R33 Fuel Efficiency

[J_Red33]

So even if my 96 S2 has around 54,000 KMs on the odometer I should replace my O2 sensor?

Hmmm I might do that at the next service... dunno whether to get the EL falcon O2 sensor or buy a genuine R33... any advice?

With the kind of economy you are getting I'd say your O2 sensor is fine at the moment, so no stress, however if you start to notice any economy drop, definantely change it. It's actually more to do with how much engine running your engine has done. If it was a city car it would have done a lot more engine work relative to the kays.

5 years was just a general estimate, sorry if that was a bit misleading. My car actually has less kays on the clock, but I'm pretty sure it was a city car (it was unbelieveably clean) & the O2 still died.

It is still good practice to do it before it becomes a problem however. My car became a bit of a pain to drive, stalled really easy. You can then keep it as an emergency spare too.

sir d - NTK make a direct replacement for about 100$ odd dollars.

It's pretty much the same price as the el sensor, but has the correct plug.

I disagree with you guys. I have a consult screen, and I have have used the consult interface with my laptop to graph the o2 sensor output.

My fuel economy is shit - about 300ks to a tank. But the o2 sensor is fine.

Yes well that's what the consult tells you, but if you are only getting 300 kays to a tank then your O2 sensor is in fact reading incorrectly. O2 sensors read lean with a lower voltage & when they start to get old, usually the start to read low. The ECU trusts it's reading & then compensates with extra fuel (ie richening up the mix) to get the correct reading. If the fuel being used is not outside a set range (& it can be fairly broad) then it will not spit the dummy).

Once again if you've never changed it, you should do it anyway. O2 sensor changes should be looked as being a consumable, just like oil as they do deteriorate from the exhaust heat over time.

Edited November 3, 2006 by JazzaR33

[MBS206]

Plus, O2 sensors don't spit the dummy until they're basically utterly useless. That's when the Computer detects an issue.

[J_Red33]

^^ Yep I never had the check engine light come on even if it was disconnected. They can shit themselves very suddenly, but it's relatively rare in comparision to normal degradation failure

Edited November 3, 2006 by JazzaR33

[PobodY]

factory fuel tanks take 65liters of juice

Well, maths has never been my strong point - that's why I failed engineering.

All I know is that I pull-up, put the nozzle in, run it until it stops... then a little bit more.

The bill comes to between $60 and $70 - which would make sense for ~65L (or just under as I don't run it dry). I reset the tip-meter and off I go again.

Usually it reads just under 500km before it's time to fill-up again (if my wife has been driving mainly - it's more like 450km if It was mainly me).

I figure that's normal economy for an unmodified RB25DET with an automatic box.

[moobaque]

Hey all,

I've certainly taken on board all ur responses and at the end of the day will prolly change both the fuel filter and o2 sensor. But hopefully next week it will be going on the dyno for a diagnostic and i might find out for sure whats going on

Thanks!

Cam

[RPR33]

my car must be stuffed......

It has 88,000 on the clock frount mount and 3inch turbo back

I get like 280 to 330kms out of a tank and thats not hammering it everywhere...

It idles on like 12:1 so I was told by the dyno op and when down to the 10:1 on WOT rich as.

not sure wats wrong with it but the ecu has a ksp tuning sticker on it so that may have something to do with it??? the dyno op just said run or boost

Gonna replace the 02 sensor I think for a start!

[Munkyb0y]

i dont know why everyone carries on about 02 sensors so much. they dont really help economy, unless you're cruising / very light throttle. i changed mine and it made no difference at all.

i'd be testing it before changing it for nothing. do a search, theres a simple way to test it with a multimeter i think.

never heard of a fuel filter causing bad economy before. maybe a dirty/blocked filter would cause inconsistent fuel flow or something. but if your engine is running smoothly, how would it affect economy ?

[mid life crisis]

i find this thread quite interesting i have a r33 auto /apexi pod filter /hybrid fmic /3 inch front pipe to cat the 4 inch all the rest of the way thru .i was getting around 380 ks to a tank since replacing the o2 sensor last week i filled up the tank and driving it the same as i always do i have now done 430ks and the needle is just under 1/4 tank at the moment . i will drive it till the light comes on then fig out my litres per hundred when i know how many litres it takes to fill up again. ther car dosent smell of unburned fuel any more at idle and seems to have fixed a stalling problem i had b4 so i guess the o2 sensor does play a big part in the overall running of the car

cheers mid life crisis

[Munkyb0y]

i'm guessing you do alot of highway kms?

coz that's where the 02 sensor would play a role.

but like i said, before, test it before you change it imo.

[Busky2k]

Well basically the stock ECU will run 14.7:1 for everything but full throttle. So it is an issue when most of us are only full throttle less than 3% of the time we are driving. O2 sensors get lazy as they get old and yeah they are worth replacing for sure. Sometimes the O2 heaters burn out and thus it takes the sensor a while to warm up, wasting extra fuel from a cold start.

Also I disagree that a fuel filter will help economy. If its clogged, you'll be running lean and the car'll run like crap.

[Munkyb0y]

i was under the impression that the o2 sensor only acts while the car is at very light throttle. ie cruising.

under anything more than that, it's not used by the ecu to determine anything. i've been told this by several tuners/mechanics. surely they cant all have it wrong.

edit: dont get me wrong, i'm all for having a functioning 02 sensor, but i dont know if this is the magic answer to the economy question. it wasnt for me.

Edited November 5, 2006 by Munkyb0y

[mid life crisis]

most of my driving is metro with a bit of boosting now and them most times im fairly light on the throttle tho

[siddr20]

Fuel filter has been proven to help fuel economy on normal cars..

So im sure this is the same for normal imports..

I even remember going into the toyota office, and they mentioned on some board that changing your fuel filter will help towards better milage.. They even had a old fuel filter showing all the crap on it..

[Munkyb0y]

where's the fuel filter on an r33. somewhere under the plenum side in the engine bay?

i might change it for the hell of it. it's only about $15. i'll be shouting you all drinks if it improves my economy. lol.

[Race_Bred]

A few of you have mentioned your cars stalling, i just wanted to know, when exactly do they stall?

i have a fmic, 3 inch exhaust and 10 pounds of boost, i do on average 300km per tank, filled to the top. i do give it a bit of a hard time.

Anyhow, if im cruising along and have to suddenly get on the brake and put the clutch in, the revs drop too low, and sometimes it stalls, its the only time it does it, just wondering if that was a similiar stalling problem that the rest of you were having?

Edited November 5, 2006 by Race_Bred

[Busky2k]

i was under the impression that the o2 sensor only acts while the car is at very light throttle. ie cruising.

Hook up a multimeter to an O2 sensor and see how it behaves. On 3 different cars I've logged, bascially its running closed loop (ie using the O2 sensor feedback) even at full throttle at lower RPMs. On the cars Ive sussed, it only goes to open loop above 3500rpm _and_ full throttle. So even medium throttle its in closed loop, and idle too.

So yeah but changing the O2 sensor on every car won't improve economy - its merely one part of many that can affect fuel economy.

[Munkyb0y]

A few of you have mentioned your cars stalling, i just wanted to know, when exactly do they stall?

i have a fmic, 3 inch exhaust and 10 pounds of boost, i do on average 300km per tank, filled to the top. i do give it a bit of a hard time.

Anyhow, if im cruising along and have to suddenly get on the brake and put the clutch in, the revs drop too low, and sometimes it stalls, its the only time it does it, just wondering if that was a similiar stalling problem that the rest of you were having?

look up 'cleaning aac valve'. seems to be a common cause.

i had this problem, but only happened rarely, turned out to be the atmo bov, so i plumbed it back, prob solved.

[mad082]

i changed my o2 sensor a few months back. economy didn't change. then i developed a slight miss at idle. finally got it sorted a few weeks back. in the process i changed back to my old o2 sensor, and put a new fuel filter in and cleaned my afm. my economy has improved. i have rather a heavy right foot and i do a lot of spirited driving. i can't remember exactly how many k's i've done this tank, but i think it is about 250k's to 3/4 of a tank. normally i would get about 200 to 3/4 of a tank, but i'll know for sure when i fill up. normally i was getting about 17L/100k's.

so it may be worth cleaning your afm as well. and if you don't want to buy a new o2 sensor, just try giving it a clean with carby cleaner first.

[Munkyb0y]

got a part number / brand for the r33 s1 fuel filter?

[Busky2k]

Don't clean your O2 sensor with carby cleaner or other solvents - you'll just be doing damage. They aren't cleanable, only replacable.