33 replies to this topic

[RaLF020]

So when I bought my SPi last summer it was running rich. So rich that it was spitting black soot out the exhaust! I investigated and found the vacuum hose from the air box to the inlet manifold had a broken elbow and had become detached. I fixed that that and it seemed to idle slower (about 900 where it had been 1200 even when warm) and the amount of soot out the back seemed a lot less.

Anyway, I took it for to MOT this week and it failed BIG TIME! readings off the scale...
Fast Idle Test:
CO 12.963%
HC 1503
Lambda 0.64
taken with oil temp at 82 degrees

Reading the other threads on SPI emission failures, I checked my vac pipes again and found the yellow one on the top of the Air box was off - Doh! Problem is, I can't believe that these readings are caused by that hose which seems to only control where the air gets in from (warm off the engine or cold from the front of the car). Can anyone enlighten me?

I also tested my lambda sensor (as per the pinned topic - thanks Sproket). The lambda reads 900mv all the time. I don't see it alternate low/high. When I pinch the fuel feed hose it drops to 300mv but it seems to stay high until a second or 2 after the engine nearly stalls - is this correct?

I'm thinking I'm gonna need a new Cat but don't want to replace it until I have got the engine running clean. I can't believe the Cat alone will bring the readings in so there must be something else going on - any ideas?

Thanks,
RaLF

[charie t]

vacuum hoses can make a lot of difference, it tells the ecu what load the engine is under, if it cant read anything it assumes its under full load
Making sure the pipes are on is one job, make sure they are all clear and not leaking or melted

Edited by charie t, 06 April 2012 - 07:13 PM.

[mini-luke]

What does your temperature gauge read like?

[Sprocket]

There is something fundamentally wrong somewhere for it to be running that rich. the 12% CO is representative of the 0.64 lambda and the hydrocrbons are so high as the fuel just isnt burning becaus there is so much of it in the cylinder. Spark plugs will be jet black and there will be black sooty expultions from the exhaust, you might even be able to see black smoke.

You have already proved that the lambda sesnor functions, so for now, discount that.

Coolant temp snsor? Check the temp gauge at least reaches the mid way line. Air temp sesnor connected? Incorrect reading on MAP sensor? All of these can easiy be checked with a diagnostic, or be difficult to check without. Make sure you have tried everything in the pinned topics first, give the engine a good service and don't drive it untill you have fixed it, otherwise the cat will overheat, melt and choke the engine, if it hasn't alrady.

[RaLF020]

Sproket. A choked engine? that sounds serious. Would that mean needing to de-coke the cylinders (or worse)....?

The temp guage reads mid way and the engine seems to get to temp quite quickly.

You're right about the spark plugs & black sooty expultions from the exhaust but I don't really get black smoke.

Thanks.

[charie t]

Sproket. A choked engine? that sounds serious. Would that mean needing to de-coke the cylinders (or worse)....?

The temp guage reads mid way and the engine seems to get to temp quite quickly.

You're right about the spark plugs & black sooty expultions from the exhaust but I don't really get black smoke.

Thanks.

choked just means restricted power due to blocked exhaust
decoke would not be necessary, running rich will cause the plugs to be black
i've had several come to me with this problem, even as bad as idling made number plate on mine go black. and all have been a blocked/split/melted/disconnected vac pipes, after I have tested all the sensors.

[RaLF020]

There is something fundamentally wrong somewhere for it to be running that rich. the 12% CO is representative of the 0.64 lambda and the hydrocrbons are so high as the fuel just isnt burning becaus there is so much of it in the cylinder. Spark plugs will be jet black and there will be black sooty expultions from the exhaust, you might even be able to see black smoke.

You have already proved that the lambda sesnor functions, so for now, discount that.

Coolant temp snsor? Check the temp gauge at least reaches the mid way line. Air temp sesnor connected? Incorrect reading on MAP sensor? All of these can easiy be checked with a diagnostic, or be difficult to check without. Make sure you have tried everything in the pinned topics first, give the engine a good service and don't drive it untill you have fixed it, otherwise the cat will overheat, melt and choke the engine, if it hasn't alrady.

So it's taken a month but having read all the pinned topics and a number of other posts relating to emmissions on the I carried out the following...

- Replaced all the MAP hoses from the inlet manifold to the fuel trap, ECU and Air cleaner.
- Took out the ECU and sat it on the tank in the airing cupboard for a couple of days to dry out the MAP sensor (not sure if it is possible to remove the actual sensor but I couldn't get the main PCB out to access the sensor)
- Replaced the Coolant Temp sensor
- Replaced the Oxygen sensor (couldn't get the old one out so had to replkacy the exhaust mainifold too)
- Replaced the CAT
- Serviced the engine (oil, filter, new plugs)
- Checked the air temp sensor by seeing that the cold/hot air induction valve oporates
- Removed and tested the termostat, drained a refilled the coolant.

With all that done I took the car back for an emmissions retest. HC and Lambda are now in spec but the CO is still reading too high:
I didn't get a print out but the values for a fast idle test were about:
CO about 1.1
HC about 150
Lambda around 1.0

The engine is running smooth and steady on both idle and with load and is fine on the overun. There is the odd small and faint popping noise when it runs at idle but nothing too noticeable.

Any ideas what is keeping the CO high? If the answer is get it on a diagnostic then I am a bit stuck as my efforts to find someone with one (who knows enought to use it properly) have drawn a blank.

Any suggetsions would be approeciated.

[icklemini]

ummm would be good to see the live data from a diag machine to make sure all is reading as it should be...

The replacement cat a good one?

was it good and hot for the test? (a good spirited drive before the test to 'clear it out')

Edited by icklemini, 05 May 2012 - 05:00 PM.

[RaLF020]

ummm would be good to see the live data from a diag machine to make sure all is reading as it should be...

The replacement cat a good one?

was it good and hot for the test? (a good spirited drive before the test to 'clear it out')

The CAT is brand new (standard minispares item) and since the car does not have a valid MOT it's not easy to give it a good run before the test, so while the engine was cirtainly up to temperature I can't be so sure about the CAT. It's only a 3 mile drive to the garage but the car was idling for a good 20 minson top of the drive there.

[icklemini]

ok, well I think a longer trip to the MOT station is needed! - technically there is no distance requirements to get to a MOT station

Temp gauge on the dash is in the middle yesh?

[RaLF020]

Yep, Temp gauge reads midway. Was just above mid when the MOT was done.

[RaLF020]

Since the last emissions test I cleaned out the MAP senor with cotton (on a hot radiator for 24 hrs) and replaced the dizzy cap, rotor and leads. I then took it for a 30 minute 'spirited drive' on the way to the test station so the CAT was nice and hot. But readings are still failing...

Natural idle:
C0 - 0.6
HC - 1280
Lamda - 1.03

Fast Idle:
CO - 0.8% (fail)
HC - 150 (pass)
Lambda - 1.01 (pass)

If my understanding is correct the fast idle lambda reading suggests a good AFR of 14.8 (just on the lean side). The HC was way up during natural idle but came down slowly to under 200 after a good few minutes of running the engine at 3000rpm. Does this put a question mark over the CAT???? The CO is also quite high but with the Lambda reading being good, does this suggest the CAT is not doing what it should? Is it even possible to have a bad CAT? (remember mine is brand new) - It is, after all a passive device!

A local guy wants £75 to come to me to do a 'full diagnostic'. Says he has done all Rover cars with MEMS but is not a mini spcialist. Does that sound a bit steep?

Any other ideas would be appreciated because i'm starting to loose the will with this issue.

Edited by RaLF020, 16 May 2012 - 04:56 PM.

[Bartje]

The "funny" thing with SPI's is: the ECU has the capability to detect a fault (faulty temp sensor for instance), and switches to "Limp home mode" by taking a predetermined value for that sensor (in case of the CTS, that's 60 degrees), so it's possible to keep driving the car.
Most modern systems/cars will notify you with a "check engine" light of some sort, but I guess that was something Rover decided to save money on back in those days.
Most modern systems/cars (including the MPi) will do a systems check on every starting sequence, and when the earlier fault was solved, it'll continue running with that former faulty sensor.

The SPi does NOT ! It will keep the fault saved in it's memory forever, UNLESS somebody clears the faults from the ECU's memory. Taking the battery off will only reset it's learned idlespeed and steppermotorsetting, nothing more, nothing less. Even storing it in the attic for 10 years doesn't clear the stored faults !

Afaik, the Lambdasensor and the crank sensor are excluded, and will continue to work after replacing, but if your CTS has stored a fault in the ECU's memory, it will always think the engine is running at 60 degrees, which will result in a faulty mixture, and faulty CO.

So.. let somebody reset the stored faults in the ECU (I can do that for you, but I'm in Holland, not very convenient :s) especially when this fault is related to the CTS!

Edited by Bartje, 16 May 2012 - 11:27 PM.

[RaLF020]

The "funny" thing with SPI's is: the ECU has the capability to detect a fault (faulty temp sensor for instance), and switches to "Limp home mode" by taking a predetermined value for that sensor (in case of the CTS, that's 60 degrees), so it's possible to keep driving the car.
Most modern systems/cars will notify you with a "check engine" light of some sort, but I guess that was something Rover decided to save money on back in those days.
Most modern systems/cars (including the MPi) will do a systems check on every starting sequence, and when the earlier fault was solved, it'll continue running with that former faulty sensor.

The SPi does NOT ! It will keep the fault saved in it's memory forever, UNLESS somebody clears the faults from the ECU's memory. Taking the battery off will only reset it's learned idlespeed and steppermotorsetting, nothing more, nothing less. Even storing it in the attic for 10 years doesn't clear the stored faults !

Afaik, the Lambdasensor and the crank sensor are excluded, and will continue to work after replacing, but if your CTS has stored a fault in the ECU's memory, it will always think the engine is running at 60 degrees, which will result in a faulty mixture, and faulty CO.

So.. let somebody reset the stored faults in the ECU (I can do that for you, but I'm in Holland, not very convenient :s) especially when this fault is related to the CTS!

That's very interesting - thanks. Having replaced just about everything I was considering that something i replaced must have been an OOB faulty item but your explanation might answer why all my work has not resulted in a complete fix. I replaced the CST really only as a precaution and because it was cheap and it was easy to do while I had the inlet manifold off, but the first set of emissions figures were so far off the scale it may well have been faulty in addition to the split MAP pipe, clogged Lambda sensor and old CAT.

I haved read quite a bit about the MEMS system and the ECU but not having first hand experience seeing the ECU diag reader in use it's hard to get your head around.

I'll see if I can get it done cheaper than £75 though. If anyone knows someone with a reader in the Hants/Surrey boarder area please let me know.
Thanks again!

[Bartje]

Bring it to the IMM in Hungary, I'll reset it for you.. ;)