Lambda fail on M800

[Merlin]

I have M800 with DBW and dual lambda and every other feature enable on rotary engine

So Have Bosch 4.9 LSU sensors as
lambda 1 in front rotor
Lambda 2 in rear rotor
Sensors in mode 8 fast heat as I always run them for setting warm up fueling

Sensors are about 2 years old
Lambda 2 gives c5 error and no reading

Ok time for new sensors
Plug 2 new ones in and go to do air cal
Continuous C5 error ... Will not cal up

Plug in old sensors same result ...C5 both sensors

100% check of wiring .... Remember these worked for 2 years

Figure damaged aux outputs. .. Swap to spare ign outputs ....same result ..C5

Ok set up one of my PLM ...... All 4 sensors cal up and work fine .....by now I'm peaking a bit

Ok set up another M800 with my file and plug in ..... Same result C5
I can see the output duty cycle go to about 80% then bang C5

Put cal numbers in from PLM .... Same no reading C5 error


I can only put this down to a software error ...
Any thoughts people's

John P

[Merlin]

The fun Continues


After being told it must be a wiring fault
I replaced both Lambda sensor looms ....SAME FAULT...ahhhhhh

so after looking at My PDM Lambda 12v output I see it never has any current load .....

I then load a fresh file into my ecu with NO DBW and wire sensor heater control to AUX 1 and 2 .....BOOM all working fine

I am NOW 100% CONVINCED this is a ecu software issue

John P

[David Ferguson]

So DBW control only works with AUX1 (and uses AUX2). What Aux outputs were your Lambda's connected to with your DBW config, and how were they wired?

Have you looked at the Auxiliary Output Characteristics in the Help Topics. Only AUX 1 & AuX2 can drive high-sides at 5A.

Are your Lambda heaters wired for low-side control? Aux1 & Aux2 current limit instead of shutting down like other outputs if the maximum current is exceeded -- I bet you are hitting that.

Have you considered using a solid-state relay if you have them wired high-side and need to connect them to Aux5 - Aux8. Or using the relay and wiring them low-side to any available Aux Output. This could eliminate the current limit shutdowns.

Since your problem seems to be related to the config, perhaps you could post that (or a copy with your ignition & fuel tables zero'ed if you feel that is proprietary ).

[GWRMOTORSPORT]

Hi Merlin

we get this quite often when we're commissioning an M*00,
the trick is to warm up the sensors with a heat gun, carefully!
You should find the lambda error cycles from C6 down to C1 a few times and then
a real lambda value should appear

Hope this helps
Regards

Steve
GWR Motorsport
UK

[Merlin]

Hi David
My responses are below

So DBW control only works with AUX1 (and uses AUX2). What Aux outputs were your Lambda's connected to with your DBW config, and how were they wired?
When the DBW was in Aux1 and 2 I have had the Lambda control in Aux 3 and 4 ...then Aux 7 and 8
...and even into Ign 5 and 6...none of those worked

12v + comes from PDM
12v - into ECU AUX programed as Control channel

Have you looked at the Auxiliary Output Characteristics in the Help Topics. Only AUX 1 & AuX2 can drive high-sides at 5A. Yes I do Know that ....But the software says to use other Inputs when AUX1 and 2 are DBW

Are your Lambda heaters wired for low-side control? Aux1 & Aux2 current limit instead of shutting down like other outputs if the maximum current is exceeded -- I bet you are hitting that. Im sure this is What is happening . On Intinal heat up the PDM peaks at about 5 amps for a very short time ..less than 1 sec..then settles back to 3.6 amps

Have you considered using a solid-state relay if you have them wired high-side and need to connect them to Aux5 - Aux8. Or using the relay and wiring them low-side to any available Aux Output. This could eliminate the current limit shutdowns.Yes I could use two to get correct control ...I will suggest this to MoTeC when I call them

Since your problem seems to be related to the config, perhaps you could post that (or a copy with your ignition & fuel tables zero'ed if you feel that is proprietary ).I do Tune and Supply engines to a Number of Rotary racers In Aust ..so I do not think its in My Best commercial interest to post my Configs for the world to see ...Nothing Personal Just Protecting what Myself and My customers have spent our money on
I am the First in Aus to Have a 13B with Quad Throttles and DBW

[Merlin]

Hi Merlin

we get this quite often when we're commissioning an M*00,
the trick is to warm up the sensors with a heat gun, carefully!
You should find the lambda error cycles from C6 down to C1 a few times and then
a real lambda value should appear

Hope this helps
Regards

Steve
GWR Motorsport
UK

Hi Steve

I can get the same result by shorting the control (12v-) wire to ground ..But this does not put the sensor in the correct heat range and will therefore not read correctly ....I have tried both scenarios ...and get totally different Cal numbers during Air cal function ...so I think that could be engine suicide

thanks for the input

John P

[SprinterTRD]

Wire the lambda heater into a unused injector output configured to Lambda heater control.

This will resolve the current issues when the sensor is cold.

[Merlin]

Wire the lambda heater into a unused injector output configured to Lambda heater control.

This will resolve the current issues when the sensor is cold.

I have to admit it did not try the Inj outputs
The software says it's not recomended
But at this stage I will give it a go

John P

[SprinterTRD]

The only issue is there is no over current protection on the injector output, so if you short +12V to the LA- heater wire , you will damage the ECU.