Orbie

Ok I've been having this issue with my G37 (5AT) for a few months now. I keep thinking it's an oddity and will go away but it so far seems to keep reoccuring.

So what I'm seeing is that sometimes when I'm driving the car for a while (1 hour +) usually in warmer weather, all of a sudden when I come to a stop the engine will all of a sudden drone really loud. When you look at the tach the rpm's seem to be idling quite high, at around 1K (usually idle is 700 or so). It's like the engine is having an issue determining the proper idle speed when the car is stopped, and it's thinking it needs to idle higher. When you start accelerating again, the car will lurch forward right away and then accelerate with almost no power (no matter how hard you step on the gas). It's almost like a brake torque at 1000rpm at the beginning then the engine flips and there's no power. As the rpm's rise and the car upshifts, the car will start to drive like normal. But when you slow down to a stop again the car will again idle at the 1000 rpm range. It doesn't matter if you put the car in DS or manual mode, the car behaves the same.

The one thing that I've found solves the problem everytime (so far) is turning the car off and turning it back on. So usually when I hit a light I'll turn the car off and on. The car will then start and idle normally (at ~700rpm). From that point on the car seems to behave as normal. I haven't driven long enough for it to happen again, so so far it seems it only happens once when it does occur. Very annoying and freaky though as I'm not sure if something more major is going to break down the line. I haven't determined if there's a pattern on when this happens yet, but it seems to just be on long trips, city driving in warmer weather.

I'm thinking something is wrong with the VVEL timing on idle or maybe the MAF? anyone had this happen to them before? I think there were some TSB's on VVEL timing re-flashes a while ago, but from what I remember people who did them started to have other issues...

bboysteele

My guess is you have an AT and not a MT since you don't have a sig that tells us or posted what you have. It sounds like the TSB that was released for the AT cars with ruff idle and quick jerky acceleration after stopping. Take it to the dealer. Just because you "heard" some people have had issues after getting the reflash should not stop you. To be honest I don't remember reading one post or thread about someone having an issue after this. Get it fixed. You don't want to accidentally rear-end someone because it happens at a point that you are not paying close attention.

shumby

iTrader: (3)

He says 5at right in his first line.

Orbie

Thanks for the input, as Shumby mentioned, I have a 5AT, it says right in the first line of my post. I also mention that I have this problem if I put the car in DS or manual mode which is 5AT only.

I actually read a lot of posts about the rough idle and acceleration when braking, but I don't believe that is the problem here. The rough idle could be applicable but it seems the main distinguishing trait is the acceleration while braking. There definitely isn't any of that. I can brake like normal with no problems, even when I let my foot off the brake from a stop the car doesn't just jerk forward, it only does this when I hit the accelerator. It just seems like when downshifting to 1 and stopping the car idles high, which explains the jerky acceleration when I hit the gas, it's just strange that I seem to lose power right afterwards.

Oh well, I'll just call up the stealership.

bboysteele

LOL, why the heck did I not see that last night. Man, no more late night thread reading for me. When you take it to the dealership, let us know if it is more than the ECU reflash.

G37SUM!

orbie!! same issue see my post here

https://www.myg37.com/forums/engine-drivetrain-and-forced-induction/180822-idle-rpm-high-and-ses-light-on.html

This description is exactly like mine

So what I'm seeing is that sometimes when I'm driving the car for a while (1 hour +) usually in warmer weather, all of a sudden when I come to a stop the engine will all of a sudden drone really loud. When you look at the tach the rpm's seem to be idling quite high, at around 1K (usually idle is 700 or so). It's like the engine is having an issue determining the proper idle speed when the car is stopped, and it's thinking it needs to idle higher. When you start accelerating again, the car will lurch forward right away and then accelerate with almost no power (no matter how hard you step on the gas). It's almost like a brake torque at 1000rpm at the beginning then the engine flips and there's no power. As the rpm's rise and the car upshifts, the car will start to drive like normal. But when you slow down to a stop again the car will again idle at the 1000 rpm range. It doesn't matter if you put the car in DS or manual mode, the car behaves the same.