Tuned on 93 octane, moving to area with 91

Mandingo

It's been a long *** time since I posted here!

So my Z was tuned on 93 octane by Uprev in Austin a few years ago. I'm moving to a new city for the next 3 years where the highest grade fuel available is 91. I don't have a 91 octane map to switch to.

Will the ECU adapt to the lower octane rating and pull timing until it is running safely? I'd rather not go back to Uprev to get a 91 octane map if I don't have to since they are 5 hours away and $ is tight.

Thanks for your wisdom folks

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Quicksilvers

I have seen this before with my time on the dyno. Tuning can get expensive when making changes to your Z often. With your current UpRev tune your ECU will not let your Z just self destruct. Your ECU will adapt and change the perimeters in your current 93 octane UpRev tune. Your ECU will notest almost instantly you are using 91 octane fuel not to worry. The ECU will pull timing as needed and you will more than likely notest a drop in power a specially after your engine reaches operating temperatures. My advice would be to run only top tier gasoline in your Z like (Chevron,Texaco,Shell etc.) as Nissan recommends only using top tier gasoline’s in all Nissan models not just the 370Z. If you do notest any detonation or spark knock just add a bottle of octane boost and pour gasoline in your tank at the same time. I have been using the NOS brand octane boost lately and notested a difference a specially on track days.

SouthArk370Z

What Quicksilvers said.

Could you save the current tune to disk, remote tune for 91, run for three years, reload "old" tune? Or would that still be too much money?

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Mandingo

Thanks Quicksilvers. Using a little octane booster is a good idea. I'll probably do that for peace of mind especially in the warmer months along with top tier gas.

Southark, that's a good thought too. I emailed Uprev yesterday to see what my options are and if this is even a problem worth fretting over. I'll post here when I get a response from em.

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Mandingo

Here's the email response I got from Uprev after asking them the same question with the same wording:

"The ecu will not adjust for octane your best bet is to get re tuned on the 91 octane."

I wonder if they mean performance will suffer on 91 octane so it's better to get retuned for that reason? I'll probably still just use octane booster instead of retune at this point.

Not the response I expected or wanted. Ha!

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Chuck33079

They mean there's a good chance the motor will be knocking, possibly beyond the capability of the ecu to self correct.

It all depends on what your tuner did. If it's a ragged edge tune on 93, running 91 is a bad idea. If it's a very conservative tune, you might be ok. Just save yourself the headache and have your tuner make a 91 map for you so you can switch between both as needed. They can probably email you one with minimal datalogging required.

The stuff sold as octane booster doesn't do jack **** 99% of the time. They're almost all snake oil. Sure, it says it'll raise the octane 5 points. Great. Now you're running 91.5. Yay. If you have to go the diy route, use toluene. But, after a year, you'll have spent more on octane boosters than a quick retune would have cost.

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Mandingo

Thanks Chuck. It was a conservative tune at Uprev HQ in Austin, but you're right. I'll feel much better just getting a 91 octane map.

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