I'm getting problem after problem and it's driving me a bit nuts. I had some rough idle so I did the throttle body cleaning as instructed in the DIY thread. I did end up touching my valves a little and I'm hoping this isn't what is causing all of my problems.

Before the cleaning, my car would idle at 650 RPMs and the RPM needle on the tach wouldn't move but my car would seemingly cough and shake randomly. Now it idles anywhere from 750 to 900 RPMs and is constantly moving up or down and changes while I'm driving. However, the coughs/shakes aren't nearly as bad as before when sitting in idle.

The weird part is when I accelerate then press in the clutch pedal and/or shift to neutral, the RPM drops to around 1,300 and sits there for a few seconds then drops back down. If I'm driving under 1,300 RPMs and go to neutral, the RPMs will drop to like 500 and pop back up to 1,300 then settle back to ~800. The weirdest thing of all is that if I'm moving in 2nd gear, I can take my feet off of all pedals and the car will settle in at 1,100 RPMs and keep going without stalling. If I'm in second and at like 900 RPMs and let go of all pedals, it will accelerate up to 1,100 and stay there... wtf?!

I think a trip to the mechanic is in order but just wanted to get some ideas of what could be wrong. Knowledge = power! Oh and I did all of the relarnings including the accelerator pedal release, throttle valve close position, and idle air volume. I also reset my ecu over night and still the same. The idle air volume relearning helped drop the idle RPM from 1,100 to 800-900 but now I have all of the problems mentioned above.

 

I was about to do the DIY throttle body cleaning too. I'm getting the rough idle also when i stop the RPMs range will drop to about 500 and feel like its about to die sometimes. i have 42k miles any lessons learned would be helpful.

 

It isn't hard to clean the throttle bodies and it sounds like cleaning it would solve your problem.

My advice is work very carefully. Make sure all of the parts are in place as you removed them and don't unclip/remove any wiring or harnesses (I only took out my intake tubes but left all other clips/wires/harnesses on). I would recommend NOT moving the valves at all so just wipe around the inside and use q-tips to get around the valve edges with the throttle body cleaner. Best of luck!

 

Have you done these?
1 -ACCELERATOR PEDAL RELEASED POSITION LEARNING
2 -THROTTLE VALVE CLOSED POSITION LEARNING

Post number 78 in this thread explains how: https://www.myg37.com/forums/d-i-y-i...-bodies-6.html

(i read through all 11 pages before cleaning my TB's)
When i followed the DIY to clean the TB's i moved the butterfly carefully to clean the edges, after putting everything back together the idle seemed higher than usually so i had to do some more searching through the forum to find how to do #1 and #2 above. This solved my problem and the care has idled great since then. If you decide to do #1&2 make sure your care is warmed up to operating temperature.

 

Yup did the whole procedure... several times actually. Did it once, drove it for a couple of days and then reset the ECU via removing the negative line from the batter and did it again. It has been the same.

 

I know this is a very late response on my part, but if you're still active on here, did you ever figure out what was causing this? I cleaned my throttle bodies a while ago now, and ever since then when I come to a stop at a light my RPMs drop to 500. It idles at maybe 600 or less in Park which is still too low. Oddly enough it only idles at 500 for about 20 mins of driving, then it goes back up to my now normal Park idle. What did you do to remedy this, if you have? I have a 2012 G37x Sedan

 

Did you initiate the idle air volume learning?

Here's an excellent how-to:

 

Yes, I've done that and it only "fixes" the issue until I start driving again. Then it reverts back to how it was. When I tap on the black side piece of the driver side throttle body, I can hear a spring inside making noise. Not sure if that indicates an issue, but the other throttle body doesnt make a sound. You or anyone else have advice considering all that?

 

Check for vacuum leaks?

 

The suspect the spring sound is normal.

Here is a video on the inside of a G37 throttle body: