I have an 06 TL 5AT w/ NAVI that has always gotten very respectable mileage (30+ on the highway, 23-25 around town / combo). As recently as Thanksgiving of 07, I was still getting this kind of mileage.

When the winter blend fuels took over, I didn't give much thought to the fact that my mileage went down. But, now, it should be back up - and it isn't!

My car has approximately 56,000 miles on it and has been maintained with oil/filter changes and air filter changes as it should have been. I had a new set of tires put on at about 51,000 and had a full alignment done at the same time. Tire pressure is always kept correct.

A recent trip from CT to ME (two weeks ago, end of May) resulted in HIGHWAY mileage of 25.

I'm looking for COMMON reasons that mileage would have gone south on me: dirty MAF, bad plugs, failing O2 sensor(s), etc. I have gotten *NO* CELs at any time with the car, never have an issue starting the car, and it does not feel significantly different in terms of performance from a brand new one (loaner).

The only issue that I do have currently is that the car pulls slightly to the right, and I'm working with the dealer to try and resolve this (even though their alignment report shows that my alignment is dead on, even after two months). I realize that this could be at least part of the issue if I'm dealing with a tire that has a bad belt and is causing the pull.

If the AcuraZine members have some suggestions for me of things to check, please pass them along!

Thanks!

 

What was your average speed? What were the weather conditions? Are you using synthetic motor oil? Check your air filter? What brand kind of gas are you using? The no-name stations can have 'old gas' and there still might be some ethanol laced stuff in their tanks.

Also, these suspensions can tend to have alignment issues and sometimes a camber adjustment kit installed in the rear is required to make it dead on.
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Your tires also have an effect on MPG- what type of new tires? If they are summer performance tires, that would likely reduce MPG slightly from the stock tires. Also, the tire pull would reduce MPG.

Get the tire issues resolved first, then check the MPG again. G/L!

 

Ok... Some additional info to answer some questions:

- The new tires are Yokohama Advan's, and they're an all-season. They're very similar to the Michelin OEMs that they replaced.

- There was NO CHANGE in the mileage from old tires to new.

- According to the Trip Computer, my average speed was likely around 55-60. According to the driving I was doing, I would estimate most of it to have been about 10 MPH higher.

- The gas I use is 10% ethanol, different brands from a couple of local stations. And, it's the same gas that I've been using right along.

- I do not use synthetic oil (never have).

- Air cleaner / filter is brand new (less than 1,000 miles, but was changed AFTER the long-haul trip).

The car is going back to the dealer on Friday to see if the computer shows anything (degraded O2 sensor or something).

 

Ha, before 01tl04 got here, but seafoam it, over time carbon build up and clogged fuel injectors take their toll on the engine. Seafoam will clean it all out and you will notice more power and MPG. I also suggest that you raise the PSI in your tires to around 35, that may help with the MPG. As far as the pulling, swap the tires left to right (if you can, non-directional) and see if it pulls to the left. if so, bad tire, if not and still to the right, its a suspension problem. Make sure the alingment machine they use is a Hunter one, those are one of the best out there.

 

I respect the fact that the injectors could be performing less than perfect. However...

My mileage dipped when the winter blend fuels were brought out, and it has STAYED THERE. This has not been a gradual decline in mileage.

What really irks me is that my car was under warranty until about February. The mileage dipped last December. I didn't think anything of it because of the fuel blend change. If it turns out to be something wrong with the car, I now have to pay for it because I'm out of warranty and don't have a record of the dealer looking into it before the mileage passed 50k.

I don't MIND paying a repair bill that's reasonable - I'm just not interested in paying $200 for this, $300 for that, and having none of it be anything more than "well, this MIGHT help".

The tires ARE directional, but you can swap them long enough for a short 40MPH or less jaunt to see if the pulling changes. I just don't have the time to do it for a couple of days, and the car is scheduled to go in to the dealer tonight for the re-set of the steering wheel (it was left off-center when the did the alignment) and the computer diag check ($45 - totally worth it if they find there's a functional issue).

 

-It can be a full list of item which can cause your MPG to be lower. I recently took a short trip to Pennsilvania from NYC. I was driving 60mph all the way there and here what i was getting. I seafoam my car about 2 months ago, changed my spark plugs around 1 week ago. I'm running Mobil 1 Full syn Oil. And i only use 93octane Fuel. I also have a Fujita cold Air intake.

 

Clean the maf, driving 10 mph faster could be a major problem and why a 10% ethanol blend. That will also lower mpg. Good luck

 

I have no choice on the 10% blend. Everything in CT is 10% now - used to be 7%. Thanks, US Govt!