Thread: Running 2002 GTP w/o cat = bad MPG???

Originally Posted by motoshrump

Ok, so my best option is just to disable the routine O2 sensor reference. How do I go about doing that? As far as driving style goes I rarely go WOT and use the s/c for the few hills along the highway between home and the city. Cruising at speeds of around 65-70 mph. Prior to the cat getting removed MPG's were substantially better even with wore out plugs and wires. The car only has 95,000 miles on it and I run 91 octane fuel. I just refilled the car and it worked out to 18.4 MPG. The onboard computer is saying that I am getting 19.6 MPG.

Vacuum leak? Have you check for any of those? Might have some dry rotted "T" fittings around the S/C, LIM, Fuel Rails...I'd check those...you get some pretty craptastic MPG's with a vac leak...you can spray some carb cleaner around the engine bay while its idling...if the idle changes and it sucks in the carb cleaner...you might have found your issue