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Code Reader - Faulty Sensor Question


Best Answer Pee , 30 June 2020 - 12:20 PM

Just to close of this thread, Replaced Lambda, Air Temp and Coolant sensor, Vac lines all replaced with silicone versons giving a much better fit and piece of mine due to less joints via the previous elbows.  Reassembled and reset the codes via the USB reader dongle thingy and its all good! - Fuel smell while driving has gone, appears to run much better but might all be in my head!  :shifty:

 

Thanks for your help guys.

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#1 Pee

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Posted 20 June 2020 - 05:31 PM

Hey, 

I've got a 94 SPi which I've owned for 20 years, I usually tax it during the summer months put a few hundred miles on it then its tucked away for another year, it runs fine but i've always thought it was fairly rich, after a brief drive the cabin would smell of petrol and your clothes stink all day but maybe I keep forgetting this is the joy of a mini? Anyway I recently purchased a diag cable after it was recommended on this forum (ebay + android app), It reported back a faulty coolant, air inlet and map sensor which may account for the rich running however the figures the app gives out appear to be correct so could these be old fault codes that have never been cleared, is that how the MEMS system works? I've not replaced these in the years i've owned the car so maybe it is a true fault.

 

Images from reader attached, if anything looks odd with the figures id love to know what you think.

 

Cheers all and glad this community is still going.

 

Pete

 

 

 

Attached Files



#2 FlyingScot

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Posted 21 June 2020 - 11:09 AM

Clearing the faults should remove them from storage in MEMS. If they re-appear it seems that they are live faults. Thats the way most code readers work with MEMS (I have only stand alone systems not the one you describe).

 

FS



#3 Ado1379

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Posted 22 June 2020 - 07:48 PM

Looking at the first picture the live readings seem to show faults. It’s staring ‘true’ on all 3 sensors and the time stamp was June 19 14:18. However, the likelihood that all 3 sensors have gone is usually minimal. But as you have stated that you have owned the car for 20 years and never replaced them would make me think twice.
If it was me. I’d clear the fault codes and try again. If they persist, I’d pick the cheapest sensor to buy, replace it and then use the code reader again. If it doesn’t change the status for that sensor then you may very well have a wiring issue.

#4 Ado1379

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Posted 22 June 2020 - 08:04 PM

The interesting thing is, the temperature readings are showing ‘reasonable’ figures. If temp sensors are faulty they usually show either a negative figure or a ridiculously high positive figure, because they work on resistance and if they are open circuit then there’s no resistance.

On second thought, unplug the MAP sensor (as it’s probably the easiest to get to) then run the fault codes again. If it changes then you know the fault code reader is doing its job and then it is the sensor.

#5 Pee

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Posted 23 June 2020 - 06:11 PM

Yeah the figures look OK which made me wonder if a reset was all that was needed but it does smell rich, am unsure if the ecu thinking there is a fault would then cause it to ignore the readings and assume default values. Either way I've decided to replace the sensors due to it being around 18 years since they were last done according to my stack of receipts and for some reasons I was in the mood to remove the whole inlet to clean it all up.

MAP sensor is confusing me, on an spi where is it?! Thought it was in the ecu hence the importance of the vac pipes.

Edited by Pee, 23 June 2020 - 06:13 PM.


#6 Ado1379

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Posted 24 June 2020 - 11:45 AM

I think it is in the ECU. Forgive me it’s been a few years since I’ve had an SPI. I was talking about the one on the air filter, I think that’s air temp?

I think if you have the manifold off you’d be silly not to replace the coolant sensor

Edited by Ado1379, 24 June 2020 - 11:46 AM.


#7 FlyingScot

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Posted 24 June 2020 - 02:06 PM

MAP is in the MEMS ECU as your were thinking (vac pipes). It's soldered onto the main PCB and has a plastic nipple which exits on the middle of the casing where the electrical connections are.

 

FS



#8 Pee

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Posted 24 June 2020 - 08:02 PM

I think it is in the ECU. Forgive me it’s been a few years since I’ve had an SPI. I was talking about the one on the air filter, I think that’s air temp?

I think if you have the manifold off you’d be silly not to replace the coolant sensor

 

Yeah thats the plan, its been a while so i'll treat it to some fresh sensors all round, however my mini has a habbit of developing new issues when you try and treat it nicely!

 

thanks for clarification on the MAP sensor FS. 

 

Pete



#9 Pee

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Posted 30 June 2020 - 12:20 PM   Best Answer

Just to close of this thread, Replaced Lambda, Air Temp and Coolant sensor, Vac lines all replaced with silicone versons giving a much better fit and piece of mine due to less joints via the previous elbows.  Reassembled and reset the codes via the USB reader dongle thingy and its all good! - Fuel smell while driving has gone, appears to run much better but might all be in my head!  :shifty:

 

Thanks for your help guys.






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