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Old 04-03-2015, 01:55 PM   #1
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fuel question?

I sold my 00 boxy base to a friend a couple of days ago. I told him to use only premium unleaded in the car. he asked me if he could use regular unleaded, my response was only in a time of emergency.

so to the question, with the 11.5 c/r of the engine, if one were to use regular unleaded, what would happen? there is a knock sensor on the engine. would the ecu recurve the ignition to compensate or would the engine self destruct due to detonation? I have made some inquiries amongst friends locally, but no one could give a definitive answer (most didn't even know what a knock sensor was).

so does anyone know?

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Old 04-03-2015, 02:33 PM   #2
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Originally Posted by rdass623 View Post
I sold my 00 boxy base to a friend a couple of days ago. I told him to use only premium unleaded in the car. he asked me if he could use regular unleaded, my response was only in a time of emergency.

so to the question, with the 11.5 c/r of the engine, if one were to use regular unleaded, what would happen? there is a knock sensor on the engine. would the ecu recurve the ignition to compensate or would the engine self destruct due to detonation? I have made some inquiries amongst friends locally, but no one could give a definitive answer (most didn't even know what a knock sensor was).

so does anyone know?
The car's DME would respond by reducing the ignition timing a bit and altering the fuel curves to try and prevent pre-ignition and/or detonation from occurring. Most noticeable impact would be the car would feel down on power.
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Old 04-03-2015, 05:38 PM   #3
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Tell your friend not to be a cheap skate. If prem is $0.50 / gal more than reg, you'd spend an extra $8 per fill-up if your car was totally empty. If he can't afford $8 every cpl of weeks, then he can't afford a Boxster.
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Old 04-03-2015, 06:27 PM   #4
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Tell your friend not to be a cheap skate. If prem is $0.50 / gal more than reg, you'd spend an extra $8 per fill-up if your car was totally empty. If he can't afford $8 every cpl of weeks, then he can't afford a Boxster.
True that. I'll even add 104 Octane Boost with complete fuel system cleaner every 3rd fill up and CRC complete fuel system cleaner every oil change and my car is a daily driver.
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Old 04-03-2015, 08:37 PM   #5
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thanks for the replies, it was not an economic question, as much a operational question. thanks jfp, that was the answer I was looking for.

from my experience, some cars' ecu would not pull timing and richen the afr, thus leading to destruction of the engine. the question was just simply to ascertain whether it would be acceptable in an emergency situation.

by the way, living in an area which has the occasional hurricane and mandatory evacuations, sometimes the availability of specific fuels is not an option..
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Old 04-03-2015, 08:41 PM   #6
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Originally Posted by rdass623 View Post
thanks for the replies, it was not an economic question, as much a operational question. thanks jfp, that was the answer I was looking for.

from my experience, some cars' ecu would not pull timing and richen the afr, thus leading to destruction of the engine. the question was just simply to ascertain whether it would be acceptable in an emergency situation.

by the way, living in an area which has the occasional hurricane and mandatory evacuations, sometimes the availability of specific fuels is not an option..
Exactly....there are a number of places where you just can't get the good octane. Lots of threads about the fuel debate - most seem to acknowledge that you aren't going to hurt the car with regular, but the premium will make it purr of so much better!

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