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Lambda Sensor? Running Very Rich


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#1 WoodlandsMini

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Posted 06 June 2016 - 04:59 PM

Hi all,

 

Failed MOT today =/ running rich, spark plugs are covered in a sooty ash like deposit.

 

Tester said it should be about 3% but its closer to 20% ! ! !

 

The car has been off the road for a year, the previous owner reported that it would start, run until warm (around 20mins) then cut out... sometimes it would restart sometimes it wouldnt (I think this has been sorted - new fuel cut off switch) seems to have done the trick. I only mention this as it may be part of the issues.

 

Tried the simple things, vacuum hoses ect. but no such luck :(

 

Any suggestions? I'm guessing this would be the right one to replace or are there other options?

 

Thanks in advance :)


Edited by WoodlandsMini, 06 June 2016 - 05:00 PM.


#2 Fast Ivan

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Posted 06 June 2016 - 05:12 PM

its running rich (obviously), the reason why could be many things including the lambda, but could equally be the coolant sensor 

start with the service condition of the car, everything from the spark plug gaps, air filter, valve clearances, check all vac pipes/hoses - nothing but perfect condition, check all the sensors/connectors are clean and well seated, check the loom for signs of damage, pay attention to behind the air filter housing.

check all earths, including the loom earths

 

once all those basics are taken care of, and if the problem persists then we need to start looking at the sensors and their operation, do you have access to a code reader?



#3 WoodlandsMini

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Posted 06 June 2016 - 05:19 PM

No access to a code reader at present (quoted almost £100 just for someone to look!), air filter looks fairly new, but might replace for the sake of it, new plugs and gapped yesterday, no difference

Wiring is diabolical ! ! ! Part of the service history shows that one of the previous owners bought some sort of DIY wiring kit... we think the car has at some point had 3 immobilisers, still remanents of each!

Valve clearance has not been checked, think that may be next on the list, and whilst the hoses seem okay I may replace these again just to be sure :)



#4 humph

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Posted 06 June 2016 - 05:44 PM

I would suggest testing the supply to the lambda sensor with a voltmeter to see if it's getting power. The engine bay loom rubs at various points on the bodywork causing breaks in the wire. I had a similar problem which was traced to broken wire to the lambda so the car was overfuelling all the time.

 

There are instructions on testing the lambda online too.



#5 minifreek1

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Posted 06 June 2016 - 08:43 PM

I would suggest changing the CTS first as the same thing was happening on mine, I changed that and it stopped overfuelling almost immediately...

 

Also take a look at the inlet manifold to make sure it isn't blocked and stopping the CTS from getting hot enough and stopping it from working properly....



#6 WoodlandsMini

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Posted 06 June 2016 - 08:57 PM

Requested one from ECP today as a possible answer... will give that a try



#7 spiguy

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Posted 07 June 2016 - 11:54 AM

Does your water temp guage show the engine as hot when it is warmed up? If it shows cold on the guage, it could well be that the hoses / heated inlet manifold are blocked, so the CTS is not seeing hot coolant, which will mean the ECU will think the car is cold and continue to run it on the cold map. This will cause massive overfuelling. Easy enough to check, if you check the temperaure of the hose going to the manifold (after the take off on the heater hose) and it is not hot, then there is no flow there. Does the heater work? Could alternatively be that the heater take off on the thermostat housing is blocked, which would also mean no flow to the manifold / CTS.

 

If the pipe is hot and there is flow, but the guage reads cold, then maybe the CTS is faulty. Try to do as much diagnosis and head scratching as you can before going out and replacing parts as it can get expensive quickly.


Edited by spiguy, 07 June 2016 - 11:56 AM.


#8 FlyingScot

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Posted 07 June 2016 - 04:35 PM

Or find someone local with a code reader.... There's a pinned thread for folks willing to help


FS

#9 WoodlandsMini

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Posted 07 June 2016 - 05:06 PM

Does your water temp guage show the engine as hot when it is warmed up? If it shows cold on the guage, it could well be that the hoses / heated inlet manifold are blocked, so the CTS is not seeing hot coolant, which will mean the ECU will think the car is cold and continue to run it on the cold map. This will cause massive overfuelling. Easy enough to check, if you check the temperaure of the hose going to the manifold (after the take off on the heater hose) and it is not hot, then there is no flow there. Does the heater work? Could alternatively be that the heater take off on the thermostat housing is blocked, which would also mean no flow to the manifold / CTS.

 

If the pipe is hot and there is flow, but the guage reads cold, then maybe the CTS is faulty. Try to do as much diagnosis and head scratching as you can before going out and replacing parts as it can get expensive quickly.

Thanks will give that a try :)



#10 WoodlandsMini

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Posted 07 June 2016 - 05:06 PM

Or find someone local with a code reader.... There's a pinned thread for folks willing to help


FS

Will give this a go if no luck tomorrow, I have the afternoon off, so hopefully I can solve it without using a code reader, awesome thread though :D



#11 WoodlandsMini

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Posted 08 June 2016 - 06:48 PM

Update today, checked gauges, temp working and all hoses warm, heater fan doesn't work but pretty sure it would be warm.

Idle was a bit erratic so replace hoses with a rubber equivalent (not ideal) but it did improve the idle. We did spot that the purge valve had a damaged hose which has been replaced. Along with this the wiring that goes to the valve has been butchered at some point with 2 connections for the valve... I don't think this is right? But swapping over seemed to help

Don't know whether to take it back in for a retest or not, it seems improved... Either that or I'm high on car fumes!

#12 FlyingScot

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Posted 08 June 2016 - 10:04 PM

Which hoses did you replace with rubber? Not the vacuum I hope...

FS

#13 ryomini

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Posted 09 June 2016 - 01:27 AM

Hi there

I found 2 checks were essential when I had this problem

one - check and verify all vacuum hoses and rubber boots from top to bottom if happy move to number two

two - simply unplug the lambda in the engine bay just below the windscreen - the car will self adjust, if the car now runs good you know that your lambda is done and you will need 100 bucks and will probably have to remove the manifold as getting the old sensor out is the biggest pig in history - you may need a blow torch and 100 meter breaker bar - they are very happy where they are and insist on not coming out

 

I have been running my car for 2 years with lambda disconnected - I have to get the control done in 2 weeks, I am going to see if it passes without the sensor - if not I must also change that - like I said a right pig

all the best



#14 WoodlandsMini

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Posted 09 June 2016 - 12:19 PM

Which hoses did you replace with rubber? Not the vacuum I hope...

FS

I have...

 

The initial inspection showed that the hoses were okay... but closer inspection showed that someone had used a combination of rubber hoses that the smaller vacuum hoses go into..

 

You'll be happy to know that I do have the right part on order.. but was hoping this might just get me through MOT...

 

Happy to accept advice whether this would work, I used rubber as that is all I had... and no one locally has this.



#15 WoodlandsMini

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Posted 09 June 2016 - 12:20 PM

Hi there

I found 2 checks were essential when I had this problem

one - check and verify all vacuum hoses and rubber boots from top to bottom if happy move to number two

two - simply unplug the lambda in the engine bay just below the windscreen - the car will self adjust, if the car now runs good you know that your lambda is done and you will need 100 bucks and will probably have to remove the manifold as getting the old sensor out is the biggest pig in history - you may need a blow torch and 100 meter breaker bar - they are very happy where they are and insist on not coming out

 

I have been running my car for 2 years with lambda disconnected - I have to get the control done in 2 weeks, I am going to see if it passes without the sensor - if not I must also change that - like I said a right pig

all the best

Interesting suggestion ref 2. many people suggest testing with ACR2 ect. but never heard of just inplugging it... I guess you mean at the relay?






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