So I am starting to get bad mpg..

I clean/change air filter, keep tire pressures up to standard, using good brand fuel and still only getting around 20.5-21 mpg on the highway and 16 in city.

I have the 07 xls and about 25000 miles on it. Since I tried everything to improve the MPG; it leads me that the sparks need to get changed?

My MPG was great before 25k but now, just sucks.
________
Alaska Medical Marijuana Dispensary

 

Just curious but how's your XLS running otherwise. Any stalling, hesitation, rough idle, loss of engine power, etc? I only ask because if you're experiencing any of these it may mean the fuel injectors or throttle body need to be cleaned.

 

spark plugs will not affect mileage unless youre misfiring.
and you would know if you were.

mileage drop has much more to do with climate and driving style than anything else.

 

there are no problems as you listed. Everything seems normal except mpg.

I also did use the fuel injector cleaner from chevron.
________
Simca aronde

 

well the weather here in CA is still sunny and warm still but not too hot. My driving still isn't aggressive. I tried to step lightly on the pedal and see if it improves but no help/
________
Motif

 

have you had an oil change lately where they may have put the wrong grade of oil?

I've only seen it once, but after 160k miles (2nd set of plugs), the plug gaps on my Mitsubishi Eclipse had changed while in the engine. When I take my plugs out, always check the gap. Somehow the gaps had decreased substantially. This would produce less spark, not igniting all the fuel...but I'd imagine that would produce some sort of CEL light and code. If you take it to an AutoZone type of place, generally they'll scan your car for codes. There are two types of codes, current and pending. A current code will produce a light on your dash, but a pending code is when the computer recognizes something may not be right, but has not met all requirements to light up the dash (10 drive cycles, 10-15 minutes of out of spec data, etc).

Even on my ranger, in Kansas City, I only drop 2 MPG during the winter time...not as bad as what you are getting. We just took a tip to Illinois, got 27mpg while doing 70mph. My wife will even hit 23mph when babying it around town.

 

nope im still at 5w-20 as always. I still have 3600 miles to go and using mobil1
________
Bmw E39 History

 

so going to autozone would find out the problem? How accurate are their scanners.
________
V Transmission

 

I guess what I meant about having a scanner hooked up...if you don't have a "check engine light" on, then you don't have a current code...but a pending code will not light that up. A pending code would suggest the start of something failing or "not right". They'd also need to have a "CAN" capable scanner available...which I'm sure they would. IF there is a pending code, you can just google it to see more information.

There are scanners out there that read live data that is outputted from the computer...so accuracy would be on the computer. But you'd need to know what those number mean to see if there is anything wrong.

Have you talked to your dealership about this?

 

i am about to after I go to autozone to see whats up and find out anything.
________
Trichome