dirkdiggle

iTrader: (1)

I have had my 1992 SC400 for 7 months now. For the months June - September my SC400 was getting a consistant 22-24 mpg(very happy). From the end of september till now I get 17 mpg consistantly. What can cause this sudden horrible mpg????

I check my Gas mpg at every fill up(by doing the easy math). I remember once it started to get cold outside my gas mpg just instantly dropped to 17 mpg even if it is 85% highway. I live in Wisconsin.

Can cold weather cause it to run super rich or something??
I really have been missing the 22mpg and every fill up I tell myself it will be better but it has been 2 months and no improvment.

my driving habits havent changed and I drive 80% highway. My spark pluggs, wires and throttle bodies cleaning has been done 5 months ago.

Any ideas?????

O. L. T.

iTrader: (17)

do you put a set amount of money worth in?

dirkdiggle

iTrader: (1)

1st) I fill the tank 100%
2nd) I drive car till the tank is almost at empty
3rd) I take notice of how many miles I have driven(I reset the trip meter back to zero everytime)
4th) I fill the tank up to 100% again
5th) divide the gallons I just put into tank by how many miles I drove = MPG

Luke_in_SD

dude, I am experiencing the same problem. I used to get like 18-19mpg city high mixed now I'm getting 15 mpg

this sucks

Biggu

iTrader: (12)

if its cold the mpg should go down some

CyBorG

17 isn't that bad for the 1992 engine, remember they are rated 17-19 city/highway. If you do all highway, you may exceed the 19 highway average estimate. But in my experience, I've had an issue like this once, which was related to alignment. I literally went from 18mpg to 13-14 mpg. I could easily tell because I only got 220 miles from a whole tank. So see if you have any tires wearing out unevenly in the inside and outside of the tires.

parnzen

check if its runnin cold. if it is then that could be ur problem

cip

Don't forget in the frosty states they switch us to less 'efficient' gas blend. Winter gas makes a notable difference. Also, make sure when you're using the the climate control click off the A/C if you leave it on AUTO. It will kick on if you're trying to defrost the windshield

Luke_in_SD

I like in San Diego, and temperatures aren't even that cold yet.
I'm gonna try to switch to a lighter oil next change for the winter months

Luke_in_SD

did the alignment yesterday, wasn't too far off from the specified range.
Changed fuel filter, put in good gas chevron + bottle of techron,
added air to the tires, new toyota filter.

I have to get at least 1 mpg gain here

Luke_in_SD

taking the car in to a shop for a diagnostic test later this week.

My friends 92 SC400 just got 375 miles on tank, and he does more street driving