My 2006 G35 Coupe 6MT has developed an issue where as if I depress the clutch pedal at highway speeds (still in gear), the engine stalls. It only does this under these specific conditions. It idles fine at standstill/low speed coasting, is not low on power, no CEL, but the faster the car travels, and I press the clutch pedal, it idles erratically or dies, depending on speed. Cannot repeat this issue if I coast in neutral.

I've considered a few possible issues including a bad clutch pedal switch (doubtful), crank sensor (I'd expect a CEL, but I've seen stranger), or perhaps the bumper-mount CAI is leaning out the air/fuel ratio when coasting at that speed. The car has not been tuned, as I need a few more things done to it first, so I have a feeling this could be the issue, but surely someone else would have had this issue before too if this was the case...

 

Hi, my 03 G35 has been doing this for a while now and i can't figure it out. I've changed sensors, cleaned the MAF and throttle body with no success. I've come across other online forums where other cars have this issue and everyone says its their IAC valve. (idle air control)
I'm not sure but from my research I don't think my engine necessarily has one to change without replacing the entire throttle body. Please correct me if I'm wrong.
If you manage to see this, even tho this is a 3 year old post, and may have solved your original issue i'd appreciate the help! thank you

 

Had very similar issues...

I believe my idle issues were due to tuning/throttle body. Raising the idle fixed the stalling issue for me after pushing the clutch in. I do use a 75mm TB, so that may have been the reason/contributed.

 

Definitely was a thought back of my mind. I live in an area where we don't have much tuners. I got full bolt ons, still NA, but no tune. Definitely need one.