Bad gas mileage

[seadoon1]

I had a 90 xfi metro 3 cyl that got 70mpg on hwy, 35 city then wrecked it.

Now I have a 97 lsi metro 3 cyl and it only gets 40mpg hwy, and 28mpg city!

What's wrong here?

The new one has 195 psi compression all 3 cyl. Checked timing at 5 btdc, but not sure if that check connector shorting was working right. Someone here said to unplug map sensor to make sure the computer is not advancing the timing while setting.
It runs good except a very slight surging on constatn acceleration.

Any Idea's?

[Woodie83]

Your biggest problem is government intervention in private commerce. Starting in 96, they mandated a whole crapload of safety features that transformed the Metro from a 1570 pound car (less for the XFI) to an 1800 pound car. It's now too heavy to be a good match with the 3 cylinder engine. I had identical 3 and 4 cylinder mk4 Metros and there was only 3 mpg difference between them because the 3 just had to work too hard. I think you should be getting 35 city and 45 highway, but everyone drives differently. Pump your tires up to 35 psi and advance your ignition timing to the brink of ping, usually around 10 degrees, that will help. You will probably have to retard it back to 5 to pass emissions.

[seadoon1]

Except that I used to drive my old one with 2 adults and 2 kids for a total of 475 lbs and 4 pairs of ski's, boots, and gear, and still get 60 mpg!

So something is amiss/

[metro_roy]

How many miles on the oxygen sensor? An old sensor could be giving erroneous readings causing too rich a fuel mix.

[Hudson]

Originally Posted by seadoon1

I had a 90 xfi metro 3 cyl that got 70mpg on hwy, 35 city then wrecked it.

Now I have a 97 lsi metro 3 cyl and it only gets 40mpg hwy, and 28mpg city!

What's wrong here?

It also depends on when you last drove the `90. Fuel formulations have changed and I noted a drop of about 20% when that happened. Plus the XFI was specifically designed for gas mileage whereas the LSI was not. The 70mpg (or even the loaded 60 mpg) claim seems to be atypical for a Metro. They got great gas mileage, but doing better than EPA estimates with the car loaded is outside of the normal range for that car.