installed xfi cam should i install ecm

installed xfi cam, only slight mpg gain. 1-1.5 mpg gain fist tank, xfi parts car is a 1990 and has egr system with no vacume advance. driving 91 no egr with vacume advance. will the ecm work with different system THANKS FOR YOUR HELP

The biggest advantage of the XFI cam is that it allowed the engine to work with a much taller gear ratio. The gears are what provided most of the mileage increase, the improved torque curve merely worked with it.

THANKS WOODIE i have notist it pulls hills with less stain. i have read conflicting info on the gear ratio's between the xfi and metro-lsi . some say xfi has taller gear and some say the metro-lsi gearing is taller. im driving metro with lsi motor and trans with xfi cam. i happen to have one of each, im just tring to get the best combination. the lsi has been rolled /xfi has bottom end problem and body damage. the metro is in best shape so im tring to get the best possible car any info would be appreciated thank RANDALL

XFI had 3.79 final gear ratio
Convertable had 4.39
All other 89-94 had 4.10

The 98 - 01 four cylinder cars also have 3.79 if you're planning a junkyard shopping trip. Or, just get 13" wheels.

thanks WOODIE i'll check and make sure the x fi has original trans and hopefully change it out soon. if i change trans will the instrument cluster read correctly or do i need to change it as well thanks again RANDALL

Nope, the speedo gears are inside the transmission, as long as you don't change wheel diameter the speedo/odo will remain correct.