93 Civic, mpg not so good.

[dlb]

this is my go-to list when i encounter poor mileage:

tire pressure
wheel alignment
dragging brakes
extra cargo weight
ignition timing
air filter
dizzy rotor
dizzy cap
spark plug wires
spark plugs
vacuum leaks
correct vacuum routing

reading through this thread, it looks like you've already covered most things on my list. i would still check for dragging brakes though (jack up each corner and spin the wheel—it should spin with minimal resistance), wheel alignment, and vacuum leaks. did you mention if you looked at the spark plugs? i think i saw that the cap and rotor were replaced recently.

good luck.

[night9]

Coasting in neutral sounds like the right way to approach these long hills, in your case at least. When I reach a steep hill I leave my car in neutral because it cuts fuel to the motor and it keeps me from having to use my breaks as much. Log slow hills I use neutral coasting. EOC would also help if you were willing to shut the motor down.

[liquidzorch]

Originally Posted by dlb

this is my go-to list when i encounter poor mileage:

tire pressure
wheel alignment
dragging brakes
extra cargo weight
ignition timing
air filter
dizzy rotor
dizzy cap
spark plug wires
spark plugs
vacuum leaks
correct vacuum routing

reading through this thread, it looks like you've already covered most things on my list. i would still check for dragging brakes though (jack up each corner and spin the wheel—it should spin with minimal resistance), wheel alignment, and vacuum leaks. did you mention if you looked at the spark plugs? i think i saw that the cap and rotor were replaced recently.

good luck.

Yes all that has been checked. Everything is stock and all vaccum routes are stock. No leaks, plugs, cap, rotor and wires changed. I have been playing with timing but there has been no change in mpg.

[E.Roy]

Did you replace the 02 sensor? Rockauto or ebay for a Denso or NTK sensor, i just bought a Denso for my Corolla on ebay for $39

[liquidzorch]

Originally Posted by E.Roy

Did you replace the 02 sensor? Rockauto or ebay for a Denso or NTK sensor, i just bought a Denso for my Corolla on ebay for $39

The oxygen sensor was bench tested, and found to be good. Still not a bad idea since it is not so new. I just dont want to spend 50usd (price here in mexico for oxygen sensor) on something that might not help mileage.

[slownugly]

Are you throwing it in neutral when coasting down hill? Leaving it in gear is the better route because it activates dfco. Idling in neutral when coastin uses fuel in these cars. When approaching lights or stop signs downshift without touching the gas pedal.

My stock 93 lx consistently got 40 mpg highway. That's not at 5000 feet but you still should yield better than low 30s.

[liquidzorch]

Originally Posted by slownugly

Are you throwing it in neutral when coasting down hill? Leaving it in gear is the better route because it activates dfco. Idling in neutral when coastin uses fuel in these cars. When approaching lights or stop signs downshift without touching the gas pedal.

My stock 93 lx consistently got 40 mpg highway. That's not at 5000 feet but you still should yield better than low 30s.

This week I have been trying with leaving it in gear downhill, and downshifting to stop. But still have not seen much improvement. It has helped a little, but it has not helped enough to raise a whole number in mpg.

I would like to find the fault for this, I will be buying new injectors soon, and check that since one of my injector leaks a little bit when off. It has been tested and they say it does not inject more that the others, but still, hopefully it will help a bit.

[slownugly]

I read you replaced the tps. Is it adjusted correctly? Should read .45-.5 volts closed throttle

[liquidzorch]

Originally Posted by slownugly

I read you replaced the tps. Is it adjusted correctly? Should read .45-.5 volts closed throttle

Good question. It is at exactly .45v when closed. And I check it every couple days to make sure it has not moved.

[dlb]

i meant to mention before that your compression #s are fine. they show the engine is marginally worn but will still last forever if maintained properly, and with no noticeable loss of power. i know guys driving around with 120 psi on all cylinders and they're still getting good mileage. their cars just lack some zip, is all.

next question, is your odometer or trip meter accurate? you can compare it against GPS, or the old fashioned method of taking note when you pass by km or mile markers on highways.

also, if your tires are larger than stock your speedo and odo will be off. sounds like yours are probably stock but i want to rule out as much as possible.