MPG dropped 5mpg after tires and wheel alignment?

[USMC5811]

I have a 2007 M35X and two weeks ago i replaced my toyo proxes with bridgestone 970's and i also had them perform a wheel alignment. Well before I got all this done I was averaging between 18.8-20.2MPG. I religiously calculate my MPG every time i fill my tank and i even cross reference it with calculating miles driven divided by miles added. Well after the new tires and the wheel alignment I am now averaging somewhere in the 14MPG range. I drive 26 miles to and from work and half of it is highway and half of it is in Philadephia.

Another issue that may be causing the sudden drop in MPG is this grinding noise I hear sometimes when turning hard right from a stop. When I turn hard right from a stop i can hear and feel some sort of grinding from the passenger side i think. At first i thought it could've been a bad wheel hub and i replaced the wheel hub a few months ago but still heard the noise sometimes. Then i thought it could've been the tires so i replaced the tires and I still hear the noise sometimes, but not as often.

Does anyone know what could be causing this grinding noise and could it be related to my sudden decrease in MPG?

Could the tires or even the wheel alignment have caused my sudden decrease in MPG?

Only mod done to my car is a Z-tube and a K&N filter. I had the 5/16 plenum spacer, but rtook it off this weekend to see if that would help my MPG.

Thanks in advance for everyones help, this website has been extremely useful for me so far!

[svard75]

k&n filter could have released some of the oil into the intake and its collected on the MAF sensor which could in effect cause the same effect as a dirty filter. The grinding noise could still be a bad bearing, however when it sometimes appears like it's one side it could actually be the other. I doubt the wheel bearing would cause that drastic of a MPG change unless it's in really bad shape and it's actually going to separate soon.

[USMC5811]

Also I will be selling my 5/16" Copper Iso Thermal plenum spacer. This is the one that comes with the iso-thermal gasket and the copper throttle body attachment. I have all the parts and even the directions. Also the iso thermal gasket and the copper throttle body attachment are brand new since i never got around to installing them. I purchased them about a year ago for $310 and they're the real deal. I'll take the best reasonable offer for the kit, but i'll only ship to the lower 48 states. PM me if you're interested. Ill be in punta cana from tomorrow until the 16th so don't worry if i don't respond right away.

[szh]

k&n filter could have released some of the oil into the intake and its collected on the MAF sensor which could in effect cause the same effect as a dirty filter.

Yeah. I try to warn people about this all the time ... even if the filter feels "dry" to people (minimal oil), it is still going to release some micro-droplets of oil into the air-stream. This oil deposits and burns onto the hot-wire MAF sensor that our cars use, and eventually causes problems. If there is too much oil, it just goes sooner rather than later.

Then the engine misbehaves ...

Z

[USMC5811]

Is it safe for me to clean my MAF? I will get rid of the K&N tonight and go back to a normal filter. Thank you for the input!

[jiggersplat]

i had a wheel bearing go bad... i could just barely hear it when i would drive next to a curb or a jersey wall. just a very quiet clicking... knocked my mileage down by about 5-6mpg.

[svard75]

Yes you can clean your MAF with isprophyl alcohol and a soft cloth. Spray the maf, let sit for 30 min then wipe exterior. Make sure it's not hot when doing this.

To test for wheel bearing lift each wheel while the car is in N (block the wheels so it doesn't move) and listen/feel for grinding.

[The00Dustin]

Did you spin the wheel before you replaced the wheel bearing? I had a bad wheel bearing and everyone thought it was one (mechanic included), but it turned out to be the other. If the mechanic had just replaced it based on where we all thought the sound was coming from, the sound would have continued just like yours did, because it was actually the other one. That would be most likely to explain the grinding noise whether it explains the mpg drop or not. Wheel bearing could reduce MPG, so does winter gas, new tires can, too. Not sure on the K&N attacking MAF, several people swear they are evil and have oil orgasms in M's and several people swear it's impossible for oil particles to flow all the way to the MAF with normal aspiration in any vehicle.

[mazz]

buddy it could be as simple as air pressure in the tires if you were running 40 and now 30 lb of pressure remember temps drop in November and December my tires lose pressure every year

[szh]

Is it safe for me to clean my MAF? I will get rid of the K&N tonight and go back to a normal filter. Thank you for the input!

I believe it can be carefully cleaned when cold, but I have not done this myself, so please take my words with a grain of salt!

If you do go back to the stock air filter, just replace it very 10k to 12k to 15k miles (max) and it will do just fine. Unless you live in very dusty conditions, those intervals should be quite sufficient and it is inexpensive and easy to do it yourself anyway.

Z

[EdBwoy]

If you haven't figured it out yet, I've got a guess for your grinding. Is there a possibility that the brakes on that side are frozen? That could make some noise as you just start to move again.
Out of curiosity, what happens when you turn a hard left from a stop?

[USMC5811]

Sorry for the delayed response, but here's what I gather so far...

Did you spin the wheel before you replaced the wheel bearing?

Prior to replacing the passenger's side bearing I did spin in and test to make sure it was bad and it was in fact bad. It was also very loud when i would drive next to a jersey barrier on that side with my windows down so i knew it was that side. However, after that i never checked the driver's side so I will definitely do that.

buddy it could be as simple as air pressure in the <a class="vglnk" title="Link added by VigLink" target="_blank" href="http://www.walmart.com/cp/1077064?povid ... ires_Tires" rel="nofollow"><span>tires</span></a> if you were running 40 and now 30 lb of pressure remember temps drop in November and December my <a class="vglnk" title="Link added by VigLink" target="_blank" href="http://www.walmart.com/cp/1077064?povid ... ires_Tires" rel="nofollow"><span>tires</span></a> lose pressure every year

Yup I understand that and I check my PSI every day, especially in the winter for that reason. I used to run about 39psi in my tires but right now im running 34. Not sure if that would make that much of a difference but I'm open to all suggestions and i appreciate your feedback!

If you haven't figured it out yet, I've got a guess for your grinding. Is there a possibility that the brakes on that side are frozen? That could make some noise as you just start to move again.
Out of curiosity, what happens when you turn a hard left from a stop?

I know that sometimes my brakes will stick when it is raining and cold out and i can tell because after coming to a complete stop for a short period of time i can hear the pads break free from the rotors when i release the pedal. When i turn hard left from a stop everything is perfectly normal. The noise, which i guess could be considered a groaning type of noise, can only be heard sometimes when turning hard right and accelerating from a stop and it usually happens half way through the turn and lasts about a full second.

once again thank you for all of the input everyone, I know I'll get this figured out soon with everyones help.

[Larz]

You lot mentioned cleaning the MAF and I have done that. I can't give you a good reason for having done it, cuz most experts I have talked to since have told me NOT to mess with the MAF unless it is causing trouble with engine performance. I did mine simply coz I'm anal that way. I have a 2009 with the HR engine so I have two intakes, two MAFs, and two air filters. There is a great video about this procedure below, and here are some tips:

1) engine cannot be running and MUST be cold (say after it sits overnight).
2) you can NOT touch it with hands, gloves, towels, etc. It is so sensitive that any contact with another object can ruin it.
3) you MUST use MAF cleaner - NOT carb cleaner, Throttle cleaner, etc. Auto shops carry it. I used CRC MAF cleaner spray.
4) It MUST be completely dry BEFORE you re-install. Let it air dry until you're sure it's dry, then wait some more to be safe.

CLEANING MAF SAFELY:
http://youtu.be/_TO7ZC5N-aA

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I made a DIY called "CLEANING THE MAF" that contains this video and also describes a problem I caused when cleaning mine - and the solution to that problem.

[EniGmA1987]

Yup I understand that and I check my PSI every day, especially in the winter for that reason. I used to run about 39psi in my tires but right now im running 34. Not sure if that would make that much of a difference but I'm open to all suggestions and i appreciate your feedback!

It can make a big difference. For long trips you pretty much always want to add a few PSI to your tires to maximize MPG. Dropping from 39 to 34 PSI could accord for as much as 2-3MPG loss.