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andrewgoh andrewgoh is offline
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Join Date: Oct 2002
Posts: 335
Re: Passed Emissions...But Poor Gas Mileage..

Originally posted by andrewgoh
I passed WA state emissions test yesterday, but I discovered that my mileage is poor on my recently purchased 1986 944T. It is running somewhere around 13 to 15 miles-per-gallon for 1/2 urban driving, 1/2 highway. I understand that it should around 20 mpg.

Can anyone help? Any ideas what what I should check to correct the problem? My idle rpm is running around 1000 - 1100 rpm. Using 245R16 for rear tire setup. Here are the test results:

THANKS in advance!!!


HC Cruise Limit: 150
HC Cruise Emissions: 150 (passed)

HC Idle Limit: 150
HC Idle Emissions: 150 (passed)


CO Cruise Limit: 1.1
CO Cruise Emissions: 0.46 (passed)

CO Idle Limit: 1.2
CO Idle Emissions: 0.01 (passed)


CO + CO2 Cruise Limit: 6
CO + CO2 Cruise Emissions: 15.76 (not applicable)

CO + CO2 Idle Limit: 6
CO + CO2 Idle Emissions: 15.51 (not applicable)


O2 Cruise Limit: Not applicable
O2 Cruise Emissions: 0.38

O2 Idle Limit: Not applicable
O2 Idle Emissions: 0.11

An update...just got the recently purchased 951 back from the shop...shops says that the PO used silver-tipped spark plugs, and should have used copper tipped plugs (or was it vice versa?)....and the K&N box-type air filter was filthy....cleaned it rotors and plug wire were change a year ones not needed....

Let's hope this improves the 15 - 17 mpg mileage....
Old 04-11-2003, 09:27 PM
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