P38A 4.6 FAILED MOT due to CO emissions

Hello again!

Took the tractor for MOT inspection and it failed over CO emissions.
Got 6.5 when the limit is 4.5.
Replaced the air mass meter and the air filter, drove it for about 30Km on high revs. Tested again today, it only came down by 0.3, so now 6.2. HC level is ok.
Any ideas before I start pulling the coin out of my pocket? I'm pouring some injector cleaner and fuel additive and drive back home again on high revs today but I don't expect to drop (that much) enough to pass...

Is this goodbye?

o2 sensors as well ?

Tractor - as in Diesel powered??

Saint.V8 said:

Tractor - as in Diesel powered??

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That's what i thought. There is no CO2 test for diesels just a smoke test they don't produce a lot of CO2.

wammers said:

That's what i thought. There is no CO2 test for diesels just a smoke test they don't produce a lot of CO2.

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Is what I thought too....

This is another example of where more detailed information on the type/model and Model Year is important!

Saint.V8 said:

Is what I thought too....

This is another example of where more detailed information on the type/model and Model Year is important!

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Yep, your "Give us a hint" post should have been made titled in bold print locked as a sticky and not been writable on.

My bad... Sincere apologies!
4.6 V8, 2000.
BTW, here's the result of "high rev driving"...

As the emission should be controlled cia the ECU, it is time to think, filters, leads, plugs, fuel trim adaptions, fuel quality etc. then it would be time to think, valve stems/seals/seats etc....

Oil quality is another factor. Don't go changing parts without testing first. Ill wager you bought a cheap MAF that will throw everything out anyway.
Get some live data from the original MAF.

And I thought his thread title gave a huge clue to engine type, just saying

Oil service done last week.
Bosch air mass sensor.
Spark plugs and leads, possible... Tomorrow morning will test before I change anything else.

biketeacherdave said:

And I thought his thread title gave a huge clue to engine type, just saying

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And they were right! I edited the title...

Tilo said:

And they were right! I edited the title...

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That explains it

Do I need to reset the values when replacing the MAF? Or ECU does it on its own?
I read somewhere else this could be one of the reasons why the CO hasn't dropped after replacing the sensor.

Is this anyhow useful (or even reliable)?

This is the machine readings...

DOES IT HAPPEN TO HAVE LPG ?????????

mozz smith said:

DOES IT HAPPEN TO HAVE LPG ?????????

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No... Petrol's still very cheap here!

I'm worried by the maf reading. My maths make that 151kg / hr !!!
Heres some known good readings
Idle 680rpm - 22Kg
1200rpm - 32.5Kg
2000rpm - 55Kg
3000rpm - 92Kg

But then again, checking my maths its 15.2 kg hr - which is still out of scope on tickover.

No, im right first time 151 kg hr.
42 * 60 = 2520 grams a minute
2520 * 60 = 151200 grams an hour
151200 / 1000 = 151.2 kg / hr