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Thread: CXL 2.0 Turbo Spark Knock Reply to Thread
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  Topic Review (Newest First)
09-19-2012 04:40 PM
Harshman Never had the knock issue. Started running the higher octane and have gotten better pick-up and gas mileage. Gained about 1.5 or mpg over the 87 octane.
09-18-2012 09:51 PM
MyWifeIsaTurboJunkie I've been reading on the camaro5 forum that the computer Basiclly has a high octane spark and a low octane spark. If the engine has ran less than 91 octane it switches to low octane spark and doesn't come out of it untill it's manually reset by pulling 2 specific fuses or disconnecting the battery (most are saying let it sit about 3 hours before reconnecting).

They noticed a tremendous gain by doing this and increase in fuel economy!

Is there anything like this for the turbo regals. My wife's car had 87 put in from the dealer when purchased new and it runs like crap at idle 18k miles later still runs like crap and all we ever put in is 92/3 octane. Dealer acknowledges the issues but says they all do just like the "wheel hop feeling on take off no matter how you do it easy and steady or leaving from a drag tree" and there's no repair for either on that note... Damn lemon
03-24-2012 08:29 PM
fbrr ...
02-03-2012 05:18 PM
GNowner It actually isn't a mis-fire it is the fuel detonating before the engine is in the right position as far as timing goes. Basically the spark plugs are not what is igniting the fuel. When this happens the engine will retard the timing. The biggest danger is to the head gasket. Too much detonation will cause the head gasket to blow.

The first thing you should try is some fuel treatment. If you have a carbon build up inside the cylinder it may remain hot enough to ignite the fuel. I am able to run 87 octane fuel in our 2011 Regal but I only by gas from certain gas stations. I tend to stay away from the old run down stations just because if the the building and pumps are old the tanks will probably be old and leaking as well. You wouldn't eat at a old run down restaurant would you?

E85 will take care of this but you will lose fuel economy and it is harder to find is some areas. Another fix is to run fuel with higher octane or get a methanol/alcohol or water injection system. I run a alkycontrol system on my Grand National. This allows me to run 24psi of boost with out the knock. Without the methanol the car will only handle 18psi. In the older Turbo Regals we run a 160 degree thermostat to help keep the engine temps down and that is why Buick has the newer ones running at 185 degrees. We have found in the older Regals that they have less knock and make more power between 160 and 180 degrees.

Now to the scarier thought. Your fuel pump may not be putting out enough volume. Your fuel pressure should raise one psi per one pound of boost. If not it will cause a lean condition which will cause knock as well. Forced induction is great when it is working but when there is a problem it sucks. I am speaking from experience.

Like I said above, try some fuel treatments and get a higher quality of fuel from a quality gas station.

With these cars it could be a million things causing knock but this is the easiest thing you can try.
01-27-2012 02:03 PM
royal_regal That interesting from the OP who is getting a knock! and the guy running e85 as well!, well i guess just stick with whatever your dealer is telling you to run.
01-24-2012 10:04 PM
bpwilmoth I've got over 5k on my T05. The dealer told me to run regular, so I did for a month, then found posts here about running super. My car runs a lot better on super.
01-24-2012 07:11 PM
No Knock

Only have 700 miles on my T06. Haven't noticed a knock, but since I brought it home from the dealer with a full tank of gas (regular I'm guessing), I've been topping of with 89 just to be safe. Hate to go to premium on a regular basis if I don't have to. Don't really drive the car that hard....yet.
10-03-2011 04:22 PM
Turbogirl I have tried 93, 89 and 87 over 2500 miles. The car runs like shit on 87 so I run 89 and it feels the same as when I run 93. So 89 is it for me.
09-11-2011 08:20 PM
thetoys Still on my first tank of gas from the dealer...I hear the knock under light acceleration... I've put in a few top ups with Premium but I can still hear it.

I'm going to burn it all off and put in full tank of Shell 91.

Has anyone tried 89? does it still knock?

What is the difference in fuel economy between the octanes?
08-04-2011 01:24 PM
motorcityregalturbo dont let the flex fuel badge fool you - that doesnt mean you can throw whatever you want into the tank.

e85, while inefficient and impotent, actually has a high octane rating so it wont produce knock. while you can get better performance from regular or midgrade than e85 youre still prone to engine knock. i dont think its too common to experience engine knock when putting reg into your 2.0L turbo but i just use premium to be safe and get the most out of the engine.
06-26-2011 09:32 AM
Quicksilver I just rolled over 5K mi and have not had any problems with spark knock. I have experimented with 87 and higher octane and have not seen any notable difference in performance, so I have stuck with 87.
06-22-2011 01:23 PM
DeanPM I'm going to use one tank on Premium and then a tank of 87 and see what happens. I only have 2200km on it.
06-16-2011 05:27 PM
royal_regal I guess it could run on regular but having the knock and your motor mis-firing inst healthy as all so i would just stick with premium fuel and just have a healthier motor!
06-10-2011 03:12 PM
leroyk I too have notice the slight knock under light acceleration. Well it was nice dream filling the tank with reg unleaded for one month. Back to premium
06-06-2011 09:33 PM
Originally Posted by carnut View Post

If the vehicle has the 2.0L L4 engine
(VIN Code V), use premium
unleaded gasoline with a posted
octane rating of 91 or higher.
You can also use regular unleaded
gasoline rated at 87 octane or
higher, but the vehicle's acceleration
could be slightly reduced, and a
slight audible knocking noise,
commonly referred to as spark
knock, might be heard.This is from the manual on page 9-45 .
Hope this answers your question... I only use Premium and have had no problems with knock...
Thank you for the insight.
As usual the sales people want to sell the car, even when I asked the simple question before ordering will this thing run a regular fuel ok?

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