Technical Single Turbo O2 sensor install and data

[nyt]

how much boost do you have. i saw with other speedtech setups that till 30-32 psi there is no problem. (ADV backpressure 35 max.)

It may have started after bringing the boost up above 30psi or so, but happens even at 20psi now. Also, bank 1 and 2 were off by about 0.8, with bank 2 reading lean. When I pulled my plugs, bank 1 was clearly running lean and bank 2 was not. Have new sensors on the way. Are you still running the ADV? Are you happy with them still?

 

[Scorpstan]

if they get damaged one time than its over.
on 30psi they should work.

yes still on advs. this time with bigger AR and less boost (30psi) same HP level. testing Phase will be in mai. waiting for my 6hp28 Adapter.

 

[dubgtr]

Are all these results with Docrace manifolds for their Top Mount mani? If so, does anyone have info on how well the log style bottom mount manifolds do with those sensors? I'm installing a bottom mount kit this weekend (or about as much as I can finish) and I plan on installing new NTK sensors, mostly because NGK has always been good to me, and after working at a vw dealer for 5 years, Bosch left a bad taste in my mouth. Oh and because of the lack of a need for new calibration data. I'm interested to know how many are using log mani's. Mine has heat syncs installed and where the bung attaches to the manifold the hole drilled in the mani is actually smaller than the bung. I'm thinking it will limit some of the direct flow from the exhaust ports and the o2 will get whatever gas happens to flow up through the hole.

 

[rac]

Are all these results with Docrace manifolds for their Top Mount mani? If so, does anyone have info on how well the log style bottom mount manifolds do with those sensors? I'm installing a bottom mount kit this weekend (or about as much as I can finish) and I plan on installing new NTK sensors, mostly because NGK has always been good to me, and after working at a vw dealer for 5 years, Bosch left a bad taste in my mouth. Oh and because of the lack of a need for new calibration data. I'm interested to know how many are using log mani's. Mine has heat syncs installed and where the bung attaches to the manifold the hole drilled in the mani is actually smaller than the bung. I'm thinking it will limit some of the direct flow from the exhaust ports and the o2 will get whatever gas happens to flow up through the hole.

if the system is dead ended there might not be any flow up to your sensor, you will not get very good afr readings if the gas their stays stagnant.
you would be relying on good turbulence to get that gas turned over - i hope the hole is not too small and your not set back too far. if i understand your set up correctly.

 

[nyt]

My issues don't seem sensor related. I've captured some logs where it goes open loop before sensor leans out. Something is just disabling bank 1, and not sure what.

 

[rac]

My issues don't seem sensor related. I've captured some logs where it goes open loop before sensor leans out. Something is just disabling bank 1, and not sure what.

is this happening on start up? the dme does start up checks bank to bank on afr response, if it doesnt like what it sees it throws the banks that it thinks has an issue into open loop.

i cant recall all of the incidents as i had so many teething issues, googling my own username and open loop i found this: https://www.n54tech.com/forums/showthread.php?t=51137

anyway point being there's a good chance that the sensor is not reporting what the dme expects either because the amount of fuel or the returned afr is not matching what it expects and then goes into open loop. that's a safety mechanism such that closed loop fueling based on dodgy information doesnt spiral the actual afr in the wrong direction.

 

[nyt]

is this happening on start up? the dme does start up checks bank to bank on afr response, if it doesnt like what it sees it throws the banks that it thinks has an issue into open loop.

i cant recall all of the incidents as i had so many teething issues, googling my own username and open loop i found this: https://www.n54tech.com/forums/showthread.php?t=51137

anyway point being there's a good chance that the sensor is not reporting what the dme expects either because the amount of fuel or the returned afr is not matching what it expects and then goes into open loop. that's a safety mechanism such that closed loop fueling based on dodgy information doesnt spiral the actual afr in the wrong direction.

No, under load it kills bank 1. The greater the load and higher the rpm, the more likely it is.

 

[dubgtr]

if the system is dead ended there might not be any flow up to your sensor, you will not get very good afr readings if the gas their stays stagnant.
you would be relying on good turbulence to get that gas turned over - i hope the hole is not too small and your not set back too far. if i understand your set up correctly.

If you imagine a hole about an inch in diameter, then about an inch down from that hole there is a hole about a half inch in diameter. Thats what it looks like, actual sizes aside.

 

[NicL]

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):

Brand	PN	Mileage on ST	Boost / Fuel	Heat Sinks (Y/N)	Manifold	Turbo	Notes
Bosch (OEM)	17098 17102	<500	26 psi / E85	N	Doc Race	PTE 6266 Gen2	80k mile old sensors. Cooked in one night of tuning pulls (~20). Car was allowed to cool down between pulls
Bosch (OEM)	17098 17102	<20	N/A did not even hit boost	N	Doc Race	PTE 6266 Gen2	Temperature/function codes and dead sensors out of the box
NTK	24322 24345	7,553	33 psi / E85	Y	Doc Race	PTE 6266 Gen2	Sensor was accidentally damaged and needed replacement. was running strong prior to damage
NTK	24345 24345	3,209	35 psi / E85	Y	Doc Race	PTE 6266 Gen2	Started throwing SES light on high boost multiple gear street pulls. gradually worsened to low boost multi gear pulls also.
Denso	2345139 2345139	25	28 psi / E85	Y	Doc Race	PTE 6266 Gen2	Testing in progress
NTK	24322 24345	4,000	28 psi / E85	Y	Doc Race	PTE 6466 Gen2	N/A
OEM	17098 17102	35,000	28 psi / E85	N	JP	GTW 3884	OEM sensors with 113k miles re-used for ST install

Hi there. I find this post very helpful. I have gone to a single turbo setup and tried my best to follow literature which suggest that the o2 sensors for both banks should be place in the dump pipe so thats what I did. The problem now is that one bank seems to be pulling fuel and the other adding fuel. Is this the incorrect setup?

 

[odesh]

Hi there. I find this post very helpful. I have gone to a single turbo setup and tried my best to follow literature which suggest that the o2 sensors for both banks should be place in the dump pipe so thats what I did. The problem now is that one bank seems to be pulling fuel and the other adding fuel. Is this the incorrect setup?

Do you mean that you have installed both pre-cat O2-sensors on downpipe and still using two bank fueling? In that case both banks will get the mixture of data from both banks. In worst scenario, you can make other bank super lean and DME can't detect it, since both O2-sensors get good mixture when in reality other bank is lean and other is rich.

You can't really run setup like that with dual bank fueling. Either have both sensors on manifold or use single bank fueling and install one O2 on the downpipe.

Correct me if I'm wrong tho.