Single knock when coming to a stop - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

oops86 · 07-29-2012, 03:51 PM

I have an Automatic FR-S with about 1250 miles on the odometer. When I come to a complete stop, I hear a single, quiet knock from the engine compartment. Sometimes it's slightly louder than at other times and you have to listen closely to hear it, but it is there. It happens on average around three out of ever five stops. I'm paranoid as to whether or not this might be engine knock. Does anyone have any ideas as to what might be causing this and should I get it checked out?

Dadhawk · 07-29-2012, 04:28 PM

Quote:

Originally Posted by oops86

I have an Automatic FR-S with about 1250 miles on the odometer. When I come to a complete stop, I hear a single, quiet knock from the engine compartment. Sometimes it's slightly louder than at other times and you have to listen closely to hear it, but it is there. It happens on average around three out of ever five stops. I'm paranoid as to whether or not this might be engine knock. Does anyone have any ideas as to what might be causing this and should I get it checked out?

All I can add is that I have not ever noticed this particular sound. If you're concerned its worth getting it checked out.

mediumbrown · 07-30-2012, 02:42 AM

i too have an automatic and i hear this audible "click", BUT mine can be felt (very slightly) from the gear lever selector and to me it sounds like thats where it comes from...

consistently it happens from when slowing down to a complete or near complete stop...

Bonburner · 07-30-2012, 02:54 AM

Any chance for an audio clip?
I don't think my M/T has this. :x

Pscylo · 07-30-2012, 06:41 AM

Does it happen every few seconds when you hear it, and you only hear it while stopped?

oops86 · 07-30-2012, 07:32 AM

Quote:

Originally Posted by mediumbrown

i too have an automatic and i hear this audible "click", BUT mine can be felt (very slightly) from the gear lever selector and to me it sounds like thats where it comes from...

consistently it happens from when slowing down to a complete or near complete stop...

When you mean gear selector, do you mean the shifter? If so, next time I drive it, I'll have to put my hands on it to feel it.

Quote:

Originally Posted by Pscylo

Does it happen every few seconds when you hear it, and you only hear it while stopped?

It's a single "knock" sound. I only hear it once.

eriktherod · 07-30-2012, 08:39 AM

I'm assuming it's the transmission going back into first. If I do similar on my MT and then go into first somewhat soon after stopping (from neutral), I'll feel a similar 'thud' from the transmission. It almost feels like it pulls me forward slightly but it's just the input shaft being stopped quickly and is normal noise.

Does yours happen EVERY single time you stop? Mine only occurs sometimes.

Dadhawk · 07-30-2012, 10:54 AM

Quote:

Originally Posted by oops86

When you mean gear selector, do you mean the shifter? If so, next time I drive it, I'll have to put my hands on it to feel it.

It's a single "knock" sound. I only hear it once.

Quote:

Originally Posted by eriktherod

I'm assuming it's the transmission going back into first. ....

I suppose it could be the torque converter unlocking, but still haven't noticed it.

mediumbrown · 07-30-2012, 01:57 PM

Quote:

Originally Posted by oops86

When you mean gear selector, do you mean the shifter? If so, next time I drive it, I'll have to put my hands on it to feel it.

yes the "PRNDL" lol

i thinks its the normal sound that our auto transmission, it may just be more noticeable because the transmission is so close to the cabin vs other FWD auto trans for example

so its either our auto trans have issues or its nothing to worry about..

other A/T drivers... does yours do the same thing?

oops86 · 07-31-2012, 10:10 PM

I've scheduled an appointment for a ride on later this week. They're also going to check to see if there's any records of knock recorded in the ECU. I'm thinking you guys might be right and that it's just the transmission shifting out of first, but I'm taking it in to double check. After all, it never hurts to check. I'll let you guys know what I hear.

mediumbrown · 08-01-2012, 01:11 AM

Quote:

Originally Posted by oops86

I've scheduled an appointment for a ride on later this week. They're also going to check to see if there's any records of knock recorded in the ECU. I'm thinking you guys might be right and that it's just the transmission shifting out of first, but I'm taking it in to double check. After all, it never hurts to check. I'll let you guys know what I hear.

keep us updated, i'm almost certain it is NORMAL, but yeah it never hurts to get it verified...

were you able to hear/feel it through the shift lever?

oops86 · 08-04-2012, 05:34 AM

Quote:

Originally Posted by mediumbrown

keep us updated, i'm almost certain it is NORMAL, but yeah it never hurts to get it verified...

were you able to hear/feel it through the shift lever?

So I took it in and did a ride along yesterday. Yes, the shift lever was the source of the sound and the mechanic that rode along with me said the reason I hear it is because they designed a little extra play in the transmission because the engine could be torquey. I told him I could have sworn up and down that I heard a knock behind the firewall the last time I drove it and he said that's a distinct possibility, but the causes would be the same. He said to just keep an ear out for if and when it ever starts to sound unhealthy and if and when it does, bring it on in.

DaJo · 08-04-2012, 05:43 AM

Quote:

Originally Posted by oops86

So I took it in and did a ride along yesterday. Yes, the shift lever was the source of the sound and the mechanic that rode along with me said the reason I hear it is because they designed a little extra play in the transmission because the engine could be torquey. I told him I could have sworn up and down that I heard a knock behind the firewall the last time I drove it and he said that's a distinct possibility, but the causes would be the same. He said to just keep an ear out for if and when it ever starts to sound unhealthy and if and when it does, bring it on in.

So glad this mechanic actually took the time to go through everything and explain in detail with you...Instead of just saying "It's normal"

Roadstercycle · 08-04-2012, 07:40 AM

Hi, its a little electronic pendalum in the shifter mechanism. I believe its a reverse lock out. You can take the shift boot off and watch it work. Drove me crazy, could not see anything while parked.. So I decided to drive it with the boot off. Low and behold I watched extend and retract. Swings up as you start moving and swings down and thuds. Needs a piece of felt or foam.

07-29-2012, 03:51 PM	#1
oops86 Member Join Date: Jun 2012 Drives: Scion FR-S Location: Ohio Posts: 65 Thanks: 45 Thanked 17 Times in 11 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Single knock when coming to a stop I have an Automatic FR-S with about 1250 miles on the odometer. When I come to a complete stop, I hear a single, quiet knock from the engine compartment. Sometimes it's slightly louder than at other times and you have to listen closely to hear it, but it is there. It happens on average around three out of ever five stops. I'm paranoid as to whether or not this might be engine knock. Does anyone have any ideas as to what might be causing this and should I get it checked out?

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07-30-2012, 02:42 AM	#3
mediumbrown Member Join Date: Jul 2012 Drives: 2013 Argento Scion FR-S Location: USA Posts: 74 Thanks: 15 Thanked 28 Times in 14 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	i too have an automatic and i hear this audible "click", BUT mine can be felt (very slightly) from the gear lever selector and to me it sounds like thats where it comes from... consistently it happens from when slowing down to a complete or near complete stop...

07-31-2012, 10:10 PM	#10
oops86 Member Join Date: Jun 2012 Drives: Scion FR-S Location: Ohio Posts: 65 Thanks: 45 Thanked 17 Times in 11 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	I've scheduled an appointment for a ride on later this week. They're also going to check to see if there's any records of knock recorded in the ECU. I'm thinking you guys might be right and that it's just the transmission shifting out of first, but I'm taking it in to double check. After all, it never hurts to check. I'll let you guys know what I hear.

08-04-2012, 07:40 AM	#14
Roadstercycle FRS Rear Mount Turbo Join Date: May 2012 Drives: 2013 FR-S Raven, Rear Turbo Location: Torrance, Ca Posts: 193 Thanks: 53 Thanked 113 Times in 49 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Hi, its a little electronic pendalum in the shifter mechanism. I believe its a reverse lock out. You can take the shift boot off and watch it work. Drove me crazy, could not see anything while parked.. So I decided to drive it with the boot off. Low and behold I watched extend and retract. Swings up as you start moving and swings down and thuds. Needs a piece of felt or foam.

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