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SR20DET Slave
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892 Posts
Discussion Starter · #1 ·
Sup boys...Ive ran out of things to check so i figured i'd run it by you all...At the start of the winter my gas mileage was about 300 per tank...At about the second week of December it dropped to 230 per tank(at best)...I've done a FULL tune up in november(Wells cap + rotor, Bosch wires, NGK non platinums, 300zx fuel filter, Universal O2 sensor and all new filters)...After a week of the extra pollution i pulled out the plugs and they looked fine...I check my computer to see what codes it shows and its showing O2 sensor...OK...I read about regrounding the MAF(it says could give a bad O2 reading) so i went about doing it...Drive the car a week and no difference...First week of January all of a sudden 303 from a tank...But next tank 230...Mother nature decides to freeze out the entire northeast for the next month and a half so theres not much i can do...Friday i check the puter again and its still showing O2 so i buy the right O2 sensor(bosch)...It did nothing...I havnt checked the puter since the newest O2 sensor so i dont know if the puters still having a problem with it but it didnt help...Am i missing something or could it be the Oxygenated fuel...I find it hard to believe that winter fuel would hurt gas mileage by 30%...The car is running good although i cant get the idle to go above 700 RPM...When i adjusted the screw before(while getting 300)it worked fine...But since then i turn the screw and nothing happens(Yes im adjusting the idle properly...Like i said worked the first 2 times i did it)Anybody elses car Smog up the earth when they use the oxygen fuel?
 

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SR20DET Slave
Joined
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892 Posts
Discussion Starter · #2 ·
I forgot to mention i removed and cleaned the T.B. when i did the tune up...I've pretty much done eveything SE-R.Net has said to do
 

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Professor Dingbat
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5,543 Posts
You can pretty much expect yout fuel mileage to drop around 30% when it gets cold.

What exactly was the O2 sensor code? Was it O2 sensor too lean?
 

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SR20DET Slave
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892 Posts
Discussion Starter · #4 ·
I'm going by the self diaghnostics on the computer...3 fast and 3 slow is O2
 

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Registered
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234 Posts
hey man your sucky mileage is because 2 things. Number 1 is your AICV (the idle screw thing) is clogged up.. take it off and clean it out. Number 2 WINTER.
 

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newbie
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8,148 Posts
I believe that the winter mix sucks big time. I have watched my fuel go to hell winter after winter just to get worst. I think when they stop oxygenating the fuel in May our mileage always go up. I changed everything, O2's cleaned MAF, T/B, you name it and had a oil analysis done and there was no fuel in my oil so I was not running rich. It is the mixture I believe. Also, I find that many different brands seem to burn faster than others. Example, I fill up with Shell Gasoline, I am lucky to get 220 miles out a tank. I fill up with Exxon, around town around 270. Not bad.
 
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