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Discussion Starter · #1 ·
Hello, so i have a 04 b5.5 passat 1.8 T,

Im getting like 10-15 mpg city and like 22-24 highway. its really disheartening cause gas prices right now are climbing up.i can pull 15 mpg when i drive really easy and i average 12. what could be the problem? what other things should i do to try and improve it.

things iv done
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Oil change
Switched air filter to K&N
fuel injector cleaner
Good tires/pressure
 

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put your stock air filter back in or at least a new one. Auto or manual? hilly area? CEL? What is your driving style? Be honest.
 

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Did it started happening after you put the K&N? If so you might have to clean your MAF sensor.

Just like VAGguy said, check for any code with VAG-COM. Also post details like how many miles you have, auto/manual, hilly area etc.

I have an 2002 1.8 with 90k on it. 24-25 on city now (40-45 mph zones here in Texas)

4 things i learned from forums which contribute to bad gas mileage.
1) MAF sensor - You can clean this
2) IAT sensor - You can clean this
3) O2 sensor - Decarbonizer things like RXP might clean this. Never tried it.
4) CTS sensor - Cheap to replace
 

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rustedpeace, why did you changed the CTS? because of a CEL ?

I had that changed about 5 yrs back when one of the host was broken. Later VW refunded me the 100$ i paid for this.

Recently i checked the CTS with VAG-COM. Since it got 2 parts and both showed same temperature, i guess it is fine.
 

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My car started having trouble starting, and when it finally did, the smell of gas was overpowering. I checked the CTS and it read that the temp was -265. :lol:
 

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What was the value after you change it?

After about 30 minutes after stopping the car, mine was 63 for both (or 83 i forgot).

I have rare problem with starting when it is hot outside. It would crank for like 10 seconds or so. If i release and try again, it will start immediately. Now running Auto-RX and RXP as a prevention. Dont know if they will make any difference for this starting issue.
 

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For me, no vacuum leaks so far. The reason is i had to change some of those (4 of them to silicon, then 3 others) and made sure that there is nothing else is leaking.

Does any one uses VAG-COM for vacuum leaks? For me, i just replaced all the broken ones / which was ready to die.
 

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Discussion Starter · #11 ·
put your stock air filter back in or at least a new one. Auto or manual? hilly area? CEL? What is your driving style? Be honest.
I figured out my air intake is misssing something, the intake that goes to the front of the car is missing? its an auto and not a hilly area, no CEL. driving style can be kinda hard sometimes, but most of the time i drive real easy with the passat cause of the gas mileage.

Did it started happening after you put the K&N? If so you might have to clean your MAF sensor.

Just like VAGguy said, check for any code with VAG-COM. Also post details like how many miles you have, auto/manual, hilly area etc.

I have an 2002 1.8 with 90k on it. 24-25 on city now (40-45 mph zones here in Texas)

4 things i learned from forums which contribute to bad gas mileage.
1) MAF sensor - You can clean this
2) IAT sensor - You can clean this
3) O2 sensor - Decarbonizer things like RXP might clean this. Never tried it.
4) CTS sensor - Cheap to replace
nah it was happening before the filter, i was hoping the new one would help. ill check out the MAF sensor. i have 46k miles and its not hilly at all. ill try checking out the the list u gave me too

Did you check the vacuum lines, for possible leaks?
nah i still gotta check
 

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IAT sensor would be the easiest one to clean. IIRC just two screws. Buy a bottle of MAF cleaner from Autozone and use it to clean this. Also you can clean the throttle body when you do this. It is very close. If you are clearing throttle body, dont forget to do the throttle body adaption before starting the car (easy method..Keep hood open, turn on key, DONT start, wait 3 mins and you are done).
 

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one allen bolt for the IAT sensor.
 

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Did it started happening after you put the K&N? If so you might have to clean your MAF sensor.

Just like VAGguy said, check for any code with VAG-COM. Also post details like how many miles you have, auto/manual, hilly area etc.

I have an 2002 1.8 with 90k on it. 24-25 on city now (40-45 mph zones here in Texas)

4 things i learned from forums which contribute to bad gas mileage.
1) MAF sensor - You can clean this
2) IAT sensor - You can clean this
3) O2 sensor - Decarbonizer things like RXP might clean this. Never tried it.
4) CTS sensor - Cheap to replace
The Maf cannot be fixed by cleaning, once the oxyde film are damaged it will newer work as new again. Change it!!
The IAT can be cleaned
The O2 sensor, dont waste your time, change it if its broken.

Look, run a log with vagcom and post, log:tps, rpm, maf, iat, o2(af) and you will easy see if something is wrong.

Also throw that k&n in the trashbin. its a waste of money and its terrible for your engine, it also kills the maf!
READ THIS ABOUT K&N FILTERS : http://forums.tdiclub.com/showthread.php?t=290373
 

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Discussion Starter · #16 ·
The Maf cannot be fixed by cleaning, once the oxyde film are damaged it will newer work as new again. Change it!!
The IAT can be cleaned
The O2 sensor, dont waste your time, change it if its broken.

Look, run a log with vagcom and post, log:tps, rpm, maf, iat, o2(af) and you will easy see if something is wrong.

Also throw that k&n in the trashbin. its a waste of money and its terrible for your engine, it also kills the maf!
READ THIS ABOUT K&N FILTERS : http://forums.tdiclub.com/showthread.php?t=290373

ill need to find a friend with a VAGcom to check it out, otherwise i have no idea where any of these sensors are located.
 
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