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Location:
Sydney, Australia
Registered:
May 2002
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Positioning of O2 Sensor
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Sun, 22 September 2002 21:11
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Hi,
I've just picked up a set of 4-2-1 extractors for my RWD 4AGE, it doesnt have the O2 bracket yet mounted, which means I have freedom to place it where I like.
What is the best position for the O2 sensor? Is it better to have it read the mixture from more than one cylinder, or is one enough? And is there a limit on how far away from the cylinder head I can place it?
Rgrds
sam
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Registered:
June 2002
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Re: Positioning of O2 Sensor
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Sun, 22 September 2002 22:24
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If it's a 3 or 4 wire heated O2 sensor you can place it after the 2-1 part. If its a single wire I think it has to be nearer the exhaust ports to keep it hot so it works, about 15-20cm form the port.
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Mon, 23 September 2002 09:02
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Hey sam, I'm dealing with that very problem. I had the flange welded on down on the 2-1 section, first by quickfit (ended up the flange fouled on the g'box crossmember, my fault, 'cos I took just the extractors in, no car) then by Liverpool exhaust, in the same spot but without fouling on anything.
Neither place advised me about the heat factor, so it obviously doesn't work (standard 4A-GE O2 sensor).
Someone suggested to me to have 2 sensors, and a switch to switch between the 2, but talking to michael/irally about it, he reckons it would prolly still be too far away. It would certainly be further away than standard. So unless you want individual sensors for each cylinder (which would be pretty cool!) you may be stuck, unless you can use a heated one that will work ok with the standard ECU.
Can anyone tell us if there's a Toyota O2 sensor, with the standard flange, that is a heated type? And will it work with the standard ECU?
And will it totally fix the problem, being still quite far from the ports?
Seeing as I have a microtech I can use pretty much any sensor, are some better than others?
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Registered:
June 2002
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Re: Positioning of O2 Sensor
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Mon, 23 September 2002 20:40
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As I said in my last post, 3/4 wires for a heated O2 & 1 wire for non-heated.
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Location:
Sydney, Australia
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Mon, 23 September 2002 21:15
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THanks Joel,
Just out of interest how much did it cost you to have the o2 flange welded on?
I was thinking of having it put on the 4-2 section, but I think that may still be too far away. So I may just choose a single cylinder and place it pointing down 10cm or so away from the head.
I guess you could run multiple o2 sensors and have a bit of circuitry that takes an average, or somehow retrofit a heated sensor as you mention. I have no idea how the heated ones work, whether they are heated all the time or just some of the time, and whether the output is still ok for the standard ECU... have to do some research...
sam
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Location:
Canberra
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Mon, 23 September 2002 22:24
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I've been playing with exactly the same problem with my car. I know that with my Haltech, there is a variable you have to change to tell the ECU how far the sensor is from the motor, my assumption is, that you should try to keep this distance as close to factory as possible.
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Registered:
June 2002
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Re: Positioning of O2 Sensor
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Tue, 24 September 2002 03:39
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To fit a heated O2 sensor you just need power from the battery (can be done by relay off the key) and a earth (other than the O2 sensor).
EF9 Vtec civics have 2 non-heated O2 sensors (one in each 2-1 section of the cast mainfold), I think the two are just wired together.)
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I supported Toymods
Location:
Adelaide
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Tue, 24 September 2002 07:26
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I think we all have the same 4-2-1 Extractors. From a certain place in NSW???
I have to get my car through an emissions test w/ a cat and my 4ag so I was worried about where to place the sensor. My first thought was up near the outlet of say no3 or no4 so easy wiring. Like most ppl into cars, I recon I can keep a good enough eye on my engine to know what is happening. Just keep regular maintenaince and I see no problems.
However, thinking about it, I will place it at one of the 4-2 collectors. Sure it may not be perfect but 4ag will run with no Ox sensor easy, just a little rich. The other thing is that to pass the emissions test I will be flogging the crap out of the car before it does the test: this is to heat the cat up and get the Ox sensor working properly.
Anyone remember the stories on club4ag about the guys flogging their cars before the smog tests???? This is why!
Jaz
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Location:
Finland
Registered:
June 2002
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Re: Positioning of O2 Sensor
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Tue, 24 September 2002 09:50
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Just out of curiosity; how is emission test conducted in Australia?
Over here sensor is just rammed into tailpipe and engine will be let to idle while readings are taken.
That goes for petrol engines, whereas diesels get a different treatment. Diesels are romped once to redline, and soot (plus some other crap) is read from probe. If that one measurement exceeded allowed limits, then they'll romp it some more and take an average reading.
It's not uncommon to see diesel owners to make adjustments to fuel delivery pump before test - be it either lowering fuel metering or limiting top rpm.
Nevertheless neither of those (petrol & diesel) emission tests simulate real driving conditions. Are petrol cars run at tickover? Is it usual to redline your diesel on daily basis?
When these tests were adobted here in the late -90's, they broke pretty many diesel engines. Nowdays they ram a probe to also measure engine coolant temp - to verify later that diesel engine was up to normal operating temperature in case it breaks down during test.
So, how is test done in Oz ?
---
Reference, emission limits.
---------------------------CO(%)---HC(ppm)---lambd a
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car reg before 1986 - 4,5------1000
car reg after 1986 --- 3,5-------600
so called low emission
cars (w. catalysator) - 0,5------100--------1(+/-0,03)
[Updated on: Tue, 24 September 2002 09:54]
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Location:
c'town, NSW
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Tue, 24 September 2002 10:07
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they run our car on a simulation program on a dyno to simulate real driving conditions.
what it is, the car goes on a dyno and exhaust is probed, the operator drives the car watching a computer monitor, the computer monitor has a moving line on it, when the line goes up the operator has to keep the cursor near or on the line by accelerating, and vise versa when the line goes down, the test takes a few minutes with the line going up, down, plateus, quick accel and quick decel etc etc etc..
hope this is easy to understand, its sorta hard to explain.
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I supported Toymods
Location:
Adelaide
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Tue, 24 September 2002 15:51
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My test is at idle:
Less than:
2.5percent carbon monoxide
250parts per million hydrocarbon
With a cat and all things heated I expect to pass
Note: this is ALOT lower than your cars for those w/ a catalytic converter. This is why I know I will pass easy.
Modern EFI + Cat = decent numbers.
Jaz
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Wed, 25 September 2002 10:20
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While there's a few of us here with similar extractors from Liverpool 'Zorst, has anyone ever experienced cracks?
I had a crack start along a weld about 1" from the head/flange/exhaust port. I had it welded up while I was there getting a new muffler (and having the O2 sensor welded on), and then a week later I noticed another crack in the exact same place on the very next pipe (the first crack was on the no. 3 cyl, 2nd was on the no. 2 cyl).
I welded this one up myself while a mate was hiring a welder.
Then the other day, I noticed a fairly developed crack down in the join of the 2-1 section.
So I'm pissed off. Once my cars driving I gotta go back there & see what they say.
BTW, what sort of prices have people paid new? Anyone else paid $450???
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I supported Toymods
Location:
Adelaide
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Wed, 25 September 2002 10:34
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dammit prefered not to of known the above bigworm 
nah, not really, I guess I'll keep an eye out so thanks for the info.
Three of us SA AE86 guys bought them from the company that sells them to Liverpool Exh. (can't remember the name)
We paid 270 each set. (250 + 20 post) so we are doing pretty well, this is for mild steel type tho.
Hearing about the cracking and knowing a friends extractors also cracked, before my set go on, I'm gonna be getting a flex pipe. Another guyt also was loosing manifold gaskets until he put on a gbox stay on his factory exhaust so maybe you might want to look into it.
Jaz
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Wed, 25 September 2002 10:56
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Ooh, I think I have a little bracket for that somewhere, prolly won't fit but might come in handy.
Thanks for the suggestion.
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Location:
Sydney, Australia
Registered:
May 2002
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Re: Positioning of O2 Sensor
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Thu, 26 September 2002 03:32
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I got my set for $277 up at Stuart Wilkins Rallying at Mulgrave.
thanks for the tips.
rgrds
sam
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Location:
Finland
Registered:
June 2002
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Re: Positioning of O2 Sensor
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Thu, 26 September 2002 08:32
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I thought I'd mention the obvious.
In rwd application you have made sure the entire exhaust has a chance to rotate around it's own axis - right ?
If piping along chassis is securely bolted onto car (or in some way that rectricts rotating action), the pipe will stress exhaust header.
What happens in acceleration is that engine mounts give in a little, thus let engine to tilt a bit to one side. If this movement in piping is limited close to zero on the underside of car, the exhaust manifold will receive hefty twisting torque.
In gravel rallying cars racers usually fix the pipe in such manner that it will relatively easily get ripped off when accidentally driven off the road. This is to limit damages. After such event one usually do not have to buy a new exhaust manifold, just the piping.
-A.
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