Hey guys, sorry if this is a repost, but I used the search function and couldn't find anything.

I drive a '10 G37 Sedan Journey with 38,xxx miles on it. I frequently drive it in DS mode, shifting for myself. The car had been not rev matching downshifts every now and then, and now it almost never does. It used to be that I could restart the car twice (it was ALWAYS twice) and it would work again, no issues.
The problem started a couple weeks ago, and now it's really starting to worry me.

Has anyone else had this problem? Or does anyone know what may be causing it?

And yes I know, should have bought 6/MT, blahblahblah…

Thanks for any help y'all can offer.

- Bailey

 

i thought that only the S or XS had the rev matching... i could be wrong

 

Nope, all G's definitely have rev matching.

 

What does it do instead of rev matching?

 

LOL, and yes, my older 6MT rev matches on all down shifts ...

 

It would simply just shift without rev matching. I cleaned the TB's and air filters, and it started working again… I think maybe the MAF was getting weird readings and telling the computer weird stuff, it pulls harder now too. Weird. Just really weird.

 

G owners should clean MAF's every single year.

MAF sensors can become very dirty over time, and it will suck the life blood out of your engine. Search around this forum for people with MAF issues, it is notorious for fooling your engine, your transmission, and even other sensors.

A dirty MAF is like having a nose full of boogers....breathing is definitely not proper.

 

How are you cleaning them. Just MAF cleaner for the auto parts store? I have never cleaned these before? And this weekend I'm thinking of doing the TB's, and changing the plugs, on my car.

 

or

 

+1 on MAF. I cleaned my air filters and that helped it. I think you're definitely right though. Will be hitting up auto zone tomorrow and then searching for the DIY.

Thank you!

 

What does it feel when there's no rev match on an automatic? A couple other automatic cars that I am sure have no rev match do not drive much different than the G37. Rev match is only useful on a manual car IMO.

 

If you're just in D, and mostly in DS, you won't really feel the rev-matching. In D (assuming you don't have the latest transmission TSB, version D I think), you will only feel the rev-matching under extremely hard braking. Essentially, the car will use engine braking to assist in an emergency stop. In DS, the threshold for setting off the engine braking is lower, so on tight turns when braking on entry, the car will drop 1-2 (sometimes 3) gears, rev-matching with each one.

The sensation that you get when this happens is essentially an increase in acceleration, then a sudden decrease. So, to give an example, imagine you're standing on the brakes. In a normal car, the engine doesn't assist with any braking, so the feel is very linear. Your body get thrown forward and stays there as you slow down. In the G, it's not linear. Initially, your body will get thrown forward, then as the transmission calls upon the engine to assist with braking, the transmission releases the current gear, causing you to have the sensation of "falling" back into your seat. The engine will rev-match and the transmission will engage the lower gear, causing you once again to be flung forward with more energy. This time you move forward the G forces are even stronger than the initial bite, since the car is using the kinetic energy of the engine to assist in slowing down.

In reality, you may or may not feel this way when braking. Ideally, you shouldn't feel a perception of changing accelerations, but since the G doesn't have a dual clutch transmission, and has to release the higher gear before rev-matching, many times this delay is noticed by what I described above.

 

Actually the rev-matching is very useful in manual mode, still useful in DS and D under heavy braking bit in manual mode it really shines.

 

LOL at this comment Chili!

 

Same problem is happening with me right now. It rev matched sometimes, but sometimes it doesnt. Did you ever figure out the issue?