68 replies to this topic

[Soop]

Redback mufflers are good. Straight through mufflers will never be real quiet tho .
From memory the Coolant temp sender (The brown 2 wire ECU sender, which is the one you need to change) is $57 from Subaru.

A wide band 02 sensor wont work. You need the Narrow band 02 that is already in it. The ECU wont be able to convert the signal from the wide band, therefor it wont actually function.
How ever, if you have a spare $300 odd dollars you can get a wide band Air/fuel guage.
Plumb the Sensor into the collector on the extractors, and wire up the receiver/converter under the dash, then mount and wire in the guage, and you'll have a constant digital numerical number telling exactly how much fuel is not being burnt.

See here for more info:
http://www.innovatem...oducts/kits.php

Note, that isn't at all necessary, nor will it actually serve much purpose with a standard ECU and standard tune. But its something i thought you may be interested in.

[SUBARU]

Redback mufflers are good. Straight through mufflers will never be real quiet tho .

OK! I'll retract my last comment then!

[Soop]

Hrrrmmmm...

To check for an exhaust leak, shove a rag in the end of your muffler and get under the car, no need to rev it, you may not be able to hear it, but you've also got to feel for it.

If you've been told you need a new sensor, why on earth wouldn't ouy get that fixed? It's probably the source of alot of issues.
Bad O2 sensor will be ruining your engine, your performance and your economy, but will have not much to do with the sound of the exhaust.

Pop and crackle and farty exhaust sounds won't be fixed until you put a resonator on it and a different muffler. Get rid of the muffler, it sounds cr@p. Get an MRT one, or Xforce or magnaflow, something that's nice and sublte and is tried and tested.

What is your exhaust setup anyway? In terms of dimensions e.t.c.

02 sensor will change what sound the exhaust makes, if the car runs rich.
IIRC the 02 sensor is only active when the engine is under progressive load. I.e accelerating.

The ECU reads the o2 signal and compares what is physically coming out of the exhaust, to a pre-determined optimal Air/fuel ratio for that particular load.
The load is determined by a few sensors. Mainly the Throttle position sensor, and the Air flow meter.
This combined with the 02 sensor the ECU can determine what the driver wants, and what the engine has to work with.

So if the o2 sensor is failing, and telling the ECU that the engine is running lean, it will pump more fuel in. If the engine doesn't have sufficient oxygen to burn, it cannot burn the fuel. So it gets expelled on the exhaust stroke. Once the unburnt fuel makes it into the exhaust pipe there is sufficient oxygen and heat for it to ignite. Thus your back fire, or the popping and crackling.

That's a reaaally basic run down of it. There are a lot of other components that the ECU takes into account also.

Edited by Soop, 29 August 2008 - 10:14 PM.

[Blaeven]

02 sensor will change what sound the exhaust makes, if the car runs rich.
IIRC the 02 sensor is only active when the engine is under progressive load. I.e accelerating.

The ECU reads the o2 signal and compares what is physically coming out of the exhaust, to a pre-determined optimal Air/fuel ratio for that particular load.
The load is determined by a few sensors. Mainly the Throttle position sensor, and the Air flow meter.
This combined with the 02 sensor the ECU can determine what the driver wants, and what the engine has to work with.

So if the o2 sensor is failing, and telling the ECU that the engine is running lean, it will pump more fuel in. If the engine doesn't have sufficient oxygen to burn, it cannot burn the fuel. So it gets expelled on the exhaust stroke. Once the unburnt fuel makes it into the exhaust pipe there is sufficient oxygen and heat for it to ignite. Thus your back fire, or the popping and crackling.

That's a reaaally basic run down of it. There are a lot of other components that the ECU takes into account also.

that's almost exactly what i was thinking...

ok then... where do i get an O2 sensor from???

oh, and for those who care:

my exhaust is 2.25 press bent with 1 resonator and a redback straight through muffler...

and it's fcuking loud...

Edited by Blaeven, 29 August 2008 - 10:26 PM.

[Soop]

Subaru, but you'll need to take Lube and about $11ty. You could also go to Repco or any of those places. You need a bosch 3wire o2 sensor.

[Evil_VZ-T]

The 02 sensor receives a voltage ranging from 0.01 > 1.00v. if this voltage is interrupted by either a short or faulty connection the ecu may receive a incorrect single and too much or too less fuel may be injected into the engine causing problems. 1.00v being rich, 0.01 being lean. as you drive normally the voltage goes fro 0.01 to 1.00 many times a second as its trying to read the mixtures from each combustion and get as close to 14.7:1 as possible test the wiring before you change the actual sensor. the o2 sensors heat up at 250 degree's C these days as they have a in built heater that gets the to the operating temp alot quicker.

Edited by Evil_VZ-T, 29 August 2008 - 10:39 PM.

[Blaeven]

The 02 sensor receives a voltage ranging from 0.01 > 1.00v. if this voltage is interrupted by either a short or faulty connection the ecu may receive a incorrect single and too much or too less fuel may be injected into the engine causing problems.

1.00v being rich, 0.01 being lean. as you drive normally the voltage goes fro 0.01 to 1.00 many times a second as its trying to read the mixtures from each combustion and get as close to 14.7:1 as possible

test the wiring before you change the actual sensor.

the o2 sensors heat up at 250 degree's C these days as they have a in built heater that gets the to the operating temp alot quicker.

how do i test the wiring...?

[Soop]

Multi meter at either end of the wiring would be my guess. I'd just get a new o2 sensor and water temp sender. (Remember the Brown 2wire ECU sender.) And see what happens, I really doubt its the wiring.

[boost]

Grab an extension lead.. Remove the FEMALE plug (you can simply cut it off, it will reattach later) Expose the ends of the three coloured wires. Attach Blue to Pin 4 of the ecu, black to you ACC circuit (any red wire under dash) and green to EARTH Plug into mains and switch on power. You will smell burning, this is normal.

[Blaeven]

Grab an extension lead..

Remove the FEMALE plug (you can simply cut it off, it will reattach later)

Expose the ends of the three coloured wires.

Attach Blue to Pin 4 of the ecu, black to you ACC circuit (any red wire under dash) and green to EARTH

Plug into mains and switch on power.

You will smell burning, this is normal.

thanks for a really helpful post...

i can only hope that everyone i ask for help can be as friendly and direct as you are...

*shakes head*


for anyone who cares...

i replaced the rear muffler (it was a 'supercat' muffler, not redback) with something quieter (not sure of the brand)... now it sounds sporty but not loud... which is really what i wanted in the first place...

also reset the ECU again and decided to run it on 98 anyway (waste of petrol or no...)

for some reason it feels a little faster to accelerate... though it also feels like it's gained some low down torque...

mind you, this is probably almost definitely all in my head...

we'll also see how we go with fuel economy (140km at about 1/4 of the tank, so i think we're doing ok so far)... though i dunno what (if anything) has changed... more back pressure perhaps??? i dunno...

i'm still going to replace the temp sensor and O2 sensor when i can find a place that sells them... i dunno if i want to go genuine as i don't like bending over for subaru...

[Soop]

It possible that the some added back pressure will increase bottom end torque. And there for can increase fuel economy a little. The change in bottom end torque could well be due to the ECU reset, the ECU will re-learn how you drive and make small adjustments as it goes along. I just did this today and the car drives a bit smoother. One other thing i suggest, is go and make sure your throttle body opens all the way. I found that mine was only opening to about 2/3 the way open. After adjusting it and taking the slack out out of the cable (Just enough so that the throttle body doesn't open, and not so much as to make the cable taught) the car feels much more responsive, and doesn't sound like an eighty year old emphysema sufferer at high revs.

[Blaeven]

It possible that the some added back pressure will increase bottom end torque. And there for can increase fuel economy a little.
The change in bottom end torque could well be due to the ECU reset, the ECU will re-learn how you drive and make small adjustments as it goes along.

I just did this today and the car drives a bit smoother.

One other thing i suggest, is go and make sure your throttle body opens all the way. I found that mine was only opening to about 2/3 the way open. After adjusting it and taking the slack out out of the cable (Just enough so that the throttle body doesn't open, and not so much as to make the cable taught) the car feels much more responsive, and doesn't sound like an eighty year old emphysema sufferer at high revs.

good idea...

also noticed that, with the new muffler, there seems to be more induction noise (though it could be that it just got drowned out by exhaust noise before)

it also goes 'ohhhhhh' when i let off between gear changes...

didn't notice that before...

might look into one of those 'datman' intakes that you're running paully.... comes highly recommended i'm sure...??

[Soop]

It works better than what you have at the moment. For what its worth my intake makes a wee "PUhshhhhhhh" sound when i get off the throttle quickly at high revs. Mick is a Member on here now, so PM Datman. His Business is called Techworkz, I can also get you his phone number if you wish.

[Blaeven]

It works better than what you have at the moment.
For what its worth my intake makes a wee "PUhshhhhhhh" sound when i get off the throttle quickly at high revs.
Mick is a Member on here now, so PM Datman. His Business is called Techworkz, I can also get you his phone number if you wish.

first... must save up money for it...

it's preeeeetty expensive at over $400...

think he could do it cheaper with mild steel or something...?

i'd probably get it painted/powdercoated/oxidised/whateverthehelltheydotomakethemblack anyway....

*shrug*

[Soop]

He could but wont. As far as he's concerned he'll use the best possible materials and have the best possible craftsmanship, and charge accordingly. If you can't afford it, then you don't get his stuff. Make's sense really. That's how one builds a reputation.

[Blaeven]

He could but wont.
As far as he's concerned he'll use the best possible materials and have the best possible craftsmanship, and charge accordingly. If you can't afford it, then you don't get his stuff.

Make's sense really. That's how one builds a reputation.

yeh, that is true...

well i'll just have to save up then...

and how do you make a piece of pipe black (other than spray paint).... is it called oxidising or something like that?!

[Soop]

Anodizing. They acid dip the metal and then put it straight into a chemical solution which causes a reaction with the acid. This reaction etches the metal and leaves a coloured residue. Its not particularly durable nor does it cover well. My preference would be painting or powder coating. If available electroplating may be a considered option as well.

[Blaeven]

Anodizing.

that's it....

My preference would be painting or powder coating.

if you get it powercoated can you get that bumpy paint job... where it's like covered in a sand like texture...??

[Soop]

Yes, that's called a "Hammertone" finnish. You can also have it glossy and smooth.

[Blaeven]

Yes, that's called a "Hammertone" finnish.

that's what i'll be getting then...

what's that kinda thing worth?