WideBand O2 Sensor Placement?
 

I'm planning to purchase an Innovative Motorsport LM-1 WideBand Meter (with RPM kit) for my car and was wondering where the best place to position the O2 sensor is.

The OEM 930 Muffler doesn't have an O2 bung on the muffler's inlet, so I assume the factory put the O2 sensor before the turbocharger, correct?

Why would one choose to put the sensor post turbo, instead of pre-turbo like the factory did?

Discuss please?

I have an Innovate Motorsports LC-1 wideband, in the documentation it says:


On Turbo Charged vehicles:

Install the bung downstream from the turbo before the catalytic converter. The high exhaust pressure before the turbo interferes with the lambda measurement and the high exhaust temperatures encountered there can damage the sensor"

Yupp. It's a heated sensor so you can install it any place you like. Installing it too near the exhaust pipe end will give artificialy high AFR readings on idle, as gases are blown out in puffs and there will be certain degree of flow reversal when revs are low.

So best point is just downstream fromm turbo.

So, just after the turbo, before the exhaust gases enter the muffler, correct?

Everywhere after turbo is OK, except near end-pipe where it risks taking whifs of fresh air on idle. Muffler is probably OK too, it'll just react little slower.

Yeh, well it seems everyone is putting them just after the turbo, before the muffler.

mines just after (4 or 5 inches) after the turbo Merv. The LM1 o2 sensor cable is just long enough to reach the front of the passenger seat, if routed from muffler up and under the oil filter and through the firewall behind the pass side shock tower.

hey Merv,good move on the wideband.On my car l only have a few inches of pipe between the turbo and the muffler so l mounted mine right after the muffler body.The tailpipe has some length to it after the bung so the readings are accurate.l got this muffler from a Porsche speed shop specializing in turbo conversions and that`s where they had put the bung.Too close to the turbo and the life expectancy of the sensor goes down dramatically.

On my straight pipe, my bung is ~6" after the turbo. And it is very accurate. On my Borla muffler, I mounted it after the muffler (not enough room between turbo & muffler inlet). And it reads accurate only off idle. It will read 20% or O2 only at idle.

Thanks for the feedback, fellas.

So, I take it mounting it just before the muffler, on an OEM 930 Euro Muffler is too close to the turbo, right?

The tail-pipe is quite long on these OEM mufflers, so I may just have the bung welded just after the muffler. I have the twin-pipe style muffler.

Point the sensor down, wire up. Condesation during warm up apparently messes with them. I was told this is why all the manufactureres install them probe down.

Jim

I'm in a bit of a dilemma and need some advice :confused:

Is it worth buying the LM-1 if the piggy-back ECU I have has logging capabilities of A/F ratio against the RPM and load ranges?

The only advantage (I see) of getting the LM-1 is logging capabilities, but if the ECU has logging built in AND can accept a wideband input, then is it better to just get the LC-1 Wideband Controller instead?

Here's the link to the LC-1!

If ECU can accept WBO2 and logs RPM, MAP and AFR then it's no point to buy LM1 as you can use Autotune-capability. Just make sure that ECU supports WBO2 and check if you need external interface in order to use it (most ECU I know don't support WBO2 nativly but need some sort of box interface that outputs 0-5V voltage or so).

lc has a little button on the gauge to record, and doesn't come with an RPM converter. The LC looks more complicated to rig up, and wouldn't be something you'd carry around and use on another car.
If all you want is a WB gauge and have something else to log with then I think it's the best deal out there. I've had both kits in my hands, and the lc1 is very nice. I'm finding that the more I drive the more I just check afr's after I change something. I would like an afr gauge, but more often I'm looking at fuel pressure and boost.

Thanks all... what length cable comes with the LC-1 kit? Is it long enough to reach under the passenger seat (drivers seat in USA vehicles)?

I think I will go with the LC-1. The MAP-ECU I have supports the LC-1 and so will the new standalone ECU I'm planning to buy/install at a later date ;)

I thought you were talking about the xd16 the one with the gauge, sorry about that. I know the lc1 and the lm1 cables aren't long enough to reach the dash.

Merv,
I'm not sure on the Innovative, however I'm using a WMS brand.
http://www.wmsracing.com/o2/index.htm
on an 87 with a 3.2, O2 sensor is in the stock O2 sensor location before the CAT. Cable just about reaches the center console. Interface from the WMS provides the narrow band to the ECU, and the WMS has very simple AFR and RPM output through a serial port , atypical laptop. Their software is simple. Support is very good, and as I recall you could either cut and splice their wires if you wanted to extend them. The advantage of their product is the small foot print. The disadvantage is the foot print or display is not atypical round gauge.

Hi,

The LC-1 serial cables (to reach the XD-16) can be extended to up to 30 feet. Should be long enough for even a stretch limo version of a 911. :D

Regards,
Klaus

Sorry, I was referring to the Sensor wire. I think InnoMotorsports only supplies them with a 6ft sensor cable, which isn't long enough and will have to be manually extended! It's pretty disappointing they don't supply them pre-made at any length desired :(

Hi,

The sensor cable for the LM-1 is 10 feet. There is an optional 18 foot cable also.
There is really no sensor cable for the LC-1, as the sensor plugs directly into it and the LC-1 module is designed to live outside in the open (waterproof). It doesn't need to be inside in the passenger compartment.
The length of the sensor cable itself as attached to the sensor comes like that from Bosch. Those cables should not and cannot be extended as the sensor breathes its outside O2 refereence through the cable insulation.

Regards,
Klaus