Tranny Rattle ???

[ArtS]

Has there been any agreement among FRS/BRZ owners as to the cause of the well reported "transmission rattle" when slowing down in neutral? I've seen all kinds of theories suggested here - engine valve noise, fuel pump noise, exhaust noise, piston slap, etc. I think its in the transmission/clutch because when the clutch is pushed in the noise stops immediately. It only happens for about 2-3 seconds at about 700 rpm, clutch out in neutral. What is the best educated guess to what makes the noise???


ArtS - 2015 FR/S manual tranny

[steve99]

Originally Posted by ArtS

Has there been any agreement among FRS/BRZ owners as to the cause of the well reported "transmission rattle" when slowing down in neutral? I've seen all kinds of theories suggested here - engine valve noise, fuel pump noise, exhaust noise, piston slap, etc. I think its in the transmission/clutch because when the clutch is pushed in the noise stops immediately. It only happens for about 2-3 seconds at about 700 rpm, clutch out in neutral. What is the best educated guess to what makes the noise???


ArtS - 2015 FR/S manual tranny

When you coasting to stop (zero throttle) the ecu shuts off fuel injectors ( fuel saving) and the momentum of car keeps engine turning, at some point arround idle rpm the ecu will turn on fuel injectors to keep engine rpm arround idle rpm. The noise is just backlash in drivetrain as this occurrs, especially in combination with airconditioner switching.

You can alleviate the issue with tuning to bump idle to 750 and switch to full direct injection mode at low loads, instead of combination pi\di, this allows ecu to manage idle stability better.

[ArtS]

Steve99 - Thanks for the reply but I don't think I agree. When the condition I describe occurs I am in neutral coasting to a stop. The cars momentum is not turning the engine. Only when I am almost stopped and the RPM is down to 650 -750 do I hear clearly the noise from the clutch/tranny area. Your 2nd sentence about "bumping the idle and switching to full di", wow, I'm not in that league. Thanks anyhow.
Art

[steve99]

'

Originally Posted by ArtS

Steve99 - Thanks for the reply but I don't think I agree. When the condition I describe occurs I am in neutral coasting to a stop. The cars momentum is not turning the engine. Only when I am almost stopped and the RPM is down to 650 -750 do I hear clearly the noise from the clutch/tranny area. Your 2nd sentence about "bumping the idle and switching to full di", wow, I'm not in that league. Thanks anyhow.
Art

Their is still some idle stability issues even in 2015 cars, even with clutch disengaged or in neutral the engine almost stalls the ecu catches it and you get that rattly sound, the a\c switching can make it more noticable. it pretty well documented. its not causing any issue just annoying.

search for idle stability issues

[ArtS]

Steve99 - Thanks for the second reply. I think I like this answer a little more than the first one. By the way, isn't the internet amazing? I sit here in South Carolina, ask a question on my computer and in a couple of minutes I get a reply from Australia. God, what a world we live in!
Art

[steve99]

Originally Posted by ArtS

Steve99 - Thanks for the second reply. I think I like this answer a little more than the first one. By the way, isn't the internet amazing? I sit here in South Carolina, ask a question on my computer and in a couple of minutes I get a reply from Australia. God, what a world we live in!
Art

If you can check your ECU software revision for a manual it should be

ZA1JB01C
or if latest model car
ZA1JD00C

You can do that with android torque application and cheap elm327 adapter

if it not one of those dealer should update you to latest one for your car.

If you had a flash device I could send you a new tune :-)

[jbailey8748]

There is a tsb for rattling shifter, it has to do with bushings and they replace the whole shifter. Maybe this will help

Sent from my SAMSUNG-SM-G900A using Tapatalk

[humfrz]

Originally Posted by ArtS

Steve99 - Thanks for the second reply. I think I like this answer a little more than the first one. By the way, isn't the internet amazing? I sit here in South Carolina, ask a question on my computer and in a couple of minutes I get a reply from Australia. God, what a world we live in!
Art

DANG, ArtS ....... when did ya'll get Internet access down in Bluffton .....??

(jest ah messen wich ya ..... )


humfrz

[ArtS]

humfrz -


No matter what you say the internet is one of the most significant developments of the last century. I am old enough to have been around before you were born, the internet was created, before cell phones and even before tv! Its all a matter of historical perspective. So, I know you were just kidding around, but I'll stick with my comments and say "wow, what a world!"


ArtS