Do I need a retune?

[gashkerwin]

So I had my car out a few weeks ago, and its currently running a custom tune for 93 octane, and to make use of my mods. I needed gas, and I was in an area where I've never been before, and the only gas station I found only had 87. I only put a small amount in, just enough till I could get some real gas where I knew there'd be a station.

Well, now the car isn't running all that well. It seems to be down on power, based on the butt dyno, and doesn't quite idle right, even though I've run a full tank of 93 through it since the issues.

It has been particularly both hot and humid around here lately, neither of which are particularly conducive to cars running great and making big power.

So, do I need a retune (or hopefully to just get my tuner to re-apply the tune he put on it), or am I just being paranoid?

[pajeff02]

Octane indicates gasoline's resistance to pre-ignition -- a/k/a spark knock. I think it was Car Craft a couple of months ago that dyno tested various grades of gasoline and really found no difference in power levels. With lower octane gasoline, keep your foot out of it under load and you should be fine. The LS motors automatically pull timing if spark knock is detected. This could be why you think your car is not running up to par.

Now having said all that -- some motors just seem to run better on certain brands of fuel. Can't really say why, and it could all just be what people think, but that is what has been said on here. Also, dirty combustion chambers and fuel delivery/spark issues can all excacerbate pre-ignition problems.

[garygnu65]

never use 104 octane boost it gums things up . use some injector cleaner and some unleaded premium gas. you might have some water in you tank rite now,use some fuel drying additive .