[20v] 7A Fuel Grade?

Doug Macy dmacy1 at atlanticbb.net
Wed Dec 5 15:54:30 PST 2007

I think you will lose power because of the knock sensors and efi being
optimized for highest power with premium fuel.

If the lower octane creates ping or knock the ecu retards the timing till it
stops knocking and you will lose power. My understanding is that the ecu
will advance timing until knock sensors report a ping and then retard it a
little bit below the threshold to give us max power with the fuel (and other
conditions like air density, ambient temp, etc.)

Head gasket failure sounds like an odd result from using lower octane fuel.
Sets my BS indicator off!

Factory say "premium recommended for maximum performance"

I'd say you are fine to run regular if you don't mind the (temporary) power
loss, I have used regular on long interstate trips when the load is always
light to save a few bucks.

> -----Original Message-----
> From: 20v-bounces at audifans.com [mailto:20v-bounces at audifans.com]On
> Behalf Of Doug Johnson
> Sent: Wednesday, December 05, 2007 5:32 PM
> To: 20v; 20v at audifans.com
> Subject: [20v] 7A Fuel Grade?
> In my past two 7a CQs I've used regulate fuel with R+M/2 octane
> of 87, but a friend recently told me that using this grade of
> fuel can lead to failure of the head gasket.
> So, is it true that I NEED to use premium fuel in the 7A engine?
> Thanks,~ Doug
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