Mot Engine Emissions :(

[Guest Takumi]

Had an MOT failure today,

 

everything fine, except the emissions.. (2.0L on 33mm bike carbs)

 

CO 6.055% (<3.50% limit)

HC 2601ppm (<1200ppm limit)

 

I've screwed in the pilot screw fully for the idle circuit, to cut down the idle fueling, and dropped the main needle jet by 2 notches to reduce fuel from there also. The car is idling ok.. I also notice the vacuum adv pipe from the manifold was collapsed -now replaced - wondered if poor ignition timing would affect the idle emissions also..?

 

Also I'm thinkng the fuel in the carb bowls might be contaminated with oil from the crank case recirculation . .? What about Super99 fuel and some octane addtives/or redex type stuff..?

 

 

unhappy tak

[Guest chris brown]

Had an MOT failure today,

 

everything fine, except the emissions.. (2.0L on 33mm bike carbs)

 

CO 6.055% (<3.50% limit)

HC 2601ppm (<1200ppm limit)

 

I've screwed in the pilot screw fully for the idle circuit, to cut down the idle fueling, and dropped the main needle jet by 2 notches to reduce fuel from there also. The car is idling ok.. I also notice the vacuum adv pipe from the manifold was collapsed -now replaced - wondered if poor ignition timing would affect the idle emissions also..?

 

Also I'm thinkng the fuel in the carb bowls might be contaminated with oil from the crank case recirculation . .? What about Super99 fuel and some octane addtives/or redex type stuff..?

unhappy tak

The CO is not a problem it just needs weakening off a bit but the HC is another matter try feeding the breather (the one below the inlet manifold and any other for that matter) into a catch tank rather than having it connected to the manifold this way it isn’t burning the oil mist if the sump is pressurising a little. It does mean getting rid of the valve in the breather line so as to make it free flowing but might get over the problem. Ignition timing won’t help but I don’t think it would raise the HC. Changing the fuel type I don’t think will help and as for Redex etc as they are oil (upper cylinder lube) they would make the matter worse.

[Big Jim]

Had an MOT failure today,

 

everything fine, except the emissions.. (2.0L on 33mm bike carbs)

 

CO 6.055% (<3.50% limit)

HC 2601ppm (<1200ppm limit)

 

I've screwed in the pilot screw fully for the idle circuit, to cut down the idle fueling, and dropped the main needle jet by 2 notches to reduce fuel from there also. The car is idling ok.. I also notice the vacuum adv pipe from the manifold was collapsed -now replaced - wondered if poor ignition timing would affect the idle emissions also..?

 

Also I'm thinkng the fuel in the carb bowls might be contaminated with oil from the crank case recirculation . .? What about Super99 fuel and some octane addtives/or redex type stuff..?

unhappy tak

 

What engine Tak? If it's a Pinto, then it should only be visual smoke test, not put on the m/c.

 

Details here

 

This is the page out of the MOT manual. go educate the grease monkey.

[Guest chris brown]

What engine Tak? If it's a Pinto, then it should only be visual smoke test, not put on the m/c.

 

Details here

 

This is the page out of the MOT manual. go educate the grease monkey.

Unfortunately Jim the book you got that out of is now defunct and all instructions come up on the computer. Mine is tested as per the donor the only way now to get a smoke only test is to have a Q plate. Well that’s the way I see it.

[chris n]

Had my Hood MOT a couple of weeks a go. Theres the way the C/O was tested on on a SUN computer.

 

Engine at working temp

Hold engine revs at 2500 for 20 seconds

Then at idle for 20 seconds

Insert C/O meter probe into exhaust and wait til the reading settles

 

The Testers Manual

[Guest Takumi]

Yea,

That is what was done. I had thought that oil vapour was finding its way in there.. >Going to make a catch tank and ditch the valve.. Hopefully the emissions will be down, no way to really check without a gas analyser

[Guest Takumi]

Got a Weber DGAV and manifold to try on the emissions front.

 

All running, but the idle is hunting quite alot, not really hunting, idles then slowly stutters and the revs drop and almost dies, then suddenly blipps back upto speed, then slowerly dies a bit more, eventually stalling..

 

When you open the throttle, pick up is fine, and sounds good too..

 

What is happening, I'm thinking a floating blockage somewhere, ,,

 

 

hmmm....hlep

[Bob Tucker]

Back to checking all the usual suspects Tak. but it sounds too rich, so unlikely to be a blockage.

Check the plugs for a clue.

Too weak would spit back on revving up, & possibly just die completely.

 

What fuel pump are you using? What pressure regulator?

 

Is the choke opening properly?

Is there an air leak anywhere?

Is the float height set right?

Are the right jets fitted?

Is the idle mixture right?

 

HTH Bob

[Guest Takumi]

As I understood it, it was a standard carb, not modified in any way..

 

But I will re adjust the idle mix, and check for and obvious leaks..

[Guest Takumi]

All is working now, all it turned out to be was a weak mixture.. 1 more turn out, and its fine.

 

Thanks for all the pointers.. MOT on its way

[Guest Takumi]

MOT PASS !!

 

CO 0.9% few..

 

 

 

 

 

smiles smiles smiles..

[Big Jim]

Unfortunately Jim the book you got that out of is now defunct and all instructions come up on the computer. Mine is tested as per the donor the only way now to get a smoke only test is to have a Q plate. Well that’s the way I see it.

 

 

OK Chris, we were both a little "OFF THE MARK" on this one.

 

 

From the link you put up, that is not the "official MOT manual" but a "perception" of the official manual, certain items have been missed.

 

Having had the Official manual checked on the official computer today, by a MOT inspector, this is how it really is:................

 

Kitcars registered after 1998 (when SVA first came in) will be tested to the age of the engine, (and it's up to the owner to prove the age of the engine, usually by the doner document)

This figure will then be on the official records for that vehicle. When MOT time comes along, the vehicle will need to pass those very same limits.

Now a Kitcar that was registered BEFORE 1st August 1998, will be deemed to be of 1975 vintage, and the emmisions test is "VISUAL SMOKE ONLY"

 

The basis is then, if your car was SVA'd, it needs to pass the same emmisions at MOT as it did at SVA, and those figures are on the computer records for your vehicle.

If on the other hand, you kitcar was built earlier than SVA, then it's visual smoke only.

 

Once I get my hands on a copy of the acutal page from the manual, I'll post it on the NW website.

 

 

Jim

[Guest alan rowe]

Jim - your post was interesting reading ---- but what if the car was built post 1998 but registered on an age related plate (same vintage as the donor car - pre 1998) and fitted with a 1997 engine at the time of the SVA

 

No MOT required for the first 3 years but the emmision figures printed on the reg doc appear to be the most stringent ones (ie the latest ones)

 

Your thoughts and comments would be appreciated

 

A

[Guest robinj66]

If you had a post 1995 engine fitted at SVA then you will have been tested to the most stringent emissions and will end up with those on your V5. Presumably, if you passed the SVA with a modern engine but later replaced it with a much older engine (incapable of meeting the stringent regs) presumably you would have to take the issue up with the DVLA, enclosing proof of age for the new engine with your notification of change of engine

 

One thing to note - do check that the emissions on your V5 are correct. Mine weren't and after a lot of faffing about, it turned out the SVA tester had put the wrong code on the form sent off to DVLA

[Big Jim]

Jim - your post was interesting reading ---- but what if the car was built post 1998 but registered on an age related plate (same vintage as the donor car - pre 1998) and fitted with a 1997 engine at the time of the SVA

 

No MOT required for the first 3 years but the emmision figures printed on the reg doc appear to be the most stringent ones (ie the latest ones)

 

Your thoughts and comments would be appreciated

 

A

Haven't got the page in front of me at the moment, so can't quote it (will post the page on NW website when I get it)

but basically, when you had your SVA done, you had to give the age of the engine, (post 1995 engines also have to have Cats fitted) so whatever you had to pass at SVA, will be the same restrictions at MOT, and they'll be in the DVLA system attached to your car. When the MOT inspector punches in your reg number, it comes up on his computer just what it has to achieve.