Sudden drop in gas mileage

[ptjoe]

Hi Guys.
My 02 Cruiser just turned 78,000 miles. Had plugs and wires changed at 74000 Car seems to running fine. Starts easy and runs smooth. Car has never burned a drop of oil.
So why is it I've had a significant drop in MPG over the past 2 or 3 months. Mileage has dropped from averaging 19-20 mpg to about 12-13 mpg, even less on some days..
Air filter is new. Tranny oil is clear and shifts great.
Is the old girl worn & tired or just sick???
I'm turning to the experts here on the forum for answers.
Any ideas would be appreaciated..
Thanks
PT Joe

[CREWZIN]

The EGR and 02 sensors have a bit to do with the gas mileage but most of the time both things set off a fault code if they aren't working properly. You didn't mention the air filter, is it clean?

[Hooligan]

Originally Posted by CREWZIN

The EGR and 02 sensors have a bit to do with the gas mileage but most of the time both things set off a fault code if they aren't working properly. You didn't mention the air filter, is it clean?

He mentioned Air Filter is new!

[quicksilverdon]

I track all my mileage the old fashioned way - write down every fill-up.
You don't say where you are, but winter drops MPG by 1-2 for me, and that's not counting the drop in tire pressure.
What did you gap plugs at? Should be 0.040.
Have you changed gas stations/brands?
Keep those tires inflated!
Does your gas have a lot of ethanol in it that it didn't used to?
Throw some injector cleaner in - I hear Lucas is good.

[ptjoe]

Originally Posted by CREWZIN

The EGR and 02 sensors have a bit to do with the gas mileage but most of the time both things set off a fault code if they aren't working properly. You didn't mention the air filter, is it clean?

Air filter is new, Less then 1500 miles.
I was thinking a possible emission problem but as you pointed out, I should have set off a code...Is there a gas filter on this buggy?
What type of MPG should one expect from a Michigan cold start to driving local roads on average less then 3 miles each day?
Thanks
PT Joe

[CREWZIN]

Originally Posted by ptjoe

What type of MPG should one expect from a Michigan cold start to driving local roads on average less then 3 miles each day?
Thanks
PT Joe

Less than 3 miles a day? It doesn't even get a chance to warm up. The 02 sensors don't come into play. The IAC/computer controls are dumping as much fuel into the throttle body as possible to keep the cold intake air and fuel in the proper mixture. Probably the worse scenario possible to try and get good fuel mileage.

[quicksilverdon]

Gas filter is in the gas tank - I don't think that's it.

I'm in NW Joisey - coldest is zero, maybe 10 below - in Michigan in winter, I doubt you get warm in 3 miles.....
I drive 50 miles, takes about 2 miles beforer temp gauge moves in winter.

[cjb15]

Funny coincidence you mention Michigan. I noticed last winter in MI, my PT lost about 3 MPG with the cold weather. I only drove about 10 miles one way. Once it got warmer the numbers went back up.
Now I drive twice as far so I'm interested to see the difference.
But definately check your tire pressure.

[ptjoe]

Originally Posted by CREWZIN

Less than 3 miles a day? It doesn't even get a chance to warm up. The 02 sensors don't come into play. The IAC/computer controls are dumping as much fuel into the throttle body as possible to keep the cold intake air and fuel in the proper mixture. Probably the worse scenario possible to try and get good fuel mileage.

Yea, you're probably right, although I've been driving this way for over two years now and only recently began to have this problem.
As someone here pointed out, I'm wondering if gas/ethenal may be to blame.
I've been getting most of the gas at Sam's Club.
I may try other brands to see the results.
Thanks for all the responses
Joe

[Jered]

my question, did the drop in fuel milage happen before or after you started to replace tune up parts?

Did you go from a better plug to a basic champion, wires oem quality or better or cheapo autolite ones?

How about the gas your using? same brand as before? Not going to go into the whole discussion about ethanol and all that but I get less MPG's with the 10% mix gas as I do with pure petro... Is it drastic? YES IMO, I usually get 3-5 mpg's better with pure gas then the 10% mix.

What changed?