luciffer

I know this is a really vague question but in a span of a week the mileage on my car drop from getting 500-550KMs per 35 liters to about 350km/35 liters (23mpg).

This is on a 1996 bone stock CX, manual.

Since it started I've changed the plugs, distributor cap & rotor, fuel filter, oil & oil filter, air filter, new exhaust manifold with built in cat and manifold gasket, new front rotors and pads, i had the back brakes checked and everythign checked out fine and had the valves adjusted.

After all this i'm still getting pretty bad mileage compared to what i was.

Obviosuly i'm trying everything any suggestions?

Malakai

sry to jack a thread, but im in the same boat only worse, i have a 98 dx man. and i only get 300-350 per tank, when it wants to. and this is about every 5 days when i fill up im using 89 octane.

thehatchninja

get a tune up...injector/fuel system cleaner, fuel filter, air filter, valves adjusted, oil change etc

and Seafoam is a good idea too.

luciffer

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thehatchninja &raquo;</TD></TR><TR><TD CLASS="quote">get a tune up...injector/fuel system cleaner, fuel filter, air filter, valves adjusted, oil change etc

and Seafoam is a good idea too.</TD></TR></TABLE>

I haven't gotten a fuel injector flush done from honda because i figured its probably a waste of money. I did add a bottle of fuel injector cleaner each time i filled up for about three tanks. its made no difference either, but i've done all the other stuff you suggested.

Anyone else?

schardbody

check for codes stored in the ECU first, but with a major drop like that its usually something mechanical.

luciffer

Sorry forgot to include, I've got an OBD-II reader and there are 0 codes showing. A few months ago i replaced the secondary o2 sensor when i got a code for that, reset the ecu and teh code was gone.

jspeed77

Well, considering your on the ball with maintenance the only suggestion i can make would be driving style. Here's some fuel stat's I noticed with my car (99 dx hatch with the stock 1.6L - 180,000km):

-Between 100 and 120km/h your car will burn as much as 25% more fuel.
-Check those tire pressures because that makes a difference if your low on air.
-Winter driving / cold temps will burn more fuel.

If I driving at about 130-140km/h hwy in the winter with aggressive shifting my car will return about 25mpg. Reduce your highway speed to 120km/h and with short shifting 2800rpm and I have returned a best of 43mpg. Use the 25% rule with summer driving and I have acheived as high as 52mpg.

Check this article out and tell me if anyone really needs hybrids!

http://www.canadiandriver.com/...e.htm

John S.


Modified by jspeed77 at 11:50 AM 2/16/2006

luciffer

That's good info jspeed77, but unfortunately i'm rarely doing any highway driving anymore just in town, and the little highway driving i do is at 110km/h...it is a bone stock cx :-)

I don't drive the card that hard and haven't noticed a drop in power since the mileage went down either. after replacing a few things with nothing changing I figured there must be a whole in the gas tank, but there's never any fuel under the car and no gas smell either.

I'm 100% lost on this one.

thehatchninja

i'm stumped too man.

check around the injectors themselves. There's an o-ring there that can leak fuel. Usually only happens on older cars tho.

EG2Driver

Tires pressure will make a big difference. I got 165 miles to half my tank (which is more like 2/3 empty) today. Usually, summertime i get 400 miles for a whole tank, or like 300 for where it was at today. Thats half!! Pisses me off but what can i do....i already drive like my grand ma'. She proly drives faster than me....but anyways. Winter/tire pressure kills gas mileage.

luciffer

So what do you guys run for tire pressure in the winter?

The car is bone stock so its on 13" steel rims and new winter tires since i live in Canada on the east coast.

I have been keeping the pressue at 30-32 psi.

hatchninja - i'll check around the injectors tonight, it is 10 years old so the o-rings could be bad.

Thanks guys.

thehatchninja

just to make sure, you don't have a CEL do you?

Kamin

primary o2 sensor. just because there isnt a code for it dosent mean its reading correctly.

1337 Si

My gas mileage went down when it got cold.

luciffer

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thehatchninja &raquo;</TD></TR><TR><TD CLASS="quote">just to make sure, you don't have a CEL do you?</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by luciffer &raquo;</TD></TR><TR><TD CLASS="quote">Sorry forgot to include, I've got an OBD-II reader and there are 0 codes showing. A few months ago i replaced the secondary o2 sensor when i got a code for that, reset the ecu and teh code was gone.</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kamin &raquo;</TD></TR><TR><TD CLASS="quote">primary o2 sensor. just because there isnt a code for it dosent mean its reading correctly. </TD></TR></TABLE>

I'd hate to spend $130 just to find out its not the problem, is there anyway to test this for certain?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1337 Si &raquo;</TD></TR><TR><TD CLASS="quote">My gas mileage went down when it got cold.</TD></TR></TABLE>

mileage goes down when it gets colder, people run their cars longer to warm up and for other reasons, but not 200km over 35 liters.

Kamin

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by luciffer &raquo;</TD></TR><TR><TD CLASS="quote">I'd hate to spend $130 just to find out its not the problem, is there anyway to test this for certain?
</TD></TR></TABLE>

you need a good oscilliscope to watch the voltages of the o2 sensor. possibly a 3-5 gas to verify how the engine is running vs. what the o2 sensor is seeing.

the tools to diagnose it will cost more than the sensor. so you can ask a shop to do it or just blindly replace parts.