What can cause my lousy 20mpg recently???

[nilsonov]

The wife has a stick mp5, she gets ~30 combined hwy/city.
I have same but auto, used to get ~25mpg on same route, fine.
Now it went down to 22 2 tanks ago, and 20 on the last tank. Haven't done anything differenly (I think). Where could I start looking for such a big loss of milage?

ps - I checked the brakes, none of the wheels are stuck.

 

[bazooka joe]

any cels? how many miles on the car? plugs, bad o2 sensor

 

[The Short Bus]

Maybe check tire pressure. I know here in MN I've lost almost 7 PSI due to the weather change. Don't know if you've switched to winter gas yet, I always take a big MPG hit due to that in the winter.

 

[Mike R]

Do you have a cold air intake?

I normally drop near 5mpg just because of the temp changes.

I made a hot air intake for the winter, and I can keep my milage up.

 

[P-Funk!]

Check tire inflation, air filter and tune up stuff first.

Then run some injector cleaner through it or better yet - do the seafoam[tm] treatment.

 

[nilsonov]

Car barely has 60k miles on it. Changed plugs about 1k ago (saw now difference when I did). Have a regular stock intake (not sure what's a cold or hot). What are cels? Tires are good. Did fuel injector cleaner about 3k ago. Maybe its time for airfilter.

If it was a bad o2 sensor, wouldn't the engine light go on?

Ps - I've noticed it takes a couple of extra cranks to start up now, even when the engine is warm/hot. Any possible relation to gas milage?

 

[Flash5]

winter gas!!!! i know pa must have switched over to it like 2 weeks ago cause my mileage went from 30s on a combined highway/city cycle to 27-28 mpg, but all city im still getting about 23-25.

 

[slavrenz]

Car barely has 60k miles on it. Changed plugs about 1k ago (saw now difference when I did). Have a regular stock intake (not sure what's a cold or hot). What are cels? Tires are good. Did fuel injector cleaner about 3k ago. Maybe its time for airfilter.

If it was a bad o2 sensor, wouldn't the engine light go on?

Ps - I've noticed it takes a couple of extra cranks to start up now, even when the engine is warm/hot. Any possible relation to gas milage?

CEL = Check Engine Light

For the oxygen sensor, they wear out over time and get "lazy". They often won't set your cel, but it's usually a good idea to replace the front one every 100k miles.

As far as your specific issue, are the ignition coils and plug wires the original ones that came with your car? Your hard starting leads me to believe that your ignition coils may be on their way out, which could explain your bad gas mileage.

 

[grmna]

Fuel air mixture

I had a misfiring cylinder, indicated by a check engine code.
after inspection found that the corrogated tube downstream of the air filter box was cracked, perhaps with age. Duct tape healed it so I haven't replaced it yet.

 

[translator777]

winter gas!!!!

I'm from Canada where it can reach -45'C and I have never heard of winter gas...what is it?
And what is Hot air intake (did you just move your piping to someplace hotter under your hood???) ?

 

[nilsonov]

CEL = Check Engine Light

For the oxygen sensor, they wear out over time and get "lazy". They often won't set your cel, but it's usually a good idea to replace the front one every 100k miles.

As far as your specific issue, are the ignition coils and plug wires the original ones that came with your car? Your hard starting leads me to believe that your ignition coils may be on their way out, which could explain your bad gas mileage.

This morning's crankings were particularly bad, sounded like it "gaged" on one of the cranks, and it's not any colder than its been for last few weeks!

Ok, so ignition coil you say? Looking at the manual looks like a straight forward job. I'll swap it w/ the wife's car and see if we end up swapping milage. Will report back. Thanks

 

[03zoomzoom]

HA HA HA. That reminds me of a story. My buddy told his gf that she needed winter air in her tires. he needed an excuse to nail his other gf.

I'm from Canada where it can reach -45'C and I have never heard of winter gas...what is it?
And what is Hot air intake (did you just move your piping to someplace hotter under your hood???) ?

 

[flash75]

There is a difference in summer and winter fuel in many areas. These articles have some interesting information on gas formulation.

http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/summer-fuel1.htm
http://www.zhome.com/ZCMnL/PICS/winterGas/winterGas.html
http://www.theoildrum.com/story/2006/9/13/234043/431
http://www.slate.com/id/2098672/
http://www.epa.gov/oms/rfgecon.htm
http://www.theoildrum.com/node/2374

Clifton

 

[translator777]

Ok, so I guess I was already using winter gas without knowing about it...hence the lower gas prices during winter. thanks flash75