TLTrance

I have a 2005 5AT TL with around 98,500 miles. Over the last 6-9 months I've noticed a reduction in mileage that I get on a full tank of gas (before the light comes on). I used to get around 280-300 with a mixture of city/highway driving, and now I get 200-225. The ratio of city/highway driving is perhaps increased 15% -- nothing too dramatic.

What are the most likely culprits for this reduced gas mileage?

I've been told that since I'm so close to 105K miles, the most likely thing to look forward to is the adjustment of the valves, replace timing belt, replace spark plugs, etc. The dealer is pretty much suggesting that this will "fix my mileage" problems. How much of this do you guys think this is true? I suppose this might be true to a certain extent, but how much?

I got my ATF swapped out 3x3 back early this year (dealer did this). I also changed the cabin and air filter myself. Other than that, I've only gotten an oil change since then (5w-20). I don't think any of these things could've negatively impacted my mileage as much as I'm seeing.

What other things can/should I look at? Fuel injectors? Something else?

VQPower37

try to run some seafoam through it before you get ur plugs changed and such. this should also help with mileage as it gets some of the gunk out of ur motor that is causing it to run less efficient

jr27

yup exactly what i was gonna suggest. sea foam. my 05 tl has 104k miles on it and i still get an average of 20 - 21 mpg and most of my driving is in the city. and to be honest that is only when i dont get on the pedal. i learned this the hard way. at first i drove the car way hard and i only saw like 16 -17 mpg in the city so i changed my plugs like at 98k and it helped like 1 mpg or so but i was still unsatisfied so i decided to change my driving just a bit and now i still drive fast, but when i accelerate i do it carefully just dont let your rpms go over 2500 and you WILL see a HUGE difference even in the city. when i do get on the freeway i slowly get up to 80 mph and set my cruise control and it still helps my mpg to simply accelerate carefully. i still plan to do the seafoam treatment when i get a chance? try these and you will see a difference.

swoosh

iTrader: (5)

city + highway i get ~360-400 miles to a tank.... (80% highway)

i get 500 miles to a tank when am doing all highway....

OP change ur spark plugs asap....

do a seafoam on ur car using 2 cans....1 in the oil crank case...1/2 in the gas tank (when the light is on)....1/2 at the vac port.....

once ur done with this....change ur oil and spark plugs within 200 miles of doing seafoam.....

truongxlong

How are you getting 360-400 miles per tank? that's amazing i get around 250 to 300 per tank 40 bucks everytime i just got my TL should i check the spark plugs and do the seafoam?

swoosh

iTrader: (5)

https://acurazine.com/forums/3g-tl-2004-2008-93/so-i-got-50mpg-769981/

this is the link to a thread i started a little time back....

MPG also depends if your heavy on the gas....ss mode gives u better mileage since i shift at ~2.2K rpm rather than 3k in the auto mode....

so yeah lots of things....but u should do seafoam + spark plugs change !!!

TLTrance

On 100% highway, when things were up to snuff, the most I got was 450 miles right when the fuel indicator light came on. Thus, its entirely possible to get 500 miles. Of course, I was driving between 60 and 70 the entire time, with no abrupt changes in speed.

Bogdan TL

I have some contradicting info about Seafoam and spark plugs. Check this

https://acurazine.com/forums/3g-tl-problems-fixes-114/drop-mpg-after-timing-belt-package-install-792029/