This is not due strictly to summer/winter fuel, I'm seeing this decrease on top of that.

I've had my automatic 2005 TL for over 4 years, it only has 41k miles. For about the first 3 years I was getting 31-32 MPG highway in the summer and 29-30 MPG highway in the winter.

Over the past year I've noticed my MPG decrease down to about 27-28 MPG highway in the summer, and 25-26 MPG highway in the winter. Subtle but definitely noticeable.

My old tires weren't holding air well so I thought perhaps that was the problem, however I just put new tires on and the MPG has not improved. I get all the scheduled maintenance done when I'm supposed to.

I guess my next step will be a fuel additive to try to clean out the system. Just wondering if anyone has any other suggestions if that doesn't work. Thanks!

 

1. Clean / Replace your Air Intake Filter.

2. Make sure your riding on 37-40 psi in the tires.

3. Seafoam / B-12.

 

I always nitro'ed my tires at 35 PSI, and it automatically raise to 38 to 40 depending on outside temp.

BTW, Seafoam / B-12? What's that?

 

Well definitely check your air intake filter and replace it if necessary.. your car will eat gas if it's gasping for air..

You'll want to run seafoam / techroline / Berryman's B-12 fuel system cleaner on a full tank. It'll clean out your fuel system / fuel injectors. You may also want to seafoam the intake.. Google search "DIY seafoam acurazine".. the acurazine search is going a bit haywire unless you seach for posts instead of threads.

 

What oil weight are you using? 5W20 is recommended but if your using 5W30 it may affect the MPG.

 

and make sure ur not lead footing the car that usually has an effect on it

 

Different tires can effect your MPG because of the tire's compounds used for the rubber. Sticky tires will adversely affect your MPG because they will have higher rolling resistance. In your case, you're taking a 10% hit in MPG now with the new tires.

When you quote your MPG it's also helpful to quote your average MPH because that may tell more of a story too. I changed tires on my Wife's Pilot and we're getting 2 less MPG than the stock tires did so I know tires make a difference.

 

I believe LaCostaRacer is correct, its the tires. I changed my tires a few months back and now i am averaging 27 MPG on Highway. I used to get around 29-31 before new tires.

My old tires were riding on the tread bar, so i would think less rubber equal less weight. I dont mind the lower MPG, cause the OEM tires sucks..felt nervous when it rains and snow. The new ties I feel more confident even in a snow/ice plaster highway.

 

thermostat?

 

tire pressure, and seafoam the gas and intake manifold vac port at the TB
Simple DIY that will make car run like new

Low mileage cars are often driven on short trips so the crud never gets hot and blown out, needs to be done on every car now and then
Air filter check for sure
May be time for an EGR port cleaning

What tires are you on now? the rubber left on tire is not the mileage issue- its the rubber compound and its stickiness to the road-
whats the treadwear rating on the tires now?

 

2. NO WAY. riding on more PSI than what is recommended by manufacturer is just plain STOOOOOOOOPID

 

High PSI would make you feel every thing from the surface of the road, and that's why most manufacturer don't want you to... Especially before they've incorporated Drive-by-Wire technology.

That's the reason people bxtching about 3G, especially TL-S...

 

Oh yeah.. and change your oil every 3k miles no matter what.

40 psi is well within the appropriate range. Keeping the tires between 37-40 psi ensures that the tires will have minimal footprint decreasing the vehicles rolling resistance, which theoretically increases fuel efficiency. The mfg suggested tire pressure is a solid middle of the road all conditions pressure.. remember it's a recommended pressure for normal driving. My suggestion was to ensure the tire never looses pressure to adversely effect fuel economy. It is true that inflating the tire to this range will incur more road noise.

And for those driving like they're on the autobahn or if you drive your car like you're autocrossing.. you should definitely inflate your tires to at least 37 psi. Underinflated tires will stress the sidewall structure and will eventually compromise the tire stability.. end of story.

 

many aftermarket tires- especially performance type- require more air than the door sticker says for the STOCK tires
That factory number is a compromise between comfort- noise- and mileage
Stock tires are often super hard compound as well

My General Exclaims- per email to tech support- says 40 psi
An easy method is 80% of max cold pressure should be about right

No need to change oil every 3000 miles if you use real automobile oil,,, not crisco!

5000-7500 miles is fine- modern oil is designed to run that far, and a good filter allows capture of particulate matter during that time

 

I forgot to make my statement in red: Oh yeah.. and change your oil every 3k miles no matter what.

I guess I need to work on me e-sarcasm.

 

I realized that right after I posted-
doh! he meant that in red --but others new to the forum may not understand and actually believe they need to do crazy things~~

 

lol and you guys wonder why your tires wear out quickly....

everyone thinks they are smarter than the engineers at acura or the tire manufaturer....lol Ford tried that with Firestone and they got screwed......

 

seafoam FTW and a tip: while sucking the liquid into your vacuum to the intake manifold DONT let it stall !!! mine shot liquid back up at me and the smoke that came out of the manifold to my cai made me a bit scared. But it worked fine.

Point is car feels smoother and im getting +3 MPG's baby back up to 24 city

 

The proper tire pressure of an '05 automatic TL is 32psi all around. My "other" TL is an '05 automatic and using that pressure, it gets over 25 MPG in western Prince William County, VA (county-suburban driving) and over 32 MPG on interstate highway when traveling on vacation road trips.

Make sure you're using a quality fuel and use a quality fuel system cleaner (not fuel injector cleaner) every 10,000 miles (Cheron Techron is a good one). Replace your engine air filter element once a year or every 15,000 miles. Watch your right foot (doesn't mean you have to drive like you're afraid of the thing). And instead of using the on-board mileage check, try a few times using the old tried-and-true method for a really accurate mileage check.

 

From the Acura TL Manual:




Me love you long time - I'm an engineer.. and the one thing that you learn is to think for yourself and to think fast in critical situations. Next time someone tells you something or recommends something to you.. ask why.. and then process the consequences and ask yourself does it make sense.

01tl4tl had the best advice.. inflate the tires to 80% of their maximum rating. So if your tires say 40 psi max then keep them at 32.. I assume most of us are running soft Z-rated tires with tread ratings around 300. My max tire psi is 50. You're more likely to end up in a low tire pressure situation running 32 than above 35. Frequent low pressure situations will eventually kill your tires before the tread has a chance to wear down. Most people I know don't even periodically check their tire pressure and just do a visual inspection which is asinine with low profile tires. I check my tires every week and after cold fronts. I suggest to people to inflate their tires to high speed ratings because most people aren't vigilant in doing periodic tire pressure readings. If you check your tires every other day and keep them at 32.. bravo.

 

note those pressure numbers on the door sticker or book are for the STOCK crap tires- and are a compromise,, not the best pressure for different conditions

to the person on Nitrogen- they should not be changing pressure like that!!!- the whole point of nit. is that is not expanded by temp!
We use in in the race car tires for that reason- pressure stays the same from 100 degrees to 200-- external tire temp

Check the tire sidewall info for the max cold at max weight
You will see the car is about 80% of the max allowed weight on each tire- so its operating pressure is about 20% lower than the max weight pressure listed
If the tire says 50 max try 38-40
Load the car up with people and luggage and higher pressure is required for sidewall stiffness

 

Has your state switched to ethanol blends in your gasoline? That will kill your mileage. I noticed an instant 10% drop when they did that here in Oregon (E-10)

 

Low pressure is really bad for the tires

Fords problem on the exploder was they used lower pressure than Firestone said to,- in order to balance the vehicle and make it less prone to rollover--
The result was increased internal tire temp and belt seperation failure
Some of the tires were defect in making - others were the lower pressure issue- and iirc they ran 32
those things are just rebadged Broncos--- and they always ended up on the roof~

Want to get a good reading? invest 20 bucks in an infrared thermometer and check the tires in 3 places across the tread after a hot run of cornering
Perfect is same temp across- good is within 20 degrees and location of increased temp will indicate if you have a toe issue- camber or pressure

At the track we paint a white stripe on the sidewall- go out on track and if the stripe is worn off an inch up the side we know it needs way more air!!!

 

I know everyone thinks winter gas causes mileage prob- but its the summer gas that has more crud added to it to combat pollution~

E10 is the national standard with the last few states finally coming into compliance
It replaces MTBE added gas- which was found to be NOT friendly to the earth-
found in groundwater-hazmat!

 

- do you have a choice? Sad to hear.. hopefully they'll stop trying to push that crap at the pump.

 

No choice and Oregon won't let you pump your own gas, so usually you end up with some illiterate or a questionably legal person pumping it who puts regular when you specifically ask for Premium

Just across the border in Washington, they have normal untainted gasoline and if I fill up there, I get 10% better gas mileage consistently in spite of their 5 mph higher speed limits

 

Yep...

I just wish the gov would switch to something that makes more sense. push bio-diesel. push electric cars. but why strain our resources for E10 and cut food surplus that helps others.

I'm always going to want the roar of a v6 or v8 but I'd commute with an electric car.. higher drivetrain efficiency.. zero vehicle emissions.. wish I could afford the tesla..

 

That's rough and complete b.s. - Well if they ever put crap in your tank hopefully they'll be paying for it.

 

Yeah, that's a crazy stupid law you have there in Oregon about not being able to pump your own fuel. What were your employee's (read that as representatives) thinking when they managed to push that one threw??

The idea that someone can dictate to me something like that would be enough to keep me from moving/living in a state like that.

Government. Jefferson was right. You have to rise up and kill some of them every 20 years to keep them answerable to their bosses (us).

 

Thanks for all the tips guys. I just read all the replies quickly as I haven't had a lot of time since I've posted this. I'm currently out of town but I'll be trying Seafoam within the next few days. I'll post the results.

As far as tires, I had the stock tires for 41k miles @ Acura recommended PSI. Now I'm on Goodyear Eagle GT's based on recommendations on this forum.

 

All I am going to say is lol.