Alpha N 93 Octane Tune with 91 in Tank

[Deen HK]

Hi everyone. Bought an M3 with a turner csl airbox and an active auto alpha n 91 tune since the car is in Cali. The PO has flashed it to a 93 tune since the car is coming back to the east coast. It has about half a tank of 91 still in it. Am I safe to dilute the current 91 with 93 and drive with the 93 tune?

[EthanolTurbo]

Hi everyone. Bought an M3 with a tuner csl airbox and an active auto alpha n 91 tune since the car is in Cali. The PO has flashed it to a 93 tune since the car is coming back to the east coast. It has about half a tank of 91 still in it. Am I safe to dilute the current 91 with 93 and drive with the 93 tune?

Buy some octane booster at a parts store to be safe.

[Sharocks]

What he said ^

[repoman89]

It would be fine if they didn’t turn the knock sensors way down and go crazy with ignition timing like many aftermarket tunes do. Octane booster to be safe as other posters have recommended. I think it’d be fine either way unless the tune is otherwise unusable and unsafe.

[Deen HK]

Thanks all

[bmw m3 s50]

It would be fine if they didn’t turn the knock sensors way down and go crazy with ignition timing like many aftermarket tunes do. Octane booster to be safe as other posters have recommended. I think it’d be fine either way unless the tune is otherwise unusable and unsafe.

I was going to mention this. It depends on the tune. If a reputable tuner tuned the car they should have built in some form of safety parameters for these types of situations.

As others also mentioned, you could pick up octane boost to be safe.

Also drive the car normally, and don't drive aggressively until you can get the right gas or get it retuned for 91.

[Deen HK]

I was going to mention this. It depends on the tune. If a reputable tuner tuned the car they should have built in some form of safety parameters for these types of situations.

As others also mentioned, you could pick up octane boost to be safe.

Also drive the car normally, and don't drive aggressively until you can get the right gas or get it retuned for 91.

Update: filled the other half with 93 and put some octane booster in it. Every now and then the car will go into limp mode and won’t rev past 3k. Assuming it’s the lesser octane gas flowing through? It’ll go out of limp mode and be fine after, driving it conservatively until I’m sure all the gas is fresh 93

[Slideways]

Update: filled the other half with 93 and put some octane booster in it. Every now and then the car will go into limp mode and won’t rev past 3k. Assuming it’s the lesser octane gas flowing through? It’ll go out of limp mode and be fine after, driving it conservatively until I’m sure all the gas is fresh 93

You might want to scan it for codes; otherwise, you'll have to have someone look at that tune. Octane should not throw it into limp mode.

[Deen HK]

No EML light or codes on my scanner. Will buy a cheap windows laptop and scan with INPA