Hey there -

A little while back a bought a '90 LX Coupe. It's auto with fuel injection, and has done 265,000 miles.

It's in great shape and has always been looked after.

The car is fine, but the gas mileage is HORRIBLE: I mostly do freeway miles, and since I've bought the car I've only averaged 22-24 mpg. My pal's old 3.8 liter Chrysler V6 does better!!

Surely this is wrong? Everyone I talk to says they get at least 30mpg.

I've checked the obvious things: plugs, plug gap, air filter etc.....all fine.

Anyone got any ideas? Is there anything with the main engine management box I should think about? Should I just go to the junk and buy one, and swap it out?

Any help appreciated!!
Thanks
Bruce

 

there are some other things to consider for gas mileage. are you certain you checked your wires, igntion cap and rotor? the rotor can corrode and not work well. wires can also go bad on the inside. it can also be a dirty intake manifold. I would say try removing the top plenum and check/clean it well.

another i would say is the fuel system. dirty injectors can cause bad mileage as well as a clogged fuel filter. try running a bottle of injector cleaner. i use stp and it works great. try running seafoam in the intake manifold as well. great stuff!

do you have an exhaust leak anywhere?

 

Did you check to see if you have a code in the computer? An oxygen sensor could give you bad gas mileage and still run good.

 

Check that the pressure lever to the trans from the throttle is adjusted correctly, you might not be getting lock up at hwy speeds.
To test it....fully warm up the engine and drive along a level road at 25 MPH under light throttle; then floor the gas. The trans should down shift to first gear.
Repeat the same drive at 28 MPH, when you floor the gas the trans will only downshift to second gear.

 

Many thanks everyone - this has given me a lot to think about.

My pal has one of those fault code readers - I'll pluf that up to the computer and see if there's a fault reading.....and check the other stuff too.

I'll keep you posted!

thanks
Bruce