Diagnose more V6 emissions? (CO,but Lambda seems fine) DON'T DELETE

[Mrs Feynmans Bongos]

Howdy all,
My V6 has just failed MoT emissions: "Exhaust carbon monoxide content after 2nd fast idle exceeds default limits [8.2.1.2(b)]"

I'd hugely appreciate any advice the lovely gurus here can offer, by way of clues/methods to suggest to my mechanic?
(it's booked in for 17/8, not a Bongo specialist but content for me to source parts even perhaps in advance, depending of level of certainty )

Here's the readout


It was "warm" after 20 miles to work +same back, both ways held in 3rd for 10 miles, with plenty of "Redex" in the tank. New cat 2018 from AutoJap.
Given HC and Lambda both passed, MoT garage said no point trying their "BG 44k" fuel system cleaner (this helped last year after it failed while ~cold)

Strong smell of petrol from the exhaust led them to suggest looking for failing INJECTORS.
(Eg by reading-out the ECU. Mechanic told me he can try but would expect no codes without a dashboard warning light)

PS I've read recent thread Emissions Diagnostics on V6 but mine looks different, Lambda being fine.

[Winnie-bongo]

I can't help but will point out if your Bongo is pre September 2002 it should have a non cat test for the MOT as the DVSA have confirmed. I know you want to get it running right

[Mrs Feynmans Bongos]

Thanks, very interesting ...

Presumably this also applies to 1st use ABROAD before 2002, even with a **factory-fitted catalytic converter**? (My V6 is 1999, was actually owned by Mazda Corp, only imported in 2013)

Can you give me a name/date from the DVSA please?
(My MoT garage will want to check this out carefully)

My emissions readout states max limits "200 ppm Vol", "0.3% Vol", for HC and CO respectively.
If you are saying the limits should actually have been 1200 ppm, 3.5% respectively, it seems it should have PASSED!

Whereas if readout would in fact quote 3.5% limit as "0.35", then my CO readings 0.645, 0.618 still FAIL.

[Bongolia]

Here is a link
https://www.gov.uk/guidance/mot-inspect ... 8-nuisance
Drop down the screen to the flow charts,there is also text relating to personal imports and first use.

This link will give you a pdf of the current emmisions book refered to in the testers manual look in here for your vehicle it will give you the manufacturers emmisions data if its listed.

https://assets.publishing.service.gov.u ... dition.pdf

Yours would seem to be the 3.50 co as it is not a passenger vehicle.
Personally if you are running emmisions as tested I wouldnt be looking to improve on that.Was a time when .50 co was OK and as your lambda is pretty much there I wouldnt be poking about.

[Winnie-bongo]

Yes as all Bongo's and Freda's are imports and have cats as standard but as they were made with more than 5 passenger seats they are not classified as a passenger car by DVSA
There is a PDF on it here
https://m.facebook.com/groups/252905573 ... 6136245733

[Doone]

I've added this post to the FAQs for future reference.

[Mrs Feynmans Bongos]

I told my MoT garage the result of my cry for help here, that basically because it was manufactured pre-2002 with 8 seats, it classes as a "non-passenger vehicle" for emissions and, because it is not listed in DVSA's "In-Service Emissions book", a "non-Cat test" with far easier limits applies.

I walked them through all, especially Chart 3 from MOT inspection manual for private passenger and light commercial vehicles

(wherein ?most Bongos land in the lower-right box) and the absence of Bongos from pp97-99 of DVSA In Service Exhaust Emission Standards for Road Vehicles 19th edition (presumably because never marketed in the UK).

They will retest my emissions at 4pm today, so fingers-crossed ...
So grateful to Bongolia and Doone/Allan ... this may save me £'00s

[Winnie-bongo]

From Royston's PDF

[Winnie-bongo]

Page 2

[Winnie-bongo]

Page3

[Winnie-bongo]

Page 4

[Mrs Feynmans Bongos]

It was re-MOTed today (I was too busy yesterday), having only driven 3 miles from home, but temperature needle had risen to 11 o'clock (i.e. no commute held in 3rd as Tuesday).

Of course it PASSED, no surprise there given the "minibus" limits for CO, HC are ~12, 6x respectively those for cars.

But mild surprise today's readings were 0.211% CO, 123 ppm HC, so the CO would have passed for cars today!

Sure this is telling me something (beyond "old ladies might behave differently day by day" ) but what, given my usage details above?

Eg too much Redex or over-revving can give excess CO?
Any final thoughts from Bongoland?
Thanks again anyway (hopefully no MoT drama next year)

[Bongolia]

Great stuff.
Additives can do strange things to emmisions so not a fan except for diesel treatments.
Temperature plays a big part in emmisions testing so really a temp probe should be used to ensure engine temp is hot enough and engine speed measured but these things a fiddly ( especially when the engines in the cab and a side conversion may make the access to the motor to get the oil temp an issue)and take time and although the analysers are designed to make the operator wait (so time taken is theoretically the same) in practice you can roll a fag or make a coffee while the analyser counts down.

[g8dhe]

Yes this info has just saved me a problematic week! It failed the first MoT on emissions and then I remembered the change of procedure that had been mentioned, printing out the the document and the DVSA response that it needs to be brought to the testing stations attention has produced the required response this morning! Just for future, links here too the documents required;
http://www.g8dhe.net/bongo_images/MoT_P ... SSIONS.pdf
http://www.g8dhe.net/bongo_images/MoT_P ... nse_pp.jpg

[Winnie-bongo]

The link I posted above for a PDF on petrol Bongo or Freda emissions has been updated with my replies from DVSA and as I can't edit the post I am having to put it here.
I have pointed out to DVSA that testers don't seem to understand and DVSA are now hopefully including it in annual training and assessments for testers

https://www.facebook.com/groups/MazdaBo ... 995225733/