Consequences of running low-octane fuel with a performance chip?

[Jay 535i]

What will happen?

[Kalevera]

It will cause pre-detonation. AkA, pinging, which is a bad thing to have happen over extended periods of use.

best, whit

[632 Regal]

Detonation or preignition which is like a sledge hammer pounding the tops of the pistons. This can bust the pistons, cause fractures in them, the rings, ring lands and hammer the bearings out.
In the racecar you can see the effects (if it doesnt blow the crank onto the track) by looking at where the main bearing caps meet the block, will look like a ball peen hammer went to town on the surface.

[gtopaul]

What will happen?

Bad things. I've also got a chipped car and have been having some trouble finding premium so I stocked up on a couple of bottles of convertor safe octane booster to use in case regular is all that's available. Not a cost saving move to be sure but more of an availability issue.

Paul

[PhilipJCaputo]

it isn't worth it.... you might feel like your saving a lot of money, but assuming 20 cents more for premium, you only going to cut your gas bill by 6% at 3/gal.

If gas was 1/gal, and premium was 1.20/gal, then you'd be saving yourself 20%

the higher fuel prices go, the more economical it is to run premium!

[Jay 535i]

I wasn't considering doing it, just wondering what would happen.

'Knocking' is the answer I expected, but don't our cars have electronic gizmos to prevent that? I know most modern cars have the ability to adapt to low quality fuel, because in some parts of the world that's all that's available.

Does installing an aftermarket chip somehow remove or reduce the effectiveness of these safeguards?

[Jeff N.]

No knock sensor on the 535. The later model cars with the Motronic 3.1 do have sensors (M50, M60 etc).

I've had OK luck running mid grade gas on chipped cars. Depends on the chip, your state of tune, outside temp (hot = bad) etc. More than likely the car won't knock but it will ping. Pinging is not as bad as knocking but still something you don't want to have.

Jeff

[stx133]

the 540 has got a stack of knock sensors shown on the wiring diags.. will that retart the timing and 'override' a chip?

[Garlic Breath]

it isn't worth it.... you might feel like your saving a lot of money, but assuming 20 cents more for premium, you only going to cut your gas bill by 6% at 3/gal.

If gas was 1/gal, and premium was 1.20/gal, then you'd be saving yourself 20%

the higher fuel prices go, the more economical it is to run premium!

That's a great point Mr. Caputo.