kenpdx Posted April 22, 2011 Share Posted April 22, 2011 97 Leggy 2.2 auto tranny with 193,000 miles. I've been getting increasingly worse mileage the past 6 months (from 29ish overall to 20-22 MPG). The following have been addressed: New 02 sensor, fuel filter, air filter, oil change/w filter. So, WTF? Plugs (NGK) are recent, I checked them and re-gapped them, wires are kinda old, no idea on EGR, and PVC valves. Ideas, comments, funny embarrassing stories? Quote Link to comment Share on other sites More sharing options...
bstone Posted April 22, 2011 Share Posted April 22, 2011 Get a bottle of SeaFoam. Put 1/3 in the gas, 1/3 in the crankcase and 1/3 into the vacuum intake. It's smoke like a mofo and get tons of carbon out. Change the oil about 50 miles later and reclock the MPG. Quote Link to comment Share on other sites More sharing options...
Olnick Posted April 22, 2011 Share Posted April 22, 2011 I would definitely replace the plug wires--use Subaru OEM only. Would also replace the PCV, plus clean the hoses leading to it and check them for splits & cracks. Sorry, no embarrassing stories, none that I'll tell here anyway! Good luck and let us know. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted April 22, 2011 Share Posted April 22, 2011 No codes? CEL works? ECT sensor is a common failure, tends to cause driveability issues but could also lead to poor fuel economy. Which O2 sensor was changed? Front or rear? Quote Link to comment Share on other sites More sharing options...
kenpdx Posted April 22, 2011 Author Share Posted April 22, 2011 No codes? CEL works? ECT sensor is a common failure, tends to cause driveability issues but could also lead to poor fuel economy. Which O2 sensor was changed? Front or rear? Front was changed with OEM. The car actually runs well, a little "off" but not anything super noticeable, just crappy mileage. Quote Link to comment Share on other sites More sharing options...
kenpdx Posted April 22, 2011 Author Share Posted April 22, 2011 Get a bottle of SeaFoam. Put 1/3 in the gas, 1/3 in the crankcase and 1/3 into the vacuum intake. It's smoke like a mofo and get tons of carbon out. Change the oil about 50 miles later and reclock the MPG. Getting some today. Quote Link to comment Share on other sites More sharing options...
Suba9792 Posted April 22, 2011 Share Posted April 22, 2011 Check your knock sensor as well, I have heard that it can cause poor fuel economy not sure on that but mine is getting better mpg since the replacement, odds are yours has never been replaced and its most likely cracked, RockAuto has OEM ones for about $50. I'd also look into your coil as well, they tend to not fail but mine was biting you when it was touched, after the new one no probs and noticeably better fuel mileage. When I changed out my PCV valve on my 2.2 it was very gummed up and so was the hose leading to it, I just used some brake cleaner and cleaned out the hose and dropped in the new valve and my idle smoothed out greatly. Odds are you just have some dirty old part that either needs replacement or cleaning(EGR). Quote Link to comment Share on other sites More sharing options...
Suba9792 Posted April 22, 2011 Share Posted April 22, 2011 No codes? CEL works? ECT sensor is a common failure, tends to cause driveability issues but could also lead to poor fuel economy. Which O2 sensor was changed? Front or rear? ECT?? what is that. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted April 22, 2011 Share Posted April 22, 2011 Engine Coolant Temperature. Quote Link to comment Share on other sites More sharing options...
Suba9792 Posted April 23, 2011 Share Posted April 23, 2011 sweet another sensor to add to my list of "I know what that is":banana: Quote Link to comment Share on other sites More sharing options...
kenpdx Posted April 23, 2011 Author Share Posted April 23, 2011 SUCCESS!! It would appear plug wires, PCV valve and a can of SeaFoam (holy god, what a cloud of nastiness) has done the trick. Primarily the wires I think, the old ones were pretty haggard. Thanks for all the input, folks! Quote Link to comment Share on other sites More sharing options...
Olnick Posted April 23, 2011 Share Posted April 23, 2011 You're welcome! Quote Link to comment Share on other sites More sharing options...
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