02 relay ?

[Noslin]

does the 02 sensor need to have (or should it have) a relay? been reading a bit trying to find information on whether it should or should not. it seems factory cars have relays for the 02's. also, for wiring, it appears they are hooking the Heater + to the relay?

this would be for a five wire Bosch LSU 4.9 02 sensor.

ty
dean

[sardengineering]

Good day,

The heater circuit for lambda sensors should be wired to auxiliary outputs on the M84 and not through a relay. The auxiliary function parameter with the ECU Manager software is 9. As advised by the help file within the ECU Manager software, AUX 1 0r 2 should be used for heater circuit support for lambda sensors, however, if these outputs are in use you may use any of the other available outputs. I have found it to be time saving if a mock up your calibration file was to be created based on the configuration of your engine ahead of time so that you can deduce the allocation of outputs relative to advisories of PWM speed support. With respect to lambda sensor support you should be able to use the following sensor types listed below, however, I would strongly advise that the sensor you intend on using be sourced for your MoTeC dealer or directly for the nearest MoTeC office.

Bosch LSU 4.0
Bosch LSU 4.2
Bosch LSU 4.9
NTK

I hope this has given you the clarity you need to proceed, cheers!

[Noslin]

thank you for your reply, im confused then. according to the Product Data Sheet 57006 for your Bosch sensor it shows the ground being controlled by an Aux and the power going to same power as ecu (A26). so your saying the power for the o2 sensor should be controlled by Aux then?

i did not see a Product Data Sheet for the 02 sensor that states it is for the M84 so i used Product Data Sheet 57006.

here is how mine is hooked up

pin
1=B26
2=B16
3=A18 (AUX 1 - OPTION 9)
4=A26
5= N/A
6=B25

ty
dean

[sardengineering]

Hello Dean,

My apologies for the delayed response, I've been away from my desk for most of the working day. From reading through your post it appears that my response may have been confusing indeed. You see the heater circuit can't be run on a relay in the sense that it can't be always on or always off. Or, to put it another way, the heater circuit can't be operated by a relays switching on and off as slowly as a relay functions. Instead, the heater circuit has to be controlled on a frequency basis and to achieve this a PWM circuit is needed. According to Bosch Motorsport the heater control frequency for the lambda sensor should be ≥ 100 Hz, hence the advisory for which auxiliary output should be used.

So you're actually correct if I have understood you clearly. I suppose you could use a relay purely from a theoretical stand point but it would be both unnecessary and impractical. With the heater circuit using direct battery voltage and the auxiliary output on the M84 (correctly configured within the ECU Manager of course) you should have the intended functionality, no problems.

Sorry for the miscommunication. I misunderstood your comment about the use of relay to mean a permanent 12 volt closed circuit operation, so always on. And in reflection, my explanation about the implemented use of the auxiliary output was intended to be understood as the PWM control of the heater circuit itself; not the power source for the circuit.

I sure hope this gives you the clarification and verification being requested. If anything isn't clear or you need elaboration to any extent please feel free to send a follow up request and I will try my best to answer you appropriately.

Thanks for choosing the MoTeC brand, cheers!

[Scott@FP]

Heater - is the output that is controlled by the ECU when the ECU is set up with a wideband using La control, this output grounds the heater coil to produce the heat, and a target heat is being maintained depending on sensor type. Heater + can also be set up on say the ign or inj B+ relay or separate fuse if desired. When you set up the La sensor to type 'normal' the heater - does not turn on until after a time period of the engine running. If set to 'fast heat' the heater - is turned on whenever the ECU is active. 'fast heat' mode can be detrimental to some sensors by forcing condensation dew/moisture to be boiled off by the heater element rather than exhaust gasses.

While it is not strictly necessary to use a relay or fuse to provide B+ to heater +, it may be desirable to do so.

[SprinterTRD]

The +12V supply to the sensor should originate from the same supply +12V as the ECU A26 pin.

As long as the +12v to the sensor is off when the +12V to the ECU is off it will be OK.

The heater negative should go to a ECU output pin so the ECU can maintain the lambda sensors temperature.

Its that simple! The MoTeC drawings show it this way.

[Noslin]

Thank you everyone for your input.
This is on my drag car. I have the o2 positive connected to a fuse panel that sees power when main shut off switch is turned on. Power was being applied to the sensor at all times. I think the 02 was cycling causing feedback into the system.

I will attach the o2 sensor power to the coil/fuel pump relay so the 02 will have power when it is supposed to and not all the time.


Thank you
Dean

[stevieturbo]

Thank you everyone for your input.
This is on my drag car. I have the o2 positive connected to a fuse panel that sees power when main shut off switch is turned on. Power was being applied to the sensor at all times. I think the 02 was cycling causing feedback into the system.

I will attach the o2 sensor power to the coil/fuel pump relay so the 02 will have power when it is supposed to and not all the time.


Thank you
Dean

The sensor will only be powered when it has both 12v and ground.

As the ecu provides this ground, it will only see a complete circuit when the ecu allows it. Hence no need for relays etc.

But it would also do no harm to add a relay.