NC14GT

With gas getting stupid high I was thinking of using 87 regular (like the owner's manual states for my '07 GT/CS) but I don't want 'pinging' or issues after using 89 octane for 15 years. Will the computer still accept this change after such a long period?
Why was I using 89?? The dealership said it wouldn't hurt, and it prevents getting weak or bad 87 fuel. Zero issues over all this time so I'm not sure if saving $4.00 per fill-up is even worth considering.

Bert

As I understand it, the 2007 ECU does not learn or adjust for octane in any way. It is tuned to run on 87 without major pinging; and if the knock sensors hear any pinging, it will pull timing to stop the pinging.

So "yes-ish" -- as I understand it, there should be no problem.

m05fastbackGT

This providing your running either the stock tune or aftermarket tune programmed to run 87 octane fuel.

houtex

If you wanna go a little overboard, go disconnect the battery for 20 minutes after you get 87 in the thing. Clean your MAF and throttle body. Reconnect battery, get in car, turn on, DO NOT start, push throttle to the floor slowly over 5 seconds. Release, start car, go drive for 10 miles mixed traffic, no faster than 50. There ya go, all 'relearned'. The computer does have long term fuel strategies based on various reasons, so if you're wanting the best solution to flipping to 87, this would put it back to base everything and then 'relearn' for the cheap fuel. If there's anything to relearn/train for by the different fuels in the first place, but best chance and all that, eh?

The 87 will absolutely ping/knock. You can't avoid it. The computer's not tuned all that well for the lesser octane, but it's enough that it won't get hurt by it. It'll just annoy. Also, the the lesser octane will mean lesser power. Which means that you will unconsciously use more throttle to overcome that missing power... and your MPG will suffer a little for it. At least, that's my experience. All the dollars gained by using 87 went out the window because of that for me, it was literally a wash... but then that was also different times and different gas prices.

If any of that means anything/helps/allays fears/makes sense/I should probably just not have posted/shut up already houtex/ok... fine...

NC14GT

Thanks for the replies guys. it's appreciated. I am 100% stock. The only thing ever added to the car was the Shaker (dealer installed when car was new) which affects nothing as far as fuel.
Since I'm on the topic, has anyone else been using 89 instead of the 87 recommended in the owner's manual??