how to fool ecu that lambda sensor is there

[shiny boy]

HI Guys

this is all on a ME7 C70 with an OBX 3" decat exhaust

I have fitted an Innovate AFR meter. I took out the second Lambda sensor ( Narrow band ) and installed the Innovate Wide band one.

I used the innovate substitute analog narrow band output and connected this to the black wire going back to the ECU.
I also used the white +12ve that fed the original sensor and used that for the power supply for the Innovate AFR.
I could not use the other white for the heater earth as this is not a true earth and brought up a fault on the Innovate gauge so used a full chassis earth.
As Far as I could see there was no use for the grey system earth on the new system so I insulated that as well
Now I am Getting a P0036 HO25 heater controll circuit fault and a CEL

The Innovate Gauge works fine all I need to do, Is fool the ECU into thinking that the heater circuit is still connected.

Does anybody know how to do this without doing the bodge of tying up the original sensor under the car

Any Help will be gratefully recieved

[crankie]

why are you doing this

[Clan]

the Lambda heater circuit needs to see the correct resistance , you are feeding your sensor with it so the current flowing wont be the same as the heater circuit , hence the fault code .

[shiny boy]

Hi,

Crankie, I am fitting the AFR Gauge, it now works correctly but I need to lose the CEL and the P0036 fault code.

Clan, Thanks but I understand that part of the problem what I don't know is what Resistance or what current drain does the ECU want to see to eliminate the P0036 Code as the heater circuit is a simple wire coil it must be possible to simulate it without having another O2 take off bung welded into my new exhaust.

once this is acheived I can then program the analog output of the Innovate AFR to make the ECU see what ever I want

Best Regards

[Clan]

Its variable , resistance when cold is a few ohms but quite a bit more when hot , whether the ECU is sensitive enough to know the difference between hot and cold resistance i dont know , easy for you to test on your car though . it might be as simple as adding a 3 ohm 20 w resistor in the heater circuit .( and use it to heat your wash bottle :-)

[shiny boy]

Hi Clan,

I was thinking along the same lines myself, the only thing that has given me thought to pause is experimenting with the ECU inputs could be very, very expensive if one were to **** it up.
I was hoping that somebody had already successfully sorted it, with the amount of us, enterprising chaps trying to make volvos break the sound barrier i would have expected it to be almost run of the mill I know the boys in their Evo's and Impretza's have been mucking about with these sort of projects almost since the days the cars first turned a wheel.
I am trying to puzzle out a safe way to experiment on the car as I can't afford to screw it up after spending 4 grand modifying it ( hence the reason for the AFR gauge in the first place)

Regards

[BlackBeast]

Still don't understand the reason for doing this.

It would have been so much easier with less faffing about to use a spacer for the 2nd lambda sensor, drill a hole in the correct place on the outer curve of the downpipe and weld a boss on for the wideband sensor.

The reason why the boys in their Volvo's don't do it is because there is absolutely no need.

[shiny boy]

Hi Blackbeast,

as far as I can see it there is very little difference in where I put the Innovate sensor it does not need to be up on the top on the outside of the bend, It reads just fine where it is.
Why put a spacer on the original narrowband I don't see why it needs it there were no codes thrown up by it.
all you are saying is leave it in circiut and out of the way, which is back to the bodge of Boy racers.
i can't believe that is a fix !!!!!!!!!!!

[crankie]

Originally Posted by crankie

why are you doing this

thanks i dident know what an afr guage was iv looked it up and i now im a bit wiser, thought you was doing all this just to get rid of the lambda sensor,im not into tuning in my day it was carbs and timing

[marka101]

Just a quick tip, lambda sensor spacer is made very thin maybe 1mm
mine broke fitting it using no more than a few nM , so brought another
and tightned very lightly , fault has not come back but early days only done 70miles fitted to my v70 2007 t5 expolice , up on ramps used 22mm spanner
easy to got to took maybe 5 mins to swap for £5 worth a try .
hope this helps someone