bsm123

hi, my other topic on sluggish acceleration is not related to this as this happened quite a while ago.

well anyway i had a check engine error last time and found out it was the o2 sensor. mileage was bad during that time, obviously coz the o2 sensor needed replacing. well, i replaced the o2 sensor, CEL went away and thought everything would be back 2 normal. but it just improved slightly. then i found out that the sensor i changed it with was not from a b18c-r even though it was a four-wire type. so i managed to get a proper b18c-r one and changed it thinking that then it my mileage should definitely be back to normal. but im still getting around 100+ km less than what i used to be getting which was around 450km easily on a full tank. now im getting just over 300, maybe 320 or so.

ive tried checking a few things,

-no fuel leaks
-in my other thread i mention a leaking gasket which supposedly has been there for a while, after fixing that it's still the same.
-air/fuel ratio seems to be very consistent as per the last dyno

i dont know what else could cause this. my usual driving style is minimal vtec engagement and even then for very short periods. i used to be able to get around 450km with that. now even if i dont engage vtec at all im getting really bad mileage.

any help is appreciated.
thanks alot.

lazlong

It could be a lot of things but, with the exhaust problems I think your cat may be going bad. To be sure, hook up a diagnostic tool and see if any DTCs are stored and post any DTCs you have.

anti-civic

most people don't know this, but gasoline companies have a "winter blend"
don't ask me why, but they do. im pretty sure that there's more ethanol in the winter blends, and it takes 30% more ethanol to do the same work as gasoline.
so if you get the same gas at the same gas station every time you fill up, it would seem that you just hit a brick wall as far as gas milage goes if they just switched over to the winter blend.

make since(except for why they would have a winter blend)?

Kennykid2002

iTrader: (1)

Because Ethenol is cheaper
Because Ethenol doesn't evaporate so quickly in the winter

It's the same question as "Why do perfume/juice companies dilute with water?"
because....$$

Better if i sold 100 bottles of shampoo at 70/100 concentrate at $5 each
than to sell 70 bottles of 100 concentrate at $5

Everything is a business, no one seems to notice
even public schools are a business

Sorry if im getting more and more off topic :P

bsm123

oh ok. i was kinda wondering that too but wasnt sure how to check it. erm, what kinda tools are we talking about? air/fuel sensors? ecu diagnostics?

bsm123

erm...ok. sure havent heard of that before. does that apply even for countries that do not have seasons at all? or is that just what they call it and do it without anyones knowledge?

lazlong

It's a different blend of gas and ethanol. They do it with everyone's knowledge but, we can't do anything about it.

lazlong

A diagnostic tool is a hand held computer that you plug into the OBDII socket ('96 and newer) under your dash. Most auto parts places have a scan tool, and they'll scan it for free or nearly nothing.

anti-civic

i don't know about the no season's thing....
i know that there's one place around where i live that sells gas without ethanol in it, never got it though, i don't get gas from dinky country places.
my friend drives a 95 ford ranger and says he gets like 26 mpg with it.

bsm123

but that much difference? over 100km less? and wouldnt everyone else where i come from be complaining then?

bsm123

oh ok. ive had that used before when i was having my o2 sensor problem. as for the cat con, what do i check for on the computer? as there wont be any errors right? coz my CEL is clear. which stats do i check to make sure the cat con is working fine?

thanks.

anti-civic

it differs from the different gas companies.
some, you might not notice a difference, and some, it will deffinatly be different, again,, just depends on alot of stuff, like your car, driving style, location, gas grade, ect.
i run shell 89 octane on a basically stock 95 neon and i can get up to 40 mpg. if i use 87 or 93, i get like less than 30. i should be able to tell the difference when they switch over because i use the same exact gas every time.
but before, i used only pilot gas, and consistantly through the year, i would get the same gas milage year around, in a different 95 neon.

bsm123

is there a way to know that ur cat con is going bad other than fuel consumption? also im definitely beginning to suspect it coz i heard driving around too long with a bad o2 sensor could damage ur cat con. and i was driving around with a CEL on for a while as had problem obtaining the same sensor for my engine. so could it be that my cat con needs to be changed?

bsm123

btw i dont have a sensor where the cat is. i know some engines do. so i dont think the error would show on the computer right?

lazlong

Mine was definitely sluggish when my cat went bad but, my MIL came on. GO GET THE CODES READ, IT COULD HAVE A CODE AND NOT SHOW ON THE MIL.

In the meantime:
It kinda seems like a throttle problem. With the engine off, take your airbox/CAI off. While looking down into the throttlebody move the throttle with your hand and look and see if the throttle valve and/or shaft are too loose or too tight. Also look and see if the throttlebody is real dirty, if it is take it off and clean it with carb cleaner.

Still reading on the cat system in the book, I'll get back when I have something more.

bsm123

ok will go check out with the computer 2moro. i was reading some stuff on cat cons on the net and it definitely seems as though the bad o2 sensor could have caused the cat con to screw up. as i remember i was running rich for quite a while.

lazlong

Ok, OBDII was instituted expressly for emissions, meaning that the comp automatically tests for emissions, which would automatically set a code.

You can check the cat yourself by lightly tapping on the cat with a rubber mallet and listen for a rattle. That rattle is loose substrate and you need to change the cat.

Otherwise you can take it down to the shop and have them put a gas analyzer in the tailpipe and compare your emissions to the standard.

sdaidoji

iTrader: (1)

bsm,

which country are you from? depending on the coutry, you could get "not-so-optimal-fuel" depending on where you refill...
And if the problem is the cat, caused by the o2 sensor, it will mean it will be clogged, and that means your engine will feel like you would if somebody plugged your "back hole" - it would not be pleasant, but if that true, you will have loss of power for starters. If you did dyno it, it should have been detected as loss of power.

bsm123

hmm. well the other day when i was repairing the leaking gasket, i told the guy to check the cat for me and he knocked it lightly with a wrench and said it was fine. still have to check with the comp then.

bsm123

hi sdaidoji, im from malaysia. and from what i know the fuel is pretty standard here. i usually fill shell, although always from different stations. but i would still get at least about 450 on a full tank.

could there be something else wrong with the cat? i mean something that could just cause bad fuel consumption but power still there?

thanks.

bsm123

if there is no sensor after the cat convertor, and the cat is going bad, will there still be increase in fuel consumption? i only have a sensor before the cat

bsm123

also could a bad fuel filter cause this much increase in fuel consumption?

im really stumped and coming to a dead end not knowing what else to look at.

DEX200K

My cat went bad because of a cracked manifold that caused the sensor to mix the fuel so rich it clogged the cat material. Eventually I could barely get to highway speeds.--Dex

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