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msitpro

MOT emissions data log - HFC, Decat etc... please contribute

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I have read a lot about people adding HFCs (High Flow Catalyst)/Sports Cats and saying they can't get them to pass an MOT emissions test, either from new, or sometimes after a few years of being on a car.

 

I think it would be very beneficial to the community if we could gather some emissions test data in one place to see what works and what doesn't in general.

 

Please could any contributors list in the below format (feel free to contribute any other data that may be relevant)

 

Engine: (DE, Rev-Up, HR)

Cat type: (HFC model, decat, OEM)

How old are the catalysts?: 

MOT test HC count: 

MOT test CO % volume: 

MOT test Lambda value: 

Has the car been ECU tuned?: (No, yes - UpRev @ Abbey, Horsham, etc. and year tuned)
What other performance modifications does the car have?: (none; or headers, intake, plenums, injectors, ITB, larger TB, spacers, etc.?)

What fuel is/was used on the car during MOT test?: (UK 98 RON V-Power, UK 97 RON BP Ultimate, Tesco Momentum 99 RON, etc.)

 

 

Thanks greatly to any respondents!

Edited by msitpro

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Baseline - 2005 UK 305z 

 

Engine: DE

Cat type: OEM

How old are the catalysts?: 14yrs 

Mileage: 85k

Stock ECU
Mods: Cone air filter, plenum spacer, cat back exhaust system, oil catch can, Shell 99 

 

PASS

 

590180600_IMG_20190808_2009540352.jpg.35e922369597db93a5a6c872e181e0f9.jpg

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Don't think my MOT test form last year had CO %. Pretty sure it was 20ppm on the HC with stock everything though as I remember it being exactly 10x lower than the allowed maximum.

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Looked at a real old MOT when the car was around 35k/4 yrs old and it burnt so clean, like 0.013 CO and 9ppm

 

Found:

1622694693_IMG_20190810_1056495062.jpg.c7a9f510cc69ada573e8c3ae4a5d6cec.jpg

Edited by davey_83
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Just re-looking at your result.. notice the CO has to be 0.20% to pass and is handily exactly that on your car.... could be too much of  a coincidence - did the MOT tester not test/couldn't test or fudge it maybe??

 

Like I said my last yr cert I'm sure only lists HC value, so maybe the tester has leeway in what equipment they have and whether it's functioning correctly etc.... More food for thought.

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HC of zero haha, you've got the world's cleanest burning VQ35!

 

I assume that's OEM cats to get CO of 0.02% ?

Edited by msitpro
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So I thought I'd get my HFCs tested before MOT time. Good job I did. Fails on CO percent.

 

Engine: DE

Cat type: custom 200 cell in OEM locations

How old are the catalysts?: 2 months.

MOT test HC count: 106-125 pp.

MOT test CO % volume: 0.37-0.66 %

MOT test Lambda value: 0.981-1.029

Has the car been ECU tuned?: No
What other performance modifications does the car have?: Injen CAI, DC Sports stainless headers, dual 2.5" to 3" cat back exhaust.

What fuel is/was used on the car during MOT test?: UK 98 RON V-Power

 

 

Going to need a second stage 200 cell cat added.

Edited by msitpro
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That's not even close to passing either pal, not good. Where would you even look to position another cat?

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Looking at just after the Y join. There's a V clamp already. Already found somebody different to weld in another V and the install a cat in the gap. Bonus will be the reduction in volume. A friend's iPhone recorded it at 118dbA at 4,000rpm ... :surrender:

Something veeeery interesting I've learned by chatting with a guy from Jetex, where I may well purchase the 76mm in/out cat, is that the effectiveness of reducing CO/HC will be greatly influenced by NOT the cell rating, but which Euro standard it's aimed at and therefore which expensive materials it uses inside. He was guessing that the units I've had installed are very cheap units. For example, Jetec sell a Euro 4 spec 200 CPSI unit at £180 ish and a Euro 5 spec 200 CPSI unit at £250 ish. Both should flow the same and therefore offer the same back-pressure but the more expensive cat will reduce CO and HC more.

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Can anyone confirm whether an ECU remap would increase emissions? My instant thoughts are that it would. Would it be more beneficial to switch to the factory map for MOT testing?

Or is it simply all about the CAT's?

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a remap can indeed affect emissions, in both positive and negative ways depending on the tune.

 

Based on my test sheet yesterday, lambda value at exhaust must be between 0.97 and 1.03 in rpm range 2450-3050rpm to pass, CO% less than 0.2 and HC less than 200ppm.

 

So, if a remap has been set so that between 2450 and 3050 rpm it is running richer than OEM within that rev range then it's going to increase HC and CO and lower the measured lambda.

 

If in combination with that, you have a high flow cat with small diameter (less surface area for the catalytic materials to act on) then this compounds the problem.

 

I can't imagine with a good condition OEM cat internals (like mine when tested last year) that with just a remap you would ever fail. They have a huge margin over the legal limits.

 

From speaking with Jetex on the matter - especially when using high flow cats, the concentration of the palladium, rhodium and platinum substrate coatings is very important. A 'cheap' 200 cell cat may only have concentrations designed for a Euro 2 car (see ebay cheap sports cats <£90) . If you look at ebay for Euro 4 qualifying cats, it's £180 minimum. The reason being that they will have higher concentrations of the precious catalytic materials on the honeycomb.

 

Just off out to a job at work - can't remember exactly what your circumstances were?

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On 23/08/2019 at 15:21, msitpro said:

a remap can indeed affect emissions, in both positive and negative ways depending on the tune.

 

Based on my test sheet yesterday, lambda value at exhaust must be between 0.97 and 1.03 in rpm range 2450-3050rpm to pass, CO% less than 0.2 and HC less than 200ppm.

 

So, if a remap has been set so that between 2450 and 3050 rpm it is running richer than OEM within that rev range then it's going to increase HC and CO and lower the measured lambda.

 

If in combination with that, you have a high flow cat with small diameter (less surface area for the catalytic materials to act on) then this compounds the problem.

 

I can't imagine with a good condition OEM cat internals (like mine when tested last year) that with just a remap you would ever fail. They have a huge margin over the legal limits.

 

From speaking with Jetex on the matter - especially when using high flow cats, the concentration of the palladium, rhodium and platinum substrate coatings is very important. A 'cheap' 200 cell cat may only have concentrations designed for a Euro 2 car (see ebay cheap sports cats <£90) . If you look at ebay for Euro 4 qualifying cats, it's £180 minimum. The reason being that they will have higher concentrations of the precious catalytic materials on the honeycomb.

 

Just off out to a job at work - can't remember exactly what your circumstances were?

Cheers for all that info, much appreciated.

Circumstance wise my HR just got through the MOT emissions this year, decent tester, went for a sprited blast and left it running to get the CAT'S as hot as possible and then it went through 2nd time, just.

Suggested it wouldn't next year basically. I run Berks and have for 8 years with no MOT issues ever. It was remapped 3 maybe 4 years back too.

Think my post was more about it being time to replace my CATS in time for next years MOT. Didn't want to just replace them and have it fail again. I think after your above post i'll replace them (over 100k on this set) and run it in the factory Map for the MOT retest when the time comes.

 

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Depending on the map, OEM map might be richer than a 'tuned' map.

 

Richer is safer for the engine (lower risk of detonation/knock) but higher emissions. Nissan may have chosen to run a little richer than perfect to protect the engine while still coming under emissions limits easily by putting very efficient (in terms of removing CO/HC) catalysts on. Hmmmm

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Engine: HR 105k miles

Cat type: Torqen HFC

How old are the catalysts?: 6 months

MOT test HC count: 18

MOT test CO % volume: 0.107

MOT test Lambda value: 0.998

 IMG_20191010_173532__01.jpg.a4aa166c748731b3fedc2f1dcc0e0fe0.jpg

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I don't suppose you know your tester very well?

 

I now have 3 200 cell cats in my exhaust and can only just manage 0.19% and 124 ppm HC on my MOT yesterday on about the 4th go (by this point the brake fluid starts boiling as it runs next to my stainless headers)

 

I visited my tester last week and we could not get below 0.28 if we actually ran it at 2800rpm ish for the whole test as is supposed to happen. You can cheat it VERY easily by just idling until the last few seconds, as it only counts the values at the end of the supposed 30 second long test.

 

I'm on stock tune still.... I wonder if there's some kind of issue with my engine hmmmm

Edited by msitpro

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Not really - they're pretty friendly, but didn't bodge the test at all. 

 

My full exhaust set up is Torqen HFC, Miltek Y Pipe + Cobra Back Box. 

 

The car has been uprev remapped

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Thinking about the DE / DE RevUp / HR engines, could there be a difference in emissions based on the intake plenum changes? Perhaps those of us with plenum spacers could be inadvertently causing problems?

 

DE + DE RevUP have the same upper but different lower plenum's and the front two cylinders are known to get less air fed to them. HR obviously had a significant redesign with two intakes/throttles.

 

Being a GT4, my car has the DE RevUP motor and I have a Motordyne 3/16" spacer fitted.

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