Accidentally filled the tank with 87 octane gas - now what?

[Ladykiller]

So I accidentally filled the tank with 87 octane gas (I think, but need to find my receipt to verify). So now what do I do? I put in about 10 gallons with Stabil to top it off for winter storage. Do I have to drain the tank? Or can I get away with adding a bottle of octane booster? My ZL1 says Premium Required (not recommended unfortunately for this instance).

[Happy_Dan]

You'll be fine. Use that up then when you put fresh gas in pull the fuses and let it sit a bit and it will relearn the good gas fuel curve

[BuddyLee]

Originally Posted by Ladykiller

So I accidentally filled the tank with 87 octane gas (I think, but need to find my receipt to verify). So now what do I do? I put in about 10 gallons with Stabil to top it off for winter storage. Do I have to drain the tank? Or can I get away with adding a bottle of octane booster? My ZL1 says Premium Required (not recommended unfortunately for this instance).

I would run the tank to empty and since Washington state is 92 fill your tank. In the evening pull fuse 5 and 20. Let your car sit over night. In the morning reinstall the fuses. If you do not pull those fuses your fuel octane sensor system will be forever stuck on the lower fuel is my understanding. I was lucky to find this out several months ago and had been driving the car since purchase 18 months earlier when I purchased it. Guaranteed at some point the car had been fueled with lower octane. It was a Hertz rental car is why I know that.

[102SS]

If your parking the car for the winter add your stabil and some octane booster.

When I parked my 3rd and 4th gens I would fire them up every few weeks and let the engine warm up at idle.

If you just idle it there is no load so there should be no knock after a winter of doing this you should be near 1/2 a tank then you get a jerry can and fill her back up with 93/94 or the 104 Sunoco you lucky guys get.

I think GM designed it to run on California 91 so you should be fine.

[RobZL1]

You'll be fine. Just baby it (low throttle input, no more than 50%) until you need to fill up again. It won't show knock unless you put it under load. So, don't put it under load, then get some 92 or 93 back in it next tank. To be clear, there is no fuel octane sensor- it just reacts to knock and lowers advance between a high and low spark table in the tune until it stops knocking.

[BuddyLee]

Originally Posted by Ladykiller

So I accidentally filled the tank with 87 octane gas (I think, but need to find my receipt to verify). So now what do I do? I put in about 10 gallons with Stabil to top it off for winter storage. Do I have to drain the tank? Or can I get away with adding a bottle of octane booster? My ZL1 says Premium Required (not recommended unfortunately for this instance).

This will show how and why you may want to reset your octane sensor for better octane utilization.

[Juiced1]

Toss some 100 octane in it to mix it back to 93. You can drive it fine, these cars have a low octane map with less timing. I wouldn't beat on it until you ran another tank through it.

[RobZL1]

Not that it really matters at this point, but again, there is no actual octane sensor for those that might care to understand what the ECM is actually doing.

There is a high octane spark advance map, and a low octane spark advance map. There is a "knock learn factor" coefficient that determines where the car operates between these two maps. That KLF is calculated based on repeated knock, when present. If there is no persistent knock, there is no KLF change, and no timing pulled.

Public service announcement.

[vinman]

Throw some octane boost in it or part it out, recaros?

[RyangAsh]

The house is a 1/4 mile from the E85 station, I guess I am lucky.

[Batmanntexas]

Originally Posted by Juiced1

Toss some 100 octane in it to mix it back to 93. You can drive it fine, these cars have a low octane map with less timing. I wouldn't beat on it until you ran another tank through it.

OP - My apologies for the thread jack---

Juiced1, Shouldn't you be responding to emails, voicemails, etc.? Completing RMA paperwork for wrong items delivered? You have time to surf car forums, but can't respond to paying customers?? WTF...

[ZMEnow]

Originally Posted by RobZL1

Not that it really matters at this point, but again, there is no actual octane sensor for those that might care to understand what the ECM is actually doing.

There is a high octane spark advance map, and a low octane spark advance map. There is a "knock learn factor" coefficient that determines where the car operates between these two maps. That KLF is calculated based on repeated knock, when present. If there is no persistent knock, there is no KLF change, and no timing pulled.

Public service announcement.

I don't think they get it but maybe i can help, ITS SELF LEARNING.

[PeteD]

Or maybe they do get it and realize that in the end, they do the same thing. They knock the computer down into the fuel map for the lower octane to prevent knock and so on......They are both "sensprs" and will do the same thing. Tell the computer what it needs to know to put it in the lower fuel map which then has to be manually reset

[RobZL1]

https://www.camaro5.com/forums/showt...=256551&page=4

Everything you need to know about knock learn factor as it applies to an LS3 or an LSA, complete with actual data before a tank of 87, and after, and then after a tank of 93 again.