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Sudden decrease in MPG, after TLC


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'95 Legacy 2.2, 5spd, w/233K: replaced driver's side head gasket 'cause I wrongly thought it was leaky. Replaced the cam seals, timing belt, OEM thremostat and belts, and Seafoamed it. Car seems to run great, but mileage has dropped from 25-28 city down to 22. I'm bummed. Also, sometimes if I don't downshift on an incline, it sounds and feels like it's running on three cylinders. I push the clutch in, rev it, downshift, and it sounds and runs okay. It has a new O2 sensor, air filter, plugs and wires. No check engine light on,though. This drop in MPG happened after I lovingly massaged it, too! I'm open for helpful hints and advice. If the ECM was possessed, would it show up as a CEL? I can't stand getting piss-poor mileage after all this time of beating the system. Help!icon9.gif

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How about new fuel filter? Clogged injectors?

 

Spark plug gap?

 

And as aggravating as it sounds, maybe double check the timing belt placement - if it is off a tooth.

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I'm thinking T-belt too. One side might retarded by only a tooth ...which'll wreck your cruising efficiency & torque, but it'll come alive when you rev it out. Overall it would feel a little rough.

 

**** ******!

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(Gr-o-a-n-n-n) OK. I was thinking the same thing. At least now, I know how to do it more quickly. Whaddya' think about an engine temperature control (?) sensor? Think that would or could make it run rich all the time? The tail pipe is sooty!

 

Thanks for the additional brain useage.:clap:

Rick

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25-28 sounds very high for city driving. That's about right for highway. 22 is right where it should be for city. Perhaps you haven't driven enough since the repairs to establish a good track record. A single tank isn't enough of a predictor. Also, perhaps the fuel at your filling station has recently been changed to a mixture containing ethanol, which will always result in a loss in fuel economy. There could also be other problems as you've been talking about, but I don't think that 22 mpg should be completely unexpected.

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How about new fuel filter? Clogged injectors?

 

Spark plug gap?

 

And as aggravating as it sounds, maybe double check the timing belt placement - if it is off a tooth.

 

Fuel filter is new, as are plugs; the car was running well until my overheating episodes, which is why I thought the head gasket was leaking. I'll check the timing again on 05/20/06

 

Thanks,

Rick

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i have a maybe related question, why did you think the HG was bad?

 

nipper

 

The car was spiking a temp. I added coolant, repeatedly; not much mind you, but I had to top it off. In hindsight, I think it was airbound. I removed the spark plugs, and the two front ones (1 & 3) were dark, and the two rear ones (2&4) were lighter, so I thought I had leaking gaskets at 233K. So, I removed the driver's side, only to discover it was okay. Then went on to replace the timing belt, the cam seals, the thermostat with an OEM one, the belts and an oil and filter change. Ya'd think the car would be grateful. Being a 5 spd, and driving sensibly, I got at the miniumum, 25 mpg. But now, after the work, only about 22. This is not specifically city driving, but suburban commuting, between 35-55 mph, and few stops. I don't think that the switch to 10% ethanol is the problem. The inside of the tailpipe is really sooty, whereas before it had a minimum of carbon residue. :-\

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25-28 sounds very high for city driving. That's about right for highway. 22 is right where it should be for city. Perhaps you haven't driven enough since the repairs to establish a good track record. A single tank isn't enough of a predictor. Also, perhaps the fuel at your filling station has recently been changed to a mixture containing ethanol, which will always result in a loss in fuel economy. There could also be other problems as you've been talking about, but I don't think that 22 mpg should be completely unexpected.

 

Thanks for your reply. Before the overheating incidents, I was getting at least 25 mpg in suburban commuting, with 28-31 hwy. I don't think it's ethanol related. I'll re-check the timiing marks tomorrow. For the past few weeks, we've had continual rain here in CT, and this weekend looks promising.

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