Engine Knock

Edgy01 · 01-13-2007, 02:33 AM

Is anyone else hearing the common sound of engine knocking (at least starting to) when you accelerate with the typical fuel we find in California (91 octane)? I hear it and then it goes away,--like the Vario-Valve is detuning actively to adjust. Maybe I'm not describing it well, but it sure sounds like that engine knock sound I used to hear years ago. Obviously, it doesn't last long,--maybe a second or so.

micgreeny · 01-13-2007, 02:40 AM

yes, I know what your talking about. mine has done that from day one.

ChrisF · 01-13-2007, 03:06 AM

mine did it when I first bought it, but I immediately put in a tank of Unocal 91 one and no sounds since.

gweedo911 · 01-13-2007, 10:10 AM

mine has been doing it for a while....

CharlieJr · 01-13-2007, 01:49 PM

Is this different than the dreaded "hesitation" problem??

ChipAZ · 01-13-2007, 02:40 PM

I avoid getting gas in Calf. at all costs.

cmoss · 01-13-2007, 03:41 PM

Quote:

Originally Posted by ChipAZ

I avoid getting gas in Calf. at all costs.

easy to do in tucson

avdiscolo · 02-20-2007, 11:07 AM

I just started noticing this in my '06 C2S after major engine work (replaced head gasket). The knocking appears very infrequently. In fact, for me it seems that it happens between shifts and *not* under load. I have not been able to reproduce this under load at any time.

I always use 92 octane gas from either Chevron or 76 here in WA.

diverdan · 02-21-2007, 03:29 PM

No problems on Chevron 92 octane.
I do have some rattling when the car is first started cold in the morning, but that goes away after idling about 5 seconds.

rcg412 · 02-21-2007, 03:39 PM

they replace head gaskets in 996/997s... thought it was an engine replacement?

Stephenkng · 02-21-2007, 03:48 PM

Where can you get Chevron 92 in Bay area???

cvazquez · 02-21-2007, 03:50 PM

Try adding half a bottle of octane booster to a full tank of gas or change your gasoline station.

diverdan · 02-21-2007, 04:57 PM

Quote:

Originally Posted by Stephenkng

Where can you get Chevron 92 in Bay area???

I usually get mine at the Chevron at Peninsula and Delware in San Mateo.

Stephenkng · 02-21-2007, 05:08 PM

Thanks. I may want to try that since I work in So. San Francisco.

dasams · 02-21-2007, 07:27 PM

As suggested by another poster, please add octane booster and let us know whether the sound goes away. If confirmed, this suggests to me that CA cars should get ECU updates to detune to 91 octane. After all, you aren't doing your engine any favors even if the knocking is very brief.

Such a shame...

01-13-2007, 02:33 AM	#1
Edgy01 Poseur Rennlist Member Join Date: Nov 2005 Location: Santa Barbara, CA Posts: 9,938	Engine Knock Is anyone else hearing the common sound of engine knocking (at least starting to) when you accelerate with the typical fuel we find in California (91 octane)? I hear it and then it goes away,--like the Vario-Valve is detuning actively to adjust. Maybe I'm not describing it well, but it sure sounds like that engine knock sound I used to hear years ago. Obviously, it doesn't last long,--maybe a second or so. __________________ Dan 06 997S PCCB Hard-Top Cabrio Turq. Blue, Nat. Brn Leather http://www.rennteam.com/photopost/sh...00&ppuser=8756

01-13-2007, 10:10 AM	#4
gweedo911 Addict Rennlist Member Join Date: May 2006 Location: Maryland Posts: 312	mine has been doing it for a while.... __________________ guido 997 C2 Atlas Grey 997 GT3

02-21-2007, 03:50 PM	#12
cvazquez Addict Rennlist Member Join Date: Mar 2006 Location: Orlando, FL Posts: 1,114	Try adding half a bottle of octane booster to a full tank of gas or change your gasoline station. __________________ 2006 Porsche 997 C2 Coupe 2006 Lexus GS300 (wifes) 1995 993 (sold) 1990 964 (sold)

02-21-2007, 07:27 PM	#15
dasams User Join Date: Feb 2005 Location: SF Bay Area Posts: 144	Test with Ocatane Booster As suggested by another poster, please add octane booster and let us know whether the sound goes away. If confirmed, this suggests to me that CA cars should get ECU updates to detune to 91 octane. After all, you aren't doing your engine any favors even if the knocking is very brief. Such a shame...

01-13-2007, 02:40 AM	#2
micgreeny User Join Date: Apr 2006 Location: Pleasant hill , Ca,USA Posts: 116	yes, I know what your talking about. mine has done that from day one.

01-13-2007, 03:06 AM	#3
ChrisF Addict Rennlist Member Join Date: Dec 2005 Location: SoCal & Vancouver Posts: 232	mine did it when I first bought it, but I immediately put in a tank of Unocal 91 one and no sounds since.

01-13-2007, 01:49 PM	#5
CharlieJr Addict Rennlist Member Join Date: Aug 2006 Posts: 924	Is this different than the dreaded "hesitation" problem??

01-13-2007, 02:40 PM	#6
ChipAZ Addict Rennlist Member Join Date: Aug 2006 Location: Capitan< New Mexico Posts: 718	I avoid getting gas in Calf. at all costs.

02-20-2007, 11:07 AM	#8
avdiscolo User Join Date: Mar 2006 Location: WA, USA Posts: 65	I just started noticing this in my '06 C2S after major engine work (replaced head gasket). The knocking appears very infrequently. In fact, for me it seems that it happens between shifts and not under load. I have not been able to reproduce this under load at any time. I always use 92 octane gas from either Chevron or 76 here in WA.

02-21-2007, 03:29 PM	#9
diverdan User Join Date: Dec 2006 Location: Burlingame, CA Posts: 36	No problems on Chevron 92 octane. I do have some rattling when the car is first started cold in the morning, but that goes away after idling about 5 seconds.

02-21-2007, 03:39 PM	#10
rcg412 Addict Rennlist Member Join Date: Sep 2005 Location: NYC and Summit, NJ Posts: 839	they replace head gaskets in 996/997s... thought it was an engine replacement?

02-21-2007, 03:48 PM	#11
Stephenkng User Join Date: Sep 2005 Location: San Francisco Posts: 461	Where can you get Chevron 92 in Bay area???

02-21-2007, 05:08 PM	#14
Stephenkng User Join Date: Sep 2005 Location: San Francisco Posts: 461	Thanks. I may want to try that since I work in So. San Francisco.