Ok guys this might be a stupid question but here it goes. I got my tune last friday and its set of course to use 93 octane. I had 87 in the car and ive been slowly using it up so i can put 93 in the car. Now my question is since i have had 87 octane in did the computer detune itself so it does not harm the motor? Also, when i put 93 in soon will the computer retune its self and ill finally see the performance gain with the tune?

Thanks fellas.

It will probably take 2 tanks of 93 for the computer to completely learn the new fuel tables. Just be cool with it until all that 87 crap is gone. Then have some fun...

Ok, ive been already get on her a little bit though. My timing was totaly screwed up. I was suppoed to go up there with 93 but i had more then a half of tank of 87 left. Do you know think i should go back up there and have them redo the tune when i get my tank full of 93

Just fill it up now with 93 and use that going forward. Mixing it won't hurt anything, will just raise the octane a bit.

It should ping like hell at WOT. What kind of tune did you get? Just about all tuners out there push timing as high as possible without detonation then copy use those same settings on both High and Low Octane Tables preventing the use of anything but the Octane you requested.

I would like to know what kind of tune you got. It must have been a tune from another G8 GT as it wouldn't be possible to dyno tune for 93 with 87 in the tank.

Ya i thought the same thing. I think i will call up there 2marrow. Im going to fill up with 93 today and see what happens. Im worried that i messed up by getting the tune with 87 octane. Any other thoughts?

Ya i thought the same thing. I think i will call up there 2marrow. Im going to fill up with 93 today and see what happens. Im worried that i messed up by getting the tune with 87 octane. Any other thoughts?

I expect you'll be fine. Get the premium in there and it will probably continue to get better over the next week or however long it takes to work all the regular out.

I don't expect it did but if it had "de-tuned" itself, it should "re-tune" itself too maybe.

If it did permanently detune it would expose a huge drawback in the product; what if you were unable to get 93 and had to use 91 or 87 for one tankful? I don't expect this is the case and I'm sure Vector will reply on Monday.

Ok guys this might be a stupid question but here it goes. I got my tune last friday and its set of course to use 93 octane. I had 87 in the car and ive been slowly using it up so i can put 93 in the car. Now my question is since i have had 87 octane in did the computer detune itself so it does not harm the motor? Also, when i put 93 in soon will the computer retune its self and ill finally see the performance gain with the tune?

Thanks fellas.

You'll be fine, we leave all the stock protection mechanisms in place so that if you DO have to fill up in an emergecy or get bad gas you wont damage your engine.

Just about all tuners out there push timing as high as possible without detonation then copy use those same settings on both High and Low Octane Tables preventing the use of anything but the Octane you requested.


Some do that (we dont) when tuning but SHOULD put it back when they are done. If not thats about the WORST way to tune a car as there is no longer ANY variance for bad gas, mislabeled octane, water ECT. Things like this put ring lands in oil pans and should be avoided like the plague.

Told ya :)

Seriously, glad you got the answer that I expected you would get. I plan to invest in this soon too and was hopeful that my theory was right!

This is one of the reasons I'm so pleased with VMS. They told me in am e-mail earlier that 87 would be safe but MPG would be pretty bad. It was nice to know that bad gas or no place to get 93 would only cost gas money, not motor money.

Awesome! Thanks guys and VMS! Well im going now to fill up with 93. So now that 93 is going to be ran i should see the full potential of the tune correct?

You should be fine. Just make sure the 87 is gone. Even though Vector takes care of our engines in their tunes, you don't want to be flogging the car with 87 in it.

You should be fine. Just make sure the 87 is gone. Even though Vector takes care of our engines in their tunes, you don't want to be flogging the car with 87 in it.

Very good advice. I ran mine (87) down very low then filled with 92. I then drove without any WOT or heavy engine loads until that tank of 93 was almost gone then re-filled with 93 and let it RIP. I've never looked back (except to check for blue lights).

So when i put 93 in the car i should see a noticable difference then what i see now?

I didn't try mine for real until I had almost 2 full tanks of 93 run through it. I can't tell you if it had to learn or not. All I know is when I did nail it after filling the 3rd tank, I could feel the difference from the stock tune with 87.

I did get on it a couple of times with 87. (had to put a srt4 neon in its proper place). Hope i didnt damage anything :(

You should have heard it "knocking". As VMS said, the computer will just go into a low octane table so it doesn't hurt anything.

You should have heard it "knocking". As VMS said, the computer will just go into a low octane table so it doesn't hurt anything.

Ok. So after lets say 2 full tanks of 93 the computer will use the 93 octane table that VMS installed and i should be able to a performance increase over 87? Sorry for all the question just trying to figure this all out. Thanks.

You're fine. You have a performance increase.

Ok, thanks everyone!

You're fine.

I'll have to look out for you in Northville, my parents are down there so I'm in that area a lot. I haven't seen many others around...

Ok. So after lets say 2 full tanks of 93 the computer will use the 93 octane table that VMS installed and i should be able to a performance increase over 87? Sorry for all the question just trying to figure this all out. Thanks.

You're fine.

I'll have to look out for you in Northville, my parents are down there so I'm in that area a lot. I haven't seen many others around...


Ya im the only red g8 gt in northville so far. Ive seen 1 black one and the other black ive seen is the v6. Thanks for the help man.

From what I understand everytime the ECM detects a fill up (by the arm/float in the tank rising to the surface) it resets the assumed Octane.

1. When its reset does the ECM start with the High Octane Timing Table and work down...
2. Start in the middle between High and Low Octane...
or

3. Start with the Low Octane Table and work up...

I am just wondering how this works and "if" it takes a while to relearn.

From what I understand everytime the ECM detects a fill up (by the arm/float in the tank rising to the surface) it resets the assumed Octane.

1. When its reset does the ECM start with the High Octane Timing Table and work down...
2. Start in the middle between High and Low Octane...
or

3. Start with the Low Octane Table and work up...

I am just wondering how this works and "if" it takes a while to relearn.

That is a common misconception. The only way for the vehicle to go from the low octane table back to the high octane table is time. Once the engine detects no knock for a certain amount of run time it will slowly increase the amount of timing.
For example, in a new Z06 I just tuned it took about 4 days of driving every day.

Sounds to me like the thing to do is fill up with premium a few days before you get your tune, just to make sure al the regular is flushed out and then you won't have to worry about the timing retard due to knocking.

Sounds to me like the thing to do is fill up with premium a few days before you get your tune, just to make sure al the regular is flushed out and then you won't have to worry about the timing retard due to knocking.

That's exactly what I did. I was on my 3rd tank of 93 when I got tuned today.