Knocking sound - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Moe23 · 01-20-2014, 02:38 PM

This morning I started my FR-S, as the car was at cold start everything was fine, once the RPM dropped to idle there was a noticeable knocking sound from the engine while the car was still cold. Once the car had fully warmed up the knocking goes away.
Anyone else ever had that problem?

stugray · 01-20-2014, 02:43 PM

In cars with hypereutectic pistons (which this probably has - not sure), you will have noticeable "piston slap" until it warms up.

I have not noticed it. Did you have to get out of the car to hear it?

tobin · 01-20-2014, 02:52 PM

My BRZ does the exact same thing, and it goes away when it's warmed up. I'm glad I'm not alone!

Moe23 · 01-20-2014, 04:10 PM

No i can hear the noise from the inside of the car not the outside

Mikem53 · 01-20-2014, 06:53 PM

Quote:

Originally Posted by Moe23

This morning I started my FR-S, as the car was at cold start everything was fine, once the RPM dropped to idle there was a noticeable knocking sound from the engine while the car was still cold. Once the car had fully warmed up the had knocking went away.
Anyone else ever had that problem?

I get it too.. Some say it's caused by the cat heating up. The engines knocks
and it feels like a backfire. Only a few stumbles and it smooths out. It's not piston slap..

Moe23 · 01-20-2014, 11:53 PM

Quote:

Originally Posted by Mikem53

I get it too.. Some say it's caused by the cat heating up. The engines knocks
and it feels like a backfire. Only a few stumbles and it smooths out. It's not piston slap..

The knocking lasting for about 20 minutes, is that normal?

humfrz · 01-21-2014, 01:06 AM

Quote:

Originally Posted by Moe23

The knocking lasting for about 20 minutes, is that normal?

Well, my FR-S doesn't do that ..... but it doesn't get real cold here.

I'd be a bit concerned if the "knocking" went on for 20 minutes.

Can you capture a video/audio and post it .. ??

....and, of course you have checked the oil level....

Hakuzen · 01-21-2014, 01:53 AM

Quote:

Originally Posted by Moe23

The knocking lasting for about 20 minutes, is that normal?

My car sounds rough on a complete cold start.. Almost sounds like its knocking for the first few seconds after ignition, but it never lasts more than a few seconds.

If that knocking noise persists for 20 minutes, I'd be concerned.

Mikem53 · 01-21-2014, 08:00 AM

Quote:

Originally Posted by Moe23

The knocking lasting for about 20 minutes, is that normal?

No..

Muskokan · 01-21-2014, 08:28 AM

Quote:

Originally Posted by Moe23

The knocking lasting for about 20 minutes, is that normal?

Was this thismorning? It's -40 with the wind chill up here so if your parked outside, my engine took over 20 m of driving to even move the temp quage.

My radio still hasn't turned on either

Hopefully my balls reappear soon

Edit: I see it was yesterday morning, still pretty cold. Go out thismorning and take a vid of start up and post it here.. Dress warm

Moe23 · 01-21-2014, 12:20 PM

Quote:

Originally Posted by humfrz

Well, my FR-S doesn't do that ..... but it doesn't get real cold here.

I'd be a bit concerned if the "knocking" went on for 20 minutes.

Can you capture a video/audio and post it .. ??

....and, of course you have checked the oil level....

I will try to get a video of it knocking, and i got an oil change two days before it starting knocking, and oil level is fine

BlackyRose · 01-21-2014, 02:19 PM

I live in Florida, and on cold starts I get 2-3 loud knocks withing the first 30 seconds and then everything is fine once I put her in reverse. The knocks are so bad that the car almost shakes a little bit.

No codes, no drop in performance, etc. Seems to be normal on our cars when they get cold

Moe23 · 01-21-2014, 07:20 PM

Quote:

Originally Posted by BlackyRose

I live in Florida, and on cold starts I get 2-3 loud knocks withing the first 30 seconds and then everything is fine once I put her in reverse. The knocks are so bad that the car almost shakes a little bit.

No codes, no drop in performance, etc. Seems to be normal on our cars when they get cold

It doesn't knock during cold start, but right after the RPM drops to normal idle, and the knocking is constant for about 20 minutes, and the car does shake a bit with every knock

humfrz · 01-21-2014, 07:41 PM

Quote:

Originally Posted by Moe23

It doesn't knock during cold start, but right after the RPM drops to normal idle, and the knocking is constant for about 20 minutes, and the car does shake a bit with every knock

Well, if I had to guess, I'd guess your car has a coil/plug or the wire leading up to one of them acting up.....

01-20-2014, 02:38 PM	#1
Moe23 Member Join Date: Jan 2014 Drives: 2014 Scion FRS MT Location: Mississauga, Ont Posts: 61 Thanks: 20 Thanked 18 Times in 11 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Knocking sound This morning I started my FR-S, as the car was at cold start everything was fine, once the RPM dropped to idle there was a noticeable knocking sound from the engine while the car was still cold. Once the car had fully warmed up the knocking goes away. Anyone else ever had that problem? Last edited by Moe23; 01-21-2014 at 10:55 PM.

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01-20-2014, 02:43 PM	#2
stugray Banned Join Date: Sep 2013 Drives: 2013 GBS BRZ Limited Location: Colorado Posts: 1,925 Thanks: 627 Thanked 1,445 Times in 711 Posts Mentioned: 41 Post(s) Tagged: 0 Thread(s)	In cars with hypereutectic pistons (which this probably has - not sure), you will have noticeable "piston slap" until it warms up. I have not noticed it. Did you have to get out of the car to hear it?

01-20-2014, 02:52 PM	#3
tobin Senior Member Join Date: Jun 2013 Drives: '13 BRZ Location: CT Posts: 485 Thanks: 314 Thanked 330 Times in 155 Posts Mentioned: 6 Post(s) Tagged: 1 Thread(s)	My BRZ does the exact same thing, and it goes away when it's warmed up. I'm glad I'm not alone!

01-20-2014, 04:10 PM	#4
Moe23 Member Join Date: Jan 2014 Drives: 2014 Scion FRS MT Location: Mississauga, Ont Posts: 61 Thanks: 20 Thanked 18 Times in 11 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	No i can hear the noise from the inside of the car not the outside

01-21-2014, 02:19 PM	#12
BlackyRose Senior Member Join Date: Jun 2013 Drives: 2013 Raven FR-S Location: Florida Posts: 486 Thanks: 31 Thanked 59 Times in 44 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	I live in Florida, and on cold starts I get 2-3 loud knocks withing the first 30 seconds and then everything is fine once I put her in reverse. The knocks are so bad that the car almost shakes a little bit. No codes, no drop in performance, etc. Seems to be normal on our cars when they get cold

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