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For those who have to use low octane (cheap) gas.....

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Old Oct 20, 2003 | 04:16 PM
  #1  
LastBoyScout's Avatar
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For those who have to use low octane (cheap) gas.....

My mechanic had a 97 Max in the other day. The owner, an older lady, said she was getting crap for gas mileage, and that it was not acting the same as the day she bought it. Well, he checked the codes, and asked her all sorts of questions. Come to find out, she is running 87 octane aka regular unleaded, which in turn was causing her engine to knock.

His solution..... Unplug the battery and all the knock sensors and allow the ECU to clear. Then replug everything. He said that by doing this, when the ECU runs diagnostics on the sensor to find the fule octane rating and set the timing table, that it would in turn set it for the lower octane.

however, should you ever deside to switch to a higher octane, you will need to repeat this so that your ECU will compensate for the high octane.

Time consuming, but worth it for all you finacially challenged max owners out there.
Old Oct 20, 2003 | 04:32 PM
  #2  
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Originally Posted by LastBoyScout
My mechanic had a 97 Max in the other day. The owner, an older lady, said she was getting crap for gas mileage, and that it was not acting the same as the day she bought it. Well, he checked the codes, and asked her all sorts of questions. Come to find out, she is running 87 octane aka regular unleaded, which in turn was causing her engine to knock.

His solution..... Unplug the battery and all the knock sensors and allow the ECU to clear. Then replug everything. He said that by doing this, when the ECU runs diagnostics on the sensor to find the fule octane rating and set the timing table, that it would in turn set it for the lower octane.

however, should you ever deside to switch to a higher octane, you will need to repeat this so that your ECU will compensate for the high octane.

Time consuming, but worth it for all you finacially challenged max owners out there.

the guy from who i bought my car was using regular gas, since i have the car i use the supreme gas and my gas mileage are CRAPPYY. is it because my ECU need to be set it to the supreme gas.
Old Oct 20, 2003 | 04:40 PM
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Originally Posted by djbrown
the guy from who i bought my car was using regular gas, since i have the car i use the supreme gas and my gas mileage are CRAPPYY. is it because my ECU need to be set it to the supreme gas.
no, its probably because your knock sensor is dead
Old Oct 20, 2003 | 04:41 PM
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LastBoyScout's Avatar
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Originally Posted by polishpunk68
no, its probably because your knock sensor is dead
Tru dat.....

Try resetting.....if that doesnt work, get a voltimeter and check to see if the resistance you get from the KS is around 550v . If it is lower, or way off to the high side, or you can smack/bang/tap it and get a different reading then it is bad.
Old Oct 20, 2003 | 04:57 PM
  #5  
DoGGy
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1st owner of my car used 89. im now using 91. do i need to reset ECU?
Old Oct 20, 2003 | 05:06 PM
  #6  
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93 octane rocks!!
Old Oct 20, 2003 | 05:40 PM
  #7  
ivelweyz
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Originally Posted by LastBoyScout
Tru dat.....

Try resetting.....if that doesnt work, get a voltimeter and check to see if the resistance you get from the KS is around 550v . If it is lower, or way off to the high side, or you can smack/bang/tap it and get a different reading then it is bad.

Another noob starting a pointless thread. The ECU in our cars adjusts all the time so doing what the mechanic said is pointless. Even if he is right the ECU is reset while the codes are reset. Also a VOLTIMETER does not exist, and a KS will not give you 550v in a 12v system, unless there are some crazy ztep up transformers we have in there. It's 550k ohms, and even a bad KS can give you the correct reading(500k-620k ohms)
Old Oct 21, 2003 | 09:37 AM
  #8  
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Originally Posted by ivelweyz
...Also a VOLTIMETER does not exist...
a voltimeter and a multimeter are the same things......
I just use my dad's old one, which reads Voltimeter....


Any-who

My KS all read around 550k.....sorry to mis-quote v
....it is ohms....
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