27 replies to this topic

[Tony H]

Failed mot on emissions this morning wondering where I start working it out.

Car been sat in the garage for 2 years so maybe should have given it a thrash before the mot.

It's supercharged. Have full tullet 2.5inch exhaust.

Pic of the test readout attached.

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[Johnboyhgt]

Looks like there is no catalyst fitted ??

 

[Tony H]

Its got the normal tullet cat for the 2.5inch

[smiley]

Can you inspect it? (would not be the first tullett cat to fail on an SC)

 

[Tony H]

OK what is the easiest way to do that?

 

I take it from the replies the numbers are well out and an italian tune up wont cut it. 

[hairy]

Your CO levels are very high. Are your lambda sensors OK?

[Tony H]

How do I check?

 

It idles and runs ok, no eml.

[Arno]

Looking at the calculated lambda value from the MOT gas analyzer at around 0.8 lambda  it's idling and fast-idle at around 12:1 AFR.

 

Aka. Running pig-rich. Cat has no hope in hell to clean that up

 

Possibly dying/slow primary lambda throwing off the feedback and keeping it from getting to stochiometric 14.7:1 for the cat to work.

 

Rad fan is not running constantly? Which could indicate the ECU is in failsafe mode.

 

Bye, Arno.

[Tony H]

Fan not on no.

 

How can I test the primary lambda?

 

Can problems on the intake also cause this?

[Johnboyhgt]

Drop the three 13mm bolts out before it goes into the u bend. visual inspection of the catalyst.

[hairy]

 

How can I test the primary lambda?

 

 

Can you do a temporary swap with someone local?
 

[Tony H]

Have not had time to look at the cat or anything yet but I plugged in my reader "obdlink mx" there were no fault codes. It is possible to get any useful info out of the obd port? These are the info it shows with engine at idle....

 

 

 

 

[Dan r]

I'm in the middle of the same problem with mine, same spec. just fitted new cat, new lambda still high CO, my next check is for an exhaust leak upstream of the lambda. Just waiting to borrow an exhaust leak test kit as its not very easy to do by eye!

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[ICD]

My MOT guy leaves the car running for a good 20 - 30minutes before doing the emissions whilst he does all the other checks.

 

get the temprature  up and ensure the fans are running so you know the temp is high

 

Never failed..close, but never failed

[speedster norway]

Test lambda.
1: In live data meny on your obd scanner watch your number 1 lambda sensor,and it must switch once a second between 0,1 and 0,8 volt

2: If it does now watch the second (2) lambda sensor .With hot engine and RPM at 3000 for about 3 min,and the sensor should be fixed at 0,6Volt approx.If it move like lambda 1,this confirms a faulty cat.

3:If the second sensor (lambda) reads either 0,1 volt steady or 0,8 volt steady the fault is elsewhere.


The engine have to be in closed loop and hot
 

[hairy]

I'm in the middle of the same problem with mine, same spec. just fitted new cat, new lambda still high CO, my next check is for an exhaust leak upstream of the lambda. Just waiting to borrow an exhaust leak test kit as its not very easy to do by eye!

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Stick a bung in the tailpipe(s) and see if it stops the engine.
 

[Dan r]

Going to use one of these

https://www.amazon.c...b_qzkGFbYMWGYFH

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[Tony H]

Test lambda.
1: In live data meny on your obd scanner watch your number 1 lambda sensor,and it must switch once a second between 0,1 and 0,8 volt

2: If it does now watch the second (2) lambda sensor .With hot engine and RPM at 3000 for about 3 min,and the sensor should be fixed at 0,6Volt approx.If it move like lambda 1,this confirms a faulty cat.

3:If the second sensor (lambda) reads either 0,1 volt steady or 0,8 volt steady the fault is elsewhere.


The engine have to be in closed loop and hot
 

 

At idle>

 

Primary lambda cycling between ~0.025v and ~0.6v

Secondary lambda cycling between ~0.06v and 0.9v

Fuel trim cycling 0% and -6%

 

 

3000 RPM>

 

Primary lambda steady ~0.05v

Secondary lambda steady ~0.9v

Fuel trim steady +10%

[Dan r]

Just did a leak test and the flange between manifold and downpipe which is apparently not meant to need a gasket is leaking a lot, its done up well so will need a gasket. Must have warped a bit somehow as never had issues before.
Once a gasket is fitted I'll report back with CO results.

If you haven't got access to a smoke test you could gently pressurise the exhaust and squirt bubble mixture over the joint.

Does anyone know a part number for a gasket that fits the tullet 2.5 inch system?

Don't want to use any paste or silicone up stream of lambda.

Thanks
Dan

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[oakmere]

Use high temp sensor safe RTV if you can’t get a gasket that fits.