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Their a different type of O2 sensor ?

Do they not detect air fuel ratios and report them back to the computer ?

So how is having them straight out if the turbo not better then having them half way down the exhaust, if feeding signal to ECU and not just a gauge for you to look at ?

For the sack of this gauge it wouldn't matter where it was positioned, if only one sensor for a twin turbo setup then in the merge would be a good place for it, twin sensors then just before the merge, far enough up it so you don't get gases from the other turbo passing sensor

For my intended use for the O2 sensors is to feed the signal back to the ECU as my ECU will compensate from the signal so the closer to the engine the better for me, I would rather pay the difference in money to have better quality sensors that will bolt in to and are happy to be in the factory location then buy cheaper sensor and have to try and mount then near the end if the front pipe

Don't you have to run these Bosch sensors in the collector just before the cat or they are inaccurate. I think they need to be at least 20cm from the turbo. I will probably weld the bung in the collector, could have one in each front pipe as XKLABA suggested. Might see if I can use the shift light as a lean warning light too. See how I go.

Oh yeah that's one of the articles I read....20 inches was the consensus with most wideband kits.. not 20cm like I mentioned..sorry for the inaccuracy.

Their a different type of O2 sensor ?

Do they not detect air fuel ratios and report them back to the computer ?

So how is having them straight out if the turbo not better then having them half way down the exhaust, if feeding signal to ECU and not just a gauge for you to look at ?

For the sack of this gauge it wouldn't matter where it was positioned, if only one sensor for a twin turbo setup then in the merge would be a good place for it, twin sensors then just before the merge, far enough up it so you don't get gases from the other turbo passing sensor

For my intended use for the O2 sensors is to feed the signal back to the ECU as my ECU will compensate from the signal so the closer to the engine the better for me, I would rather pay the difference in money to have better quality sensors that will bolt in to and are happy to be in the factory location then buy cheaper sensor and have to try and mount then near the end if the front pipe

You talking about the factory narrow band vs a wide band?

They are are different type of sensor.....

Anyway, I'm sure if I could be bother ed I could work out the time it takes for the exhaust to travel a meter inside your exhaust pipe at say 4000rpm, but I'm so sure it would be such a miniscule amount of time it wouldn't matter to anyone.

Being able to put the sensor into the factory location is slightly helpful for mounting it, but ad far as accuracy and speed goes I don't think there would be any noticeable difference in wither location.

The factory narrow band sensor is closer as it has to be warmed up by the exhaust. Not for accuracy.

FWIW when I tested my wideband (in the cat housing just before the mesh) vs the Dyno's one at Chequered tuning, there was literally no difference in what they were reading, so the difference between the Cat and the exhaust pipes at the back of the car is near-zero.

  • Like 1

If you have a functional cat, then the O2 signal should be at least a little different after the cat than before it. One of the major tasks of a cat converter is to reduce NOx back to N2 and O2. So even if you are running rich, and therefore there is effectively no O2 in the pre-cat gas stream, the ratio between unburnt fuel and O2 will change across the cat.

Of course, if your cat is dead or otherwise ineffective (100 cell cat anyone?) then it probably won't matter so much.

Because the difference is so small it has no real impact on the tune, the tunner will have a ballpark ratio he will be aiming for and, then it's a matter of listening for knock whist increasing the timing.

  • Like 1

I have always wondered why not use it after the cat because given that a cat removes some impurities wouldn't the sensor run cleaner?

I have run my wideband with the sensor after the cat. Sent the readings all over the place, particularly light throttle would jump around like it was on a pogo stick. Moved the sensor infront or the cat and it was sweet.

Because right after the cat is too hot I would imagine. By the exhaust tip it has cooled down enough, and will only read a little leaner, which means the engine is a little richer. No big deal.

  • 2 months later...

Well just an update>

Did the install and very impressed with the unit so far.

Bit of mucking around with the relay wiring and seeing that the rear seats were out I ran a 4G wire from the negative terminal to the engine bay and ran the main earths to it.

Mounted the gauge to the dash just above the wiper stalk and the solenoid and map sensor in the engine bay.

Did all the programming through the gauge and it was the easiest menu system I have ever seen.

Did the free air calibration for the o2 sensor just a matter of switching the ignition with the sensor disconnected and waiting for the prompt, then plugged it back in and powered the unit and the cal was performed, the plugged it into the exhaust...done.

Then set up the boost cut to 20psi until i put it on the dyno not that you really need to dyno it. And set 100% cut which means it cuts to sping pressure or 9psi.

Then set the spring pressure to 9psi, They recommend 1-2 psi below the actuator spring pressure to prevent boost spikes.

Then set the boost cut at afr so I set 10psi at 12.9 afr. What it does is if boost is above 10psi and afr is12.9 or more then the the boost will be cut to spring pressure (9 psi).

Slowing increased the duty cycle to achieve about 18 psi.

Didnt play with the gain yet.

Driving around for a week or so and works very well. Dispay is nice and clear and when solenoid is working it dispays the duty cycle. Noticed instantly that there was a qicker build up of boost at about the 6-12 psi range probably due to the actuator remaining closed.

So now going to run the 5V output to the ecu and program it to cut ignition if it goes lean, also set up a warning LED on the gauge that gets triggered by the ecu.

Interesting to note to is that the unit has triggered a boost cut a couple of times at about 15psi at wot, So what happens is that the boost drops to 9psi and then builds back up. Suprisingly gently too. So I will see what happens on the dyno and then have a look at the ecu log.

Again just played with the settings as I was not really interested in getting it spot on, just wanted to make sure it did what it was meant to do and so far very impressed.

Edited by XGTRX
  • Like 1
  • 5 months later...

Hows the SCG-1 unit going? Also does the peak hold function holds both max afr and boost readings at the same time?

I am quite interested in getting this as I want an afr gauge, an electronic boost controller and a better boost gauge. (R34 MFD is only displaying the boost in kpa/bar and only up to 2 bar)

But I actually have a haltech platinum pro ecu and can probably just wired up some gauges to display the info without extra sensors... so I just wanna see if its worth it haha.

Hows the SCG-1 unit going? Also does the peak hold function holds both max afr and boost readings at the same time?

As above I am very impressed with the unit. Sorry not sure what you mean by this but if you are asking if it holds boost right up to the shift point, yes it does and if it drops off you can manage it by adjusting the gain function. Please explain further if I didn't answer this correctly. Thanks mate.

As above I am very impressed with the unit. Sorry not sure what you mean by this but if you are asking if it holds boost right up to the shift point, yes it does and if it drops off you can manage it by adjusting the gain function. Please explain further if I didn't answer this correctly. Thanks mate.

Thanks for the reply!

hmm with the peak hold function, you can look back and see what the highest boost was after a run. (the gauge holds the peak record of the boost)

does it only work for the boost? or both boost and afr?

The only logging it has is in the log works program on a pc. You can log while you are connected to a notebook and save the data for review. It will plot a graph over time or rpm (x axis) of boost and afr (y axis). When you hover the mouse over a point it will give you the value summary. Hope this helps.

  • 4 years later...
3 hours ago, elle76 said:

Any uppdates about how the SCG-1 has performed these years? Looking to buy one for my carburetor turbo build as the main boost controller. Anything to think about before buying one?

/ a random Swede.

 

 

It's a good unit, does everything it claims well.

Good boost control, good boost cut in a lean condition, good logging and a 5v output for ECU integration.

No complaints.

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