Lately I noticed my gas mileage decrease dramatically on my 07 TL Nav. 200 miles in one tank! grandma driving. The car just feels sluggish like it lost its power. I replaced the oil and sparkplugs with NKG to see if it will fix the problem but no luck. I seafoam the crap out of it and nothing! Also I've been getting a tighten gas cap light on alot. I need some help Acurazine! I have about 70K miles on the car.

 

heatsoak.

 

heat soak wont reduce the gas mileage down to 200miles/tank...

OP what are your driving habits ? if you forgot to tighten the gas cap then you gotta let the ECU cycle which is 150 odd miles....or you can reset the ECU and see how it goes....

Also any mods done ?

 

I actually been driving under 2500rpms to see if it was my driving habits but I'm still getting 200miles a tank. I tighten the gas cap the ecu resets, light goes away. Then randomly a week later it happends again I retighten and goes away but it comes back.

 

City / Highway ?
Auto/Manual/Sports ?
miles on the car ?
weather conditions where you are ?
how do you fill up ? stop at the first click ? round off to the next dollar ? add another gallon ?

Please answer those questions and also you said:

"a week later it happends again I retighten and goes away but it comes back"

does it mean you were not tightening it properly ? coz everytime the light came on you retightened and the light went off....are you topping offff wayyyy toooo muchhhh ?

 

City driving mostly, auto at5, 95-102F.73K miles, stop at first click when filling up 93 octane, it does not come on when I fill up, I might have like half a tank and it comes on, I stop turn off the car and remove the fuel cap and tighten again after 3 clicks. Drive for 30 minutes light goes off and couple days later comes back on.

 

When I first got the car it was getting 250 miles city in one tank and 320 miles highway one tank. Car was responsive. Now just feels like it struggles to go. Poor gas milage and gas cap light on all the time? Could it be something with the emissions? I don't have an engine light on.

 

city driving 250 miles /tank sounds about reasonable....i used to get ~250-280 miles city and get 340-370 miles city+highway and highway only gives me 450-500 miles.....

i think either the cap is coming loose (something with the cap mechanism or the seal or something) or the sensor is going bad....

i would take it to the dealer either way. I know that gas is effervescent and a loose cap, the gas will evaporate (dont know by how much) but that could be a reason....

do you see any spill drop in the fuel cap area ?

again am thinking out loud, dont quote me....if i were you i would call and ask the service manager or prolly take it in....

 

i had the gas cap warning come on frequently too. took it to the acura dealership, and they told me it was because of a faulty purge valve. planning to have it replaced on friday.

 

I'll check my warranty. Cfujikawa were you getting bad gas milage before you had the purge valve replaced?

 

no, i didn't notice anything odd with the gas milage. i typically get 250-270mi city before the light turns on.

 

Solved the problem! My gas milage dramatically increased and power is back! It was something super stupid. There is a plastic cover at the end of the air intake between the drivers headlight and battery. The cover fell off on the intake pipe, blocking the air suction! I removed it, now I'm getting 25mpg avg!

 

that part is called the intake resonator (correct me if am wrong)....and most people who have stock intake have that part removed....

well am glad you fixed your problem