6 replies to this topic

[Rickmini]

Goodafternoon,

 

This is my first post on this forum and i while introduce myself. I am Rick and come frome the Netherlands, i own an Mini Cooper 1.3 SPI from 1992.

 

I few weeks ago the car was for MOT to the garage.  But was rejected because the CO was to high 0.8% the maximum is 0.5%.

To solve this problem, i made a cable and install MEMS FCR to diagnostic the sensor in the car. I saw that the value of the lamda sonde was stuk on 435mV, so i bought a new one.

 

The follow type = Bosch 0258003193. But with the new sensor the value are the same. I have inspect the cable loom, but it looks good.

 

Anyone an idea what the problem is? broken ECU?

ECU is type Rover MNE10027

 

The other problem is that the idle speed is to high 1100 rpm, is this related to an not working lamda sonde ?

 

 

Thank you.

Edited by Rickmini, 19 July 2022 - 04:40 PM.

[FlyingScot]

Hello Rick and welcome to TMF

 

It is unlikely that the ECU is broken.

 

Have a look on the pinned threads in this section and confirm that the vacuum pipes and fuel trap are in good order and replaced recently.

 

Air leaks or vacuum leaks are the most common source of high idle speed (this isn’t related to the lambda).

 

On your early Cooper Spi you may also have a throttle switch for the MEMS ECU to confirm idle position so if you have this please check the switch is working and the cable undamaged.

 

FS 

[R32Egor]

When you see the data in MEMS FCR - Is the car going into 'closed loop' mode when heated up and in idle??

Does the voltage for the Lambda sensor change at all? eg starts low and moves up to 435Mv or is it immediatly at 435mV? I seem to remeber that 435mV is a default when there is a fault with the Lambda sensor circuit.

Maybe somebody else can verify.

You can also test the Lambda sensor reading by using the method on the MEMSFCR.co.uk website - this helped me to find out that my Lambda sensor was actually working and other things were causing the problem.

But i also agree with above check all vacuum pipes are there sealed and working correctly.

Here is a pretty good video about the SPI vacuum tubes basics etc - was really helpful for me to learn the basics:-)

 

[Rickmini]

Thanks for the answers, i have check te vacuüm lines and it looks good. I have check the sensor by the trottle pedal, and repair it. Now if the engine is cold the rpm is 1100 and with an warm engine is around 800 rpm. So that is good. The value of the lamda sensor is immediately at 435 mv. If i do the test with the method on memsfcr the values are not changing. I have change the lambdasonde but the values is still at 435 mv.

[R32Egor]

The lambda sensor needs to have the casing earthed for it to work.

When i was investigating mine I basically took the Lambda sensor out of the exhaust and then connected it like normal and then placed the outside touching the earth strap at the engine steady.

The reading should drop or be very low (as theres lots of oxygen).

 

If this does nothing and still reads 435mV and its a new sensor then must be a problem with the wiring to the ECU or the ECU it's self.

[genpop]

Hi, you got a new lambda sensor.  So it should be easy to take it out again. Connect it to the loom and somewhere to earth.Switch on ignition.Now the sensor should become worm.If not theres a fault in the loom,the ecu or the new sensor itself.Make the same test with your old sensor.

[R32Egor]

Ah yeah - i forgot about the heating test also