Hi,

Does anyone know if there are any items that would show up different over the OBD-2 datalogging when running 91 Octane and then when again running 100 Octane.

I thought maybe the ignition advance would change when running 100 Octane, but from some quick runs I have done I see no difference. Note, I did reset the ECU after filling up with 100 Octane, and III have now run over a 1/4 of a tank with the 100 Oct in there.

From watching my boost gauge I have noticed it is now holding higher boost with the 100 Oct - it now holds at 1.2 kg/cm2 wheras before it held at 1.1 kg/cm2. Even though it has been a lot hotter than normal here in So Cal over the last few days.

So does anyone know if anything loggable by the OBD-2 would logger higher / lower when gas quality changes ?

 

i've found no knocking... you can see knock by the dips in the timing when full boost hits under 91 octane... timing with 91 octane falls on its face slightly then very very slowly rises, with 94 octane no knock; timing drops underboost then begins to climb as it should while still under boost

 

The figures below are for a 4th gear pull at WOT on 91 Oct

2391 12
2621 9
2953 6
3445 5
3969 7
4445 7
4902 8
5336 8
5707 9
6055 10
6383 12
6695 13
6984 14
7262 15

So the dip you are talking about is the timing going from 12 degrees at 2391 rpm to 6 degrees at 3445 rpm ?