes the idle to dip. It came with a K&N PFIK CAI on it, and I've never had a car with one before. To me, it sounds funny, but I'm not sure. It makes a sputtering sound occasionally, and I wonder if it's not installed correctly? Maybe there's and issue with it affecting the idle? I've already cleaned the MAF and IAC just to make sure those weren't malfunctioning, but it hasn't helped.

Thanks in advance for any suggestions!

GT210

Hmmmm you throwing any codes? Also have you checked for vacuum leaks dry rot hoses or anything like that. Maybe a bad gasket on the TB or egr or something just throwing thoughts out there.

96t-bird

+1 on the checking for a vacuum leak. old possibly dry rotted hose's,also bad gasket's. you visually check the hose's and also you can use a spray can to check for leaks.

prlj91

Yeah, I've tried checking the lines last night to no avail...should have updated the post. I haven't tried the spray can method, but I'll do that after work today. I guess just get brake cleaner and see if the idle surges? It's not throwing a code unfortunately. (fortunately?)

GT210

I ve never used brake cleaner I suppose that would work. What I use is throttle body cleaner. Also just cause you cant see a leak doesn't meant its not there. Another thing you can do as well is take a piece of hose if you have some laying around and put one end up to your ear and the other end stick it on the parts of the motor by the vacuum lines intakes, gaskets this will help you find it as well if you have a leak.

GT210

Do you have some sort of data logging tool that would help as well if you do.

Cockygt500

O2 sensor bad would be my guess. Pull it out and spray some carb cleaner on it and hit the tip with a old tooth brush. Put it back in and see if it still does it. Could also be a mapping sensor but sounds more like a dirty or bad 02 sensor. It doesn't always throw a code from my past experience. Good luck with the issue.

GT210

Ya could be a o2 as well like mentioned above. Try cleaning the front 2 o2 sensors and see what that does or if you some laying around just swap them out.

Fryguy22

clean your IAC valve with some throttle body cleaner.

BMWiduch

check your throttle body, or even your throttle position sensor might be going bad dude. Happens from time to time.