Whats Your Octane?
13-Aug-2006, 01:36 PM
#41
Registered User
Join Date: Mar 2004
Posts: 1,730
Originally posted by electronblue
Car runs like poo poo with 91 octane though and the Prelude is a premium only car. I shouldn't be wasting fuel if that is the case, as the OBD2 computer will sense the unburned fuel at the o2 sensor in the header before the cat. Technically, it should lean me out not throw in more fuel.
Car runs like poo poo with 91 octane though and the Prelude is a premium only car. I shouldn't be wasting fuel if that is the case, as the OBD2 computer will sense the unburned fuel at the o2 sensor in the header before the cat. Technically, it should lean me out not throw in more fuel.
if there is too much oxygen (such as in the case of unburnt fuel - unused oxygen), the ECU will dump more fuel into the combustion chamber, and richen up the mixture in order to reduce oxygen levels at the exhaust.
which is exactly what it is doing - unburnt fuel = too much oxygen = more fuel dumped into the combustion chamber = decreased fuel efficiency
13-Aug-2006, 04:18 PM
#46
Originally posted by ERTW
no, oxygen sensors do not sense unburnt fuel, they sense oxygen.
if there is too much oxygen (such as in the case of unburnt fuel - unused oxygen), the ECU will dump more fuel into the combustion chamber, and richen up the mixture in order to reduce oxygen levels at the exhaust.
which is exactly what it is doing - unburnt fuel = too much oxygen = more fuel dumped into the combustion chamber = decreased fuel efficiency
no, oxygen sensors do not sense unburnt fuel, they sense oxygen.
if there is too much oxygen (such as in the case of unburnt fuel - unused oxygen), the ECU will dump more fuel into the combustion chamber, and richen up the mixture in order to reduce oxygen levels at the exhaust.
which is exactly what it is doing - unburnt fuel = too much oxygen = more fuel dumped into the combustion chamber = decreased fuel efficiency
If the cat was not burning the mixture, the sensor would blow inefficient cat code. Thus zeeman is right the sensors are useless except for maybe emission purposes.
13-Aug-2006, 06:02 PM
#47
Registered User
Join Date: Mar 2004
Posts: 1,730
no
the cat is not burning any unburnt fuel, the catalysts in the converter neutralize some of the more harmful emmissions
the post-cat O2 sensor does just what the pre-cat O2 sensor does.. it measures oxygen and compares it to the pre-cat reading
I;m not arguing you shouldnt be using 94 octane.. just explaining the decreased fuel efficiency, in the end it is your car and your money
the cat is not burning any unburnt fuel, the catalysts in the converter neutralize some of the more harmful emmissions
the post-cat O2 sensor does just what the pre-cat O2 sensor does.. it measures oxygen and compares it to the pre-cat reading
I;m not arguing you shouldnt be using 94 octane.. just explaining the decreased fuel efficiency, in the end it is your car and your money
13-Aug-2006, 07:27 PM
#48
Originally posted by ERTW
no
the cat is not burning any unburnt fuel, the catalysts in the converter neutralize some of the more harmful emmissions
the post-cat O2 sensor does just what the pre-cat O2 sensor does.. it measures oxygen and compares it to the pre-cat reading
I;m not arguing you shouldnt be using 94 octane.. just explaining the decreased fuel efficiency, in the end it is your car and your money
no
the cat is not burning any unburnt fuel, the catalysts in the converter neutralize some of the more harmful emmissions
the post-cat O2 sensor does just what the pre-cat O2 sensor does.. it measures oxygen and compares it to the pre-cat reading
I;m not arguing you shouldnt be using 94 octane.. just explaining the decreased fuel efficiency, in the end it is your car and your money
Decreased fuel efficiency was minimal...it was only 25km drop/ approx 50L, from 475/50L to 450/50L when I first switched over 4 years ago. Actually its not a consistent drop because my last fill up showed 391.3km/38.82L. (I only know this because I just filled up. Paid $43.44 for gas.) Is the car more efficient now than when it was 4 years newer? My driving habit hasn't changed (other than I don't let it run until gas light anymore).
Actually now that your answering questions on the exhaust, does the unburnt fuel actually leave the exhaust into the atmosphere?? Why does the cat run soooo hot?? Sorry now I'm curious.
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