17.5 Mpg For My Corolla 96

[carboto]

Hello there! my corolla consumes fuel like mad. it's 17.5mpg, city driving, typically less than 20mph. It's a far cry from the manufacturer rating of 28mpg. What could possibly happen to the car? Any idea? Thanks!

[compressor mad]

your lambda sensors could be on there way out giving false readings

[Steelballz]

get the diagnostics port hooked up to be sure what it is...

although if you see 2 banks of 4 cylinders-that could be the problem.....big V8 LOL ;)

[Twincam.GTi]

It seems highly likely to be Lambda/Oxygen sensor (which on this model is the old '2-Wire' design if memory serves correct); on this age of vehicle there is only one usually mounted just after downpipe and accessable from underneath . - - -

- - -

Is the exhaust tail pipe very sooty?

When car is stationary and engine ideling do the revs appear to 'flutter' up and down a little?

Has car done more than approx 60-70,000 mile?

As this fault happens over a period of time (and thus ECU makes/ trys to make adjustments it usually never throws the MIL light on or generates a code error)

---------------------------------------------------------------------------------------------------

I presume you have already done the simple stuff - new set of plugs and new air filter!

Another item to check (slight outside chance and not so likely) is the rubber tube coming of the MAP sensor (MAP sensor is mounted on bulkhead behing injection system area) - this tube can get blocked with oil vapour and thus make the vehicle overfuel and run rich ; but because it is a gradual fault (just like the Lambda/ O2 sensor ) over a period of time it never usually throws the 'MIL' light on.