When I completely let off the accelerator, after 1-2 seconds the car will bog down (for lack of a better term) for a split second. Almost like I tapped the breaks. Just enough to make your head bob forward a bit. Letting off the accelerator at 3-4k RPMs in 2nd or 3rd seems to be the most noticeable.

And just to clarify. I'm not talking about engine braking. And this isn't under hard acceleration. Best scenario would be when I'm driving in heavy traffic, and I'm rolling along in 3rd at a constant speed and let off the accelerator to slow down (no braking involved).

Anyone else having the same issue?

 

Maybe a timing / valve timing thing? I wonder if at a certain rpm under trailing throttle, the valve timing might change which alters compression (and thereby increases engine braking)?

BTW, my immediate response to the title of your thread was "well, obviously you shouldn't let off the accelerator!"

EDIT:>>> Maybe I didn't understand your comment - you said it's not engine braking, correct? So the problem is that the engine braking isn't linear, you let off the gas, engine braking occurs, then you get a hitch where the car suddenly slows down more?

If it's just that you let off the gas, there's a second or two delay, then engine braking occurs, that probaby is a throttle map / drive-by-wire thing.

 

Happens to mine too.. I think its normal... I feel it the most in stop and go traffic.

Its not as smooth feeling but i can live with it considering the tranny shifts pretty firm.

 

i think it's something to do with the drive-by-wire system and emissions.

 

I think you are talking about the RPM dropping down and picking back up. It's some throttle map response.
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2008 g35 journey ivory/stone+prem&sport pkg.

 

That was my first thought, but my 05 didn't do it.

I've never seen the RPMs drop then come back up. There isn't even a big initial drop. They just start dropping slowly like you would expect when not giving it any gas.

 

Mine does the same thing. I try to be as smooth as possible taking my foot off the gas which helps but doesn't eliminate it. I noticed this on the stick that I drove at the dealership but didn't notice it on the auto.

 

nature of the flywheel and the gear ratio in 1st and 2nd?

 

You are most likely referring to driveline slack. Its a globally known characteristic of manual transmissions. In the lower gears, 1st 2nd and 3rd, it is the most noticeable. As soon as you let off the gas, you discontinue applying throttle, the motor stops sending input to the transmission, the driveshaft loosens up and you receive a small tug in return. As soon as you re-apply throttle, you restart the flow of input to the transmission and the driveshaft tightens back up . Ive felt this in every single car Ive driven with a manual transmission. This is the least noticeable in FWD cars, especially Honda's, considering they have one of the smoothest MT's in the industry.

 

ya its normal mine does it when you let of the gas

 

I'd say a combination of rev matching and engine braking (really due to exhaust backpressure).

It seems less apparent after I had a new exhaust installed. Now my car downshifts bringing the revs up high without the "braking" feeling. I think you can hear it on a couple of video clips in post 72 here:

https://g35driver.com/forums/showthr...=195719&page=5

In any case ... totally normal.

 

It has nothing to do with the drive train slack.
It has to do with the ECU and electronic throttle.
when u take ur foot off the gas, the ecu throttles back the engine, but it doesn't completely close the throttle body, it does that about 1 second after your foot has been off the gas.

In this car you do not control the throttle, the ecu does. When u push on the throttle you tell the ecu to rev up the engine. The ECU determines how and when to open the throttle body’s, and also when to close them.
That’s how they can fix the throttle response with an ecu update.
In older cars, that don't have electronic throttles, the throttle body is connected to the pedal with a cable. In the older style the ecu would control timing and the fuel/air ratio based on the throttle body position.

you can feel this same effect if your cursing at about 40mph and have ur foot slightly on the gas, then quickly push it to about 3/4 throttle. ull feel the car hesitate for just a split second, then accelerate. That’s the ecu, not ur foot.
Try this a few times and ull feel the hesitation. It’s very small but if u do it a few times u can feel it on the 6mt 07+.

Ask technosquare, He knows all about this.

 

well everyone that says theirs does it do you have a 6mt ? I have an auto and i notice the bog as well.

 

The same thing happened to me. It was a snow storm this morning with stop and go traffic. I only got 1200 KM on my 08 G35xS and I think this is kind of normal.

 

yeah, i kinda find it bothersome, when you totally let off the gas it feels like it downshifted into a lower gear,
the only way to combat this is having a steady foot and drive like a grandma, if you let off the accelerator slowly and smoothly it doesn't jerk...
or the other way is to buy an aftermarket exhaust as mentioned above...