Gtr Conundrum

[jeffworld2]

Hi all

My gtr will start but not accelerate if you connect both o2 sensors. If hot and i reconnect everything is fine. If i disconnect one (either) it will start and run ok when cold. I have been driving around with just the rear connected.

Does the rb26 ecu use one when the other is unplugged or does it just skip closed loop all together?

Is there a fault with one of these or am i just not going into cold start enrichment and should be looking at temp sensors or idle control

[Moodles2]

With Nistune anyway, the default setting for the RB26 basemap with O2 feedback is 30C (the minimum temperature which the ECU will use O2 sensor readings) so I'm guessing the stock ECU has the same behavior. You really need a CONSULT cable to see what both sensors are outputting when cold, and hot, will also help to see what the ECU thinks the coolant temperature is.

Are you sure you have the right O2 sensors? BNR32 ecus expect titania sensors and wont work very well (or work at all) with zirconia sensors.

I have 2 sensors in my GTR, one is a Bosch the other is NTK (both titania). The NTK one tends to report 0v while cold (still warming up) while the Bosch one seems to report 0.4-0.6v straight away so the ECU would try to trim fuel while still cold. With O2 feedback defaulted at 30 it would run sluggish until the coolant temp was over 55C so I changed O2 feedback to 70C in Nistune and it's been running smooth since.

[jeffworld2]

i do have consult but my laptop is dead, which makes it a bit tricky.

At normal running temp the coolant is 83degrees, but i havent checked it when cold.

The o2 sensors were swinging, but i'm only seeing one value representing both on the software i was using. can you recommend some software?

It's a factory ecu but i was planning to go nistune as its past its limits as is. should i get it running as best i can or would nistune solve this issue properly?

[jeffworld2]

o2 sensors are 3 wire.

should i grab an r33 gtr ecu to check? it's actually a 33 motor anyway

[Moodles2]

Titania and Zirconia can both be 3 wire. Zirconia will have 2 white wires (heater) and 1 black wire (signal) while a Titania sensor will have a black wire (reference), red wire (reference + heater) and a white wire (heater): http://www.lambdasensor.com/main/mcolours1.htm

Are you using a R32 ECU with a R33 motor? If so R33 GTR ecus wont work with titania sensors, and R32 GTR ecus wont work with zirconia sensors.

I like ECUTalk, it's free (and will show seperate values for both sensors): http://ecutalk.com/ecutalk.aspx

[jeffworld2]

Thanks for your help.

Trouble is, i'm not really sure how to tell if its an r32 or r33 gtr ecu, and i wasn't really sure how to check the sensor type as they don't have z or t on the code.

I will have to research these and figure it out. seems like its probably the issue though.

[Moodles2]

ECUTalk will report the ECU part number, just a matter of google'ing that part number.

[jeffworld2]

Have put an r32 gtr ecu in after confirming the 26 loom is from a 32, and the o2 sensors are with a red wire, so the motor is a r33 with 32 gtr loom and bnr32 o2 sensors.

It was running on an bnr33 ecu and was idling smoothly, but up and down between 1000 and 1500 rpm. Now with the r32 ecu it snaps down to 1000 and is dead flat.

nice.

For reference:

How to tell the difference between a 32 gtr and 33 gtr loom: The plugs under the dash end will suit the car models. also on a 32 o2 sensors should earth without the ecu connected while 33 will open circuit.

How to tell the difference between titania and zirconia oxygen sensors: Anything with a red wire is probably the r32 gtr type.

How to tell the difference between r33 gtr ecu's: R33 is 24u on the code, r32 is 05u