2009 A4 TSI

urq urq at pacbell.net
Thu Jun 5 07:23:27 PDT 2014

... on the premium fuel economy myth:


I had heard years ago that lower octane fuel actually had more energy per
gallon, but I could not confirm that.  The article I copied included a few
other myths on fuel economy.

Nick, if your dealer really did say this I'd call BS ... the carbon buildup
was likely due to *cheap* gas without the cleaning additives that the more
expensive suppliers provide.  If you bought low octane from one of these
expensive sources it usually has the same additives as the higher octane
fuel.  BTW, you can have the carbon deposits cleaned at many service
stations ... or if you like WWII Naval exercises you can run a can of
Seafoam through your intake tract ...

Steve Buchholz

-----Original Message-----
From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com] On
Behalf Of Jeremiah Curry
Sent: Thursday, June 05, 2014 7:06 AM
To: Nick Lawrence; quattro at audifans.com
Subject: Re: 2009 A4 TSI

I had a 99 Passat and it started having a lot of trouble running.  Got to
the point where it would die at ide.  Took it to my Audi specialist and it 
was full of carbon buildup.  He said it was from not running premium.    Not

sure if that was true, but they were very good and I never had any trouble
again after I started using premium.  I had always figured since it was not
a turbo I could just use regular and it would retard timing if needed.

-----Original Message-----
From: Nick Lawrence
Sent: Thursday, June 5, 2014 7:50 AM
To: quattro at audifans.com
Subject: Re: 2009 A4 TSI

I also have trouble with this,   I would like to see a "real time"
timing display.    Does using regular instead of premium automatically
retard timing?  Or does the computer  have to sense knock then change
timing?      I personally haven't seen increased mpg using premium on my
cars. But I'm generally not on boost a lot.
Myth busters?

On 6/5/2014 8:37 AM, Paul Caouette wrote:
> OK!
> I can't help myself. Please look up the energy per unit volume of 
> "premium" vs "regular" gas.
> I don't believe it is the fuel.  It is the way it is packed into the 
> space where it is burned that increases the energy available. So, 
> higher compression allows more fuel and oxygen to get pushed into the 
> same volume awaiting that spark that lights it up. When a knock sensor 
> detects a pre-ignituon. (Due to lower grade fuel) it regards the 
> timing of the ignition. This will lead to less energy available in the 
> flame front. But I don't think there is any more energy in premium 
> gasoline. It is simply a better quality of the same stuff.
> Paul Caouette
> Sent from my iPhone

quattro mailing list

quattro mailing list

More information about the quattro mailing list