Technical Single Turbo O2 sensor install and data

veer90

Captain
Nov 16, 2016
1,000
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West Nyack, NY
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e90 335i 6MT
Thought I'd make a thread to collect some data on O2 sensor options for the single turbo peeps. As everyone knows, 2-bank fueling logic forces ST kits to place the pre-cat O2s in the manifold between the head and turbine, exposing them to extremely harsh high temperature and positive pressure environment which shortens sensor life significantly.

Every manifold and turbo combination is different in terms of how harsh they are on sensors which is why I created this thread. If you have a manifold that eats O2 sensors for breakfast, there are a few options to choose from. You can switch to a different brand of sensor better able to take the heat (NTK, ADV, Denso, etc.) or the sensor life can be extended with the use of spacers, shims, and/or venturi heat sinks (see post below).

Note: most manufacturers have two PNs for N54 pre-cat O2 sensors, since the wiring harness are 2 different lengths on the OEM twin setup. The connectors and sensors are otherwise identical. Either PN can be used as long as the sensors are connected to the correct bank on the engine wiring harness.

I've prepared a table outlining results from my personal testing. Others feel free to reply to this thread and I'll update table accordingly.

Brand:
PN:
Mileage on ST:
Boost/Fuel:
Heat Sinks (Y/N):
Manifold:
Turbo:
Notes (if any):

BrandPNMileage on STBoost / FuelHeat Sinks (Y/N)ManifoldTurboNotes
Bosch (OEM)17098
17102
<50026 psi / E85NDoc RacePTE 6266 Gen280k mile old sensors. Cooked in one night of tuning pulls (~20). Car was allowed to cool down between pulls
Bosch (OEM)17098
17102
<20N/A did not even hit boostNDoc RacePTE 6266 Gen2Temperature/function codes and dead sensors out of the box
NTK24322
24345
7,55333 psi / E85YDoc RacePTE 6266 Gen2Sensor was accidentally damaged and needed replacement. was running strong prior to damage
NTK24345
24345
3,20935 psi / E85YDoc RacePTE 6266 Gen2Started throwing SES light on high boost multiple gear street pulls. gradually worsened to low boost multi gear pulls also.
Denso2345139
2345139
2528 psi / E85YDoc RacePTE 6266 Gen2Testing in progress
NTK24322 243454,00028 psi / E85YDoc RacePTE 6466 Gen2N/A
OEM17098
17102
35,00028 psi / E85NJPGTW 3884 OEM sensors with 113k miles re-used for ST install
 
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veer90

Captain
Nov 16, 2016
1,000
762
25
West Nyack, NY
Ride
e90 335i 6MT
Shims and Heat Sinks

If you switched to a different brand of sensor and still have issues with them getting too hot, it's worth considering shims and/or heat sinks if your manifold doesn't already have them. Some manifolds incorporate heat sinks, to varying degrees of effectiveness.

Our O2 sensors are 18mm diameter threads, which means you need 18mm ID shims. These stainless washers from McMaster worked well for me:
Pulling the sensor tip out of the exhaust stream a bit helps, but you can't go too crazy as you only have so much thread to work with, and if the sensor is too far out the DME becomes unhappy with the response time and throws codes.

If shimming the sensor is ineffective, you need to install heat sinks. I've had very good resuls with the Innovate Motorsports 3729 HBX-1:

3729 HBX-1.PNG


These mount the sensor out of direct exhaust flow and pull gases to and from the sensor tip with machined internal passages that work off a venturi pressure differential. AFRs, fuel trims, and sensor response times are unaffected.

When installing these heat sinks it's important to index them properly. The side port must be indexed pointing into the exhaust flow, i.e. the hex face with the indentation must be as close to perpendicular to the manifold tubing as possible while facing away from the turbo. This is where those 0.1mm thick washers come in, as the HBX-1 are not supplied with indexing shims.

hbx-1 indexing.PNG


I redid my install on the heat sinks this weekend using one 1.5mm thick washer and as many 0.1mm washers as needed for proper indexing. Thus I pulled the heat sink out of the exhaust tubing by an additional ~1.7-1.9mm without affecting sensor response. Procedure as follows:
  1. Apply anti-seize to heat sink threads (VERY light coating as to not contaminate internal passages. O2 sensor internals do not like anti-seize).
  2. Install one 1.5mm thick washer and predetermined amount of 0.1mm thick washers on heat sink for correct indexing (trial and error).
  3. Install heat sink with washers onto manifold and tighten to 70 ft-lb. Repeat for bank 2.
  4. Install O2 sensors into heat sinks and tighten 1/4 turn past hand tight.
I went tight on the heat sinks and looser on the sensors to avoid the heat sinks coming off with the sensors which happened to me in the past a few times. Use common sense with torque values here - no need to crank heat sinks to the moon, just enough to prevent this issue from occurring. Sensors of course need to be tight enough to seal and not come loose with vibration.
 
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nademdurani

New Member
Jan 29, 2019
3
2
0
Ride
2010 BMW 335i
Thought I'd make a thread to collect some data on O2 sensor options for the single turbo peeps. As everyone knows, 2-bank fueling logic forces ST kits to place the pre-cat O2s in the manifold between the head and turbine, exposing them to extremely harsh high temperature and positive pressure environment which shortens sensor life significantly.

Every manifold and turbo combination is different in terms of how harsh they are on sensors which is why I created this thread. If you have a manifold that eats O2 sensors for breakfast, there are a few options to choose from. You can switch to a different brand of sensor better able to take the heat (NTK, ADV, Denso, etc.) or the sensor life can be extended with the use of spacers, shims, and/or venturi heat sinks (see post below).

Note: most manufacturers have two PNs for N54 pre-cat O2 sensors, since the wiring harness are 2 different lengths on the OEM twin setup. The connectors and sensors are otherwise identical. Either PN can be used as long as the sensors are connected to the correct bank on the engine wiring harness.

I've prepared a table outlining results from my personal testing. Others feel free to reply to this thread and I'll update table accordingly.

Brand:
PN:
Mileage on ST:
Boost/Fuel:
Heat Sinks (Y/N):
Manifold:
Turbo:
Notes (if any):

BrandPNMileage on STBoost / FuelHeat Sinks (Y/N)ManifoldTurboNotes
Bosch (OEM)17098
17102
<50026 psi / E85NDoc RacePTE 6266 Gen280k mile old sensors. Cooked in one night of tuning pulls (~20). Car was allowed to cool down between pulls
Bosch (OEM)17098
17102
<500N/A did not even hit boostNDoc RacePTE 6266 Gen2Temperature/function codes and dead sensors out of the box
NTK24322
24345
7,55333 psi / E85YDoc RacePTE 6266 Gen2Sensor was accidentally damaged and needed replacement. was running strong prior to damage
NTK24345
24345
3,20935 psi / E85YDoc RacePTE 6266 Gen2Started throwing SES light on high boost multiple gear street pulls. gradually worsened to low boost multi gear pulls also.
Denso2345139
2345139
2523 psi / E85YDoc RacePTE 6266 Gen2Testing in progress
Brand: NTK
PN: 24322 / 24345
Mileage on ST: 4k
Boost/Fuel: 28 psi/ Full E85
Heat Sinks (Y/N): Y
Manifold: Doc Race
Turbo: PTE 6466 Gen 2 1.00 A/R
 
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Jewgo

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Nov 6, 2018
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Great thread. Once I get some miles on my speedtech kit with NTK I can provide some data too!
 

Torgus

Major
Nov 6, 2016
1,745
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0
Boston
Ride
ACF 6466 E92 + METH
Brand: ADV
PN: ???
Mileage on ST: 10k
Boost/Fuel: 23 psi 93 + 1200 cc 100% meth
Heat Sinks (Y/N): N
Manifold: ACF FTW!
Turbo: Precision 6466 Gen 2 1.00 A/R
Notes (if any): They are sold out online and have been for a while. When they fail I will probably switch to NTK unless Motiv gives me a deal on new ones. $450 for o2s is a bit cray cray. Motiv did do my tune and incorporated it into the file so I don't have to click the box in MHD. Not that it should have any affect on their longevity that I am aware of.

Thanks for starting this thread!

How the hell did OEMs last 30k for someone?
 
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Scorpstan

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Feb 27, 2017
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what we need are ADV pre Turbo sensors.
speedtech have one for a good price:
 

Milan

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Dec 24, 2016
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what we need are ADV pre Turbo sensors.
speedtech have one for a good price:


Bro stop posting this shit. We all tried them 4 years ago and 80% of us had problems. It’s well documented on basically every forum that exists for this platform.
 
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Scorpstan

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Feb 27, 2017
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Bro stop posting this shit. We all tried them 4 years ago and 80% of us had problems. It’s well documented on basically every forum that exists for this platform.

Bro. I tested by my self 1 year many kind of sensors. And all of them before results in trims and afr differences at high power and speed level. Maybe you got 4 year ago the wrong advs, fail install, wrong tables or did just pulls to 130mph, I don't know. What I can tell you that since I have the Bosch pre turbo ADV´s my afr and trims runs perfectly in a pull from 0 to 300kph with 950hp.
So do what you want. I post just my experience.
 
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Milan

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Dec 24, 2016
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Bro. I tested by my self 1 year many kind of sensors. And all of them before results in trims and afr differences at high power and speed level. Maybe you got 4 year ago the wrong advs, fail install, wrong tables or did just pulls to 130mph, I don't know. What I can tell you that since I have the Bosch pre turbo ADV´s my afr and trims runs perfectly in a pull from 0 to 300kph with 950hp.
So do what you want. I post just my experience.

Let me ask you this. Why doesn’t Motiv sell them anymore? Why aren’t they on every single turbo car out there?

The thing is, most people who “had luck” with their ADV sensors were comparing them to sensors that needed replacement.

This community is full of fads. There was a time where someone was hyping up Autolite GTR plugs as the be all end all. Good luck finding anyone running those now, like the ADVs most of us had problems.
 

Scorpstan

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Feb 27, 2017
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The thing is, most people who “had luck” with their ADV sensors were comparing them to sensors that needed replacement.

I tested last Week 2 New ntks and this Week the advs. You can see the Logs in the other o2 sensor thread. Both with back pressure tables. The ntks works ok but not so good like the advs. Why. Because the adv have a special design for pre turbo installation. The ntks will result in false afr reading at long wots and the afrs ands trims will go in big difference to each other. End of the game is that the sensors switch off and car go in openloop. Pic below->
 

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Milan

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Dec 24, 2016
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That’s funny because aside from constant lambda codes, most of us (including myself on two different cars) had the same results with the ADVs. Trims getting stuck, car in open loop, etc.

Some of us had Chris swap out sensors on the regular.

I personally made it 15k on NTKs. I think best case I made it 500 miles with ADVs.
 

TheAudioGuy

New Member
Nov 1, 2020
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Hi guys I was thinking today, if the exhaust gasses are far to hot for the o2 sensors then why not use a egr cooler that can be cooled via the cars cooling system, then either run it inline with the collector 3-1 spout out into the egr then past the 02 sensor then back to the collector at the turbo flang
930BDD41-9FAD-425D-BF8C-44E430043CA4.png
 
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TheAudioGuy

New Member
Nov 1, 2020
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I do know there’s two sensors before anyone says 🤣 but there are some really small egr coolers for 1.3 to 1.4 Diesel engines so I think it could be doable, what do people think 🤔
 

Milan

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Dec 24, 2016
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I do know there’s two sensors before anyone says 🤣 but there are some really small egr coolers for 1.3 to 1.4 Diesel engines so I think it could be doable, what do people think 🤔

No point. The innovate heat sink works really well