luxury cars

[Funyuns101]

Originally posted by: Arkaign
ZV is 100% right here. The whole point of a car's modern fuel management system w/sensors and computers is to adjust the mixture on the fly to compensate for the octane/richness/etc of the fuel and air that is being used by the motor. The EGR system also has to function correctly in this regard. Running low octane gas just causes your car's systems to adjust to the different levels it needs to operate safely and cleanly.

My Brother's TL idles and runs smooth as silk on regular 87 octane pump gas. He gets a fraction higher mileage and power with 93, but he doesn't bother 99% of the time. He still gets about 27mpg highway, and around 19 city with the 87 octane, and he doesn't have a lead foot.

so basically these parts just died from being old? not because of slightly cheaper gas?

 

[Sunrise089]

Originally posted by: Arkaign
ZV is 100% right here. The whole point of a car's modern fuel management system w/sensors and computers is to adjust the mixture on the fly to compensate for the octane/richness/etc of the fuel and air that is being used by the motor. The EGR system also has to function correctly in this regard. Running low octane gas just causes your car's systems to adjust to the different levels it needs to operate safely and cleanly.

My Brother's TL idles and runs smooth as silk on regular 87 octane pump gas. He gets a fraction higher mileage and power with 93, but he doesn't bother 99% of the time. He still gets about 27mpg highway, and around 19 city with the 87 octane, and he doesn't have a lead foot.

I think this is essentially correct, BUT I also think the horsepower should be down considerably. Now of course if you're never on the gas it won't matter, but there is a reason why almost all engines that make lots of power per liter use high compression, and high compression does require higher octane unless timing/spark is changed. Even if the sensor is working fine, the output of the engine should be noticeably down. The question in the TL example is why bother with the luxury car if the 20 cent extra cost is really that unfordable. I know it isn't necessary, but neither then is a high-output V6.

 

[Zenmervolt]

Originally posted by: Nyati13
The knock sensor is a vibration sensor, if it is being activated that means there is a vibration present in the engine that would not be there if the correct fuel was being used.

Vibration present = not 'perfectly' safe. period.

Yeah, and driving the car at all causes the wheel bearings to wear out because of the wheels spinning. That's a ridiculous argument.

An engine is always vibrating if it's running. Using lower octane will never shorten the service life of the knock sensor. It's a mechano-electrical part that is subject to typical manufacturing tolerances and some of them are just plain going to fail early. That's just the way it is. Running 87 octane will have zero meaningful effect on the service life of the part. Zip. Zilch. Nada.

ZV

 

[Zenmervolt]

Originally posted by: Sunrise089
I think this is essentially correct, BUT I also think the horsepower should be down considerably. Now of course if you're never on the gas it won't matter, but there is a reason why almost all engines that make lots of power per liter use high compression, and high compression does require higher octane unless timing/spark is changed. Even if the sensor is working fine, the output of the engine should be noticeably down. The question in the TL example is why bother with the luxury car if the 20 cent extra cost is really that unfordable. I know it isn't necessary, but neither then is a high-output V6.

Under normal conditions, you lose less than 5% of rated power (assuming a non-turbocharged engine). Worst case scenario (heavy load, hot, humid weather, low RPM, lots of throttle) you may lose 15%.

Most drivers will never notice the difference.

ZV

 

[Zenmervolt]

Originally posted by: Funyuns101
so basically these parts just died from being old? not because of slightly cheaper gas?

Yes.

ZV