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Old 03-27-2013, 02:58 PM   #1
dooor
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Oxy sensor & mileage loss

Between 50,000 & 70,000 miles my gas mileage for highway dropped from 36-37 to 30-31. New plugs, intake track cleaner, gas tank cleaner, with the usual oil and fuel filter changes, got it up to 32-33 mpg. The car is a PZEV2007 2.0 mtx stock. I want to restore the mileage before doing mods. All I can think of is the oxygen sensors- car has 3. That will cost some $$.

The injectors make noise. They click. Is that normal? Tire pressure is adjusted monthly. Air cleaner is the "lifetime" one & the vacuum gauge is in the green. How is that thing tested?

Do the oxy sensors degrade without throwing codes? Should I suspect them?
Please post your ideas and suggestions for restoring fuel mileage. Thanks

Is anyone interested in starting a gas mileage thread for reporting gas mileage changes from doing mods?


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Old 03-27-2013, 03:11 PM   #2
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As the filter gets more clogged the vac on the engine side of the filter gets higher this moved the vac gauge out of the green , In my opinion they still need cleaning /changed about every 50,000 miles , there dirty
Yes the Inj can get noisy , its normal

In most cases the o2 causes a CSL if they go bad , its only the 1st one that can cause poor MPG , see if some one local has a xcal3 and you can log and see the condition of the o2 by loging it , I will be glad to look it over for you

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Old 03-28-2013, 05:18 PM   #3
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Parts for a DIY stealth CAI are being collected. I forgot to post that cleaning the MAF sensor got the biggest mpg improvement. What is a CSL please. I looked at the site abbreviation/tech. lists & didn't see it.
Thanks for the offer.
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Old 03-28-2013, 07:49 PM   #4
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Sorry ment CEL , with MAF dirty this changes the fueling but not to where the o2/ecu cannot correct it so that shouldnt of helped

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Old 03-30-2013, 06:02 AM   #5
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A failing or failed upstream o2 sensor will cause an mpg drop.My upstream sensor just failed and threw a code and I saw a significant loss in mileage.
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Old 03-30-2013, 10:13 PM   #6
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Rock auto parts lists an oxy sensor #DY1028, upstream location. For a PZEV is that the correct part?
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