Clanking sounds when revving from low rpm
#1
Clanking sounds when revving from low rpm
Hi guys
i am noticing a pretty loud clank when I hit the throttle from <1200 rpm
You can hear the sound at 10, 12 and 14 seconds in the below audio clip.
2007 997 4S
Any ideas?
https://www.dropbox.com/s/yfzqa2klk8...d%203.m4a?dl=0
i am noticing a pretty loud clank when I hit the throttle from <1200 rpm
You can hear the sound at 10, 12 and 14 seconds in the below audio clip.
2007 997 4S
Any ideas?
https://www.dropbox.com/s/yfzqa2klk8...d%203.m4a?dl=0
#2
Rennlist Member
I thought I also hear a slight similar sound at the 4 sec mark.
Almost sounds like the lag sound (valve tap) when you are in too low a gear and put stress on engine
Better qualified will give input I'm sure.
Almost sounds like the lag sound (valve tap) when you are in too low a gear and put stress on engine
Better qualified will give input I'm sure.
#3
Does she burn oil?
Edit: after you figure out what the problem is you might want to consider switching to 5W oil if you’re running 0W. But don’t start with that. Leave everything like it is until you get it diagnosed. Smarter people than me will chime in shortly.
Edit: after you figure out what the problem is you might want to consider switching to 5W oil if you’re running 0W. But don’t start with that. Leave everything like it is until you get it diagnosed. Smarter people than me will chime in shortly.
#4
Three Wheelin'
Do you live in California? If so its engine knock from the 91 octane, at least thats the best explanation I got.
I had a similar knock blipping the throttle below 2k rpm when I first got my car. I solved it by not blipping the throttle below 2k rpm anymore :-)
I had a similar knock blipping the throttle below 2k rpm when I first got my car. I solved it by not blipping the throttle below 2k rpm anymore :-)
#5
RL Community Team
Rennlist Member
Rennlist Member
Take a look at your motor and transmission mounts. Sounds like the initial torque of the motor when you hit the gas is causing it to contact something metallic, maybe a coolant pipe like those that fastened around the oil sump or something near an exhaust component.
#6
I thought I also hear a slight similar sound at the 4 sec mark.
Almost sounds like the lag sound (valve tap) when you are in too low a gear and put stress on engine
Better qualified will give input I'm sure.
Almost sounds like the lag sound (valve tap) when you are in too low a gear and put stress on engine
Better qualified will give input I'm sure.
Last edited by retlas; 09-09-2019 at 11:34 AM. Reason: added quote
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#8
Hmm, the local station only has 91 - but the Shell station has 93. It's a good idea and I will fill up the next time with 93 and see if it makes a difference - thank you.
#9
Hi, I had thought something similar and just replaced the engine mounts as I had inspected and found about a 8mm drop on the right side of the engine. The new mount leveled things back up but didn't stop the noise.
#10
Three Wheelin'
Keep me posted if the 93 helps. That would put the mystery to bed, as @Petza914 's comment just put my OCD into overdrive :-)
Check out this post from 2008 where a lot of people reported similar thing. I resurrected it when I first got my car.
https://rennlist.com/forums/997-foru...e-knock-2.html
Check out this post from 2008 where a lot of people reported similar thing. I resurrected it when I first got my car.
https://rennlist.com/forums/997-foru...e-knock-2.html
#11
RL Community Team
Rennlist Member
Rennlist Member
I had another thought on this - is it only happening on cars with the factory airbox? I'm wondering if it is the Helmholz resonator in the airbox snapping shut upon throttle blip due to the immediate increase in air requirement from the quick throttle press. Someone with an automotive stethescope could put it on the resonator in their airbox while someone else blips the throttle and see what they learn.
I have never heard this in either of my 997.1 C2S cars and I'm wondering if that's because I don't run the stock airbox - the supercharged car has a Fabspeed J-Pipe intake and the other has the Evoms, which is what got me thinking about the resonator in the stock airbox.
I have never heard this in either of my 997.1 C2S cars and I'm wondering if that's because I don't run the stock airbox - the supercharged car has a Fabspeed J-Pipe intake and the other has the Evoms, which is what got me thinking about the resonator in the stock airbox.
Last edited by Petza914; 09-09-2019 at 01:27 PM.
#13
RL Community Team
Rennlist Member
Rennlist Member