[MSCW list] Hi Mileage RX-7 gas mileage

Bill mscw
Wed Jun 11 15:48:03 CEST 2008

Quoting rem4020 at aol.com, 06/10/2008:

> What is the conventional wisdom on the gasoline mileage to be expected
> from a 1985 RX-7 with 140,000 miles on it?? My mileage is ~12 mpg and
> I am wondering, given its a small car, whether is some one thing that
> I should look for to fix to raise the mileage to a reasonable level.?
> I am assessing what to do with it in the age of $4 gasoline.?

Gasoline is still cheaper than bottled water. :)

That mileage seems low. Unless you are doing nothing but stop-and-go  
driving, you should be getting higher. It's been a while since I've  
daily-driven an FB (though I will again), but I seem to recall  
averaging 18 MPG in mixed driving. I think I still have the logs on my  
bookshelf. I'll look this evening.

With 140,000 miles on that engine, it's just entering it's prime.  
There are some problems that develop that can kill your mileage. Does  
everything work and does the car drive like it should?

Have the catalytic converters ever been changed? If they are original,  
the first one has certainly disintegrated and blocked the second one.  
Both should be rodded-out and completely emptied, including the metal  
mesh that holds the catalyst in place.

The third (main) catalytic converter will probably be OK if the first  
two were there. If they were empty, then the third cat may now be  
plugged. If it is and you live in an area without tailpipe tests, you  
can rod that one out too. If you have to pass emissions, replacement  
main cats can be had from Mazda specialists for about $250.  

It's also useful to make sure that all the vacuum lines are in-place  
and that all the mechanisms on the carburetor are working correctly.  
If the car starts OK and runs well, it may be fine, but since the carb  
controls the amount of fuel you use, it's the prime suspect in  
excessive consumption. A stuck choke or float can raise consumption  

Finally, has the maintenance been kept-up? Fresh plugs, wires, cap,  
rotor, and air filter can make a surprising difference if they haven't  
been changed in a while.

Good luck!
  - Bill
    SRX7 #77 & #79               Go Racing NOW!
    Forest Hill, MD            http://SpecRX7.com/

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