FLA02TA

iTrader: (5)

Hey, they might not be the brightest bulb on the tree, but there's no need to sling insults at people.

Hehe

BlueSix

You could still get excessive carbon build up even if you aren't revving the motor out. I'd stick to a minimum 91 octane, regardless.

Phil8616

iTrader: (11)

Like I said thanks to the people who helped...I realized I made a mistake, the thread should be dead. I was asking for help not bashing.

Luna

iTrader: (6)

I think its psychologically impossible for anyone of sound mind to keep a vehicle like this under 3500 rpms no matter what, I think I got WOT at least twice every time I drive it

mark306ci

on a recent 3000 mile trip, 89 octane gave me the best MPG on an A4 with small mods (ssra,free mods, etc). 31.5 mpg

previous owner ran the car on 87 octane for over 2 years and 20k miles. the PCM got used to it and probably kept it at the low timing table. no noticeable knock during WOT. maybe a little if WOT uphill.

when i switched to 93 octane, there was an immediate loss in MPG. once the PCM got used to it...the MPG went back up a little, but not as good as 87 octane.

i'll be doing another 3000 mile trip w/i a week to confirm.

ss rally red

iTrader: (8)

This is a complete statement,please explain in detail how a fuel that is only 4 octane points less than premium will cause carbon build up and ruin an engine,cant wait to hear this one

RevGTO

iTrader: (12)

I was heading out for a long distance trip recently, and I thought, "maybe I should just put in 89 ... steady throttle all the way, won't hurt anything." But I couldn't bring myself to do it ... especially at less than a buck and a half a fill-up.

ss rally red

iTrader: (8)

Guys why does GM have the PCM have high and low octane tables? Is it because they KNOW in certain parts of the US and other country's that cars with LS1's installed may never have the advantage of using 93+ octane?? No dought that timing is optimized with premium fuel but geez their is no way a tank(s) of mid grade is going to cause any long term effects

NYC FRANK

jaberwaki

save 3 bucks chance blowing a 30,000 cars motor.... hey that makes perfect sence..

Original poster i am not bashing you... There is obiously still members on this board that think the pcm will save them because we all know these cars NEVER have any pcm troubles...

hey if the pcm starts retarding the timeing because of knock, guess what has to be happening already for this to happen?

and what do you call this knock boys and girls??? its call preignition or detonation....
Anyone here wanna tell me the exact amount of time your motor can detonate without causing any lasting effects???

thats right... nobody can... you know why??? because it all depends on 100000 x factors, it could damage it in less the then a second, it could hold out a long time.
ever play russian roulete?

its 3 bucks... check the cushons of your couch, you might find 3 bucks in change there.

but hey.... who cares... its just a car right?

mark306ci

but most of our cars are nortorious for knocking on 93 octane also.

the oldguy who sold me the car said that he's been running 87 octane for 20k miles with no problems. on my first full tank with 87 octane (from the previous owner), i was expecting lots of knocking. hardly any (except WOT uphill). the PCM was settled at the low timing tables.

then when i switched to 93 octane....performance gradually increased...so i guess the PCM was reverting back to the high timing tables.....after a few months of 93 octane....still some knocking (esp. WOT uphill...summertime=worse)...about the same as it was with 87 octane & low timing.

conclusion....most LS1s needs a dynotune to rid of most or all of the slight knocking (btw, i did all the wires, colder plugs, seafoam, etc....what helped most was setting the fan to come on earlier with HP Tuners)