No-cats MOT : emissions results

[Doughie]

Well i knew it would be borderline for the Supe with no-cats to get through emissions, and it was unfortunately just the wrong side of borderline

 

Results :

 

Natural idle :

CO = 0.50%  (limit is 0.50%!) = PASS

 

Fast Idle (2500rpm approx.) :

HC = 66ppm (limit is 200ppm) = PASS

CO = 0.55% (limit is 0.30%) = FAIL

 

so passed Hydrocarbons, and passed the Carbon monoxide at idle, but didn't make it at the "fast idle" speed on CO.      Didn't realise that the limit for CO at higher revs is tighter than at idle.   (0.3%  vs. 0.5%)

 

Got the 2nd-cat whacked on it already and submitting for free re-test this week.

 

will let you all know the emissions results on that (will be interesting to see the effect of the 2nd-cat).

 

cheers

Stu

No-MOT Supra :sad:

No-1st/2nd/5th/reverse gear  VW Golf :sad:

 

[Alex]

Did you use SUL and Millers for your fuel, have you had a recent oil change? What oil are you running? Which sparks are you running and how old are they? Did you use any fuel system cleaner before the MOT?

 

All of these things could have affected your M.O.T. result...

 

 

[Ian C]

I just had mine MOT'd, it has the 2nd (rearmost) CAT still on, and it squeaked in at .28%, .02% under the limit.  Phew.  I doubt anything with no CATs would pass, suerly?

 

-Ian

[Alex]

But your car is mental, Ian "I run 1.45bar" C, so I doubt it can ever push out really low emissions as it so damned powerful!!

 

 

[Digsy]

I'm assuming that they do the test from a cold start?

 

In this case, surely refitting the first cats would do the most good, since pre-cats are usually designed specifically to light off first from cold.

 

Darren

(car still on the boat)

 

[Alex]

Actually Ian where did you get it MOT'd mine needs to be done like yesturday!

[Guest Martin F]

 

Emissions tests are normally done when the car is warm.

 

The oil is expected to be at a certain temperature before measurements are made. The oil temperature should be recorded on the results sheet.

 

 

[Doughie]

OK here are the answers :

 

1) Yes, using Super Unleaded

 

2) Yes, using 1 bottle of Millers Octane booster (i did actually wonder if this would increase or decrease the emissions results.    - any opinions here please ?)

 

3) Oil is Valvoline Synpower fully-synthetic.   Changed quite recently by Leon.   (about 2 months ago, and done maybe 1500 miles since then)

 

4) My spark plugs are, to my knowledge, the original platinum-tipped ones.   I've had the car a year and they've not been changed.   It's a 1995 car.    Car's done 48,000 miles now.    plugs supposed to be good for 60,000 miles, but Alex are you saying that new plugs may reduce stuff like Hydrocarbons due to better spark etc. ?   I'm certainly not aware of any misfiring at all.  car runs clean.

 

5) Didn't use fuel system cleaner.

 

6) Oil was hot, recorded as 60deg.C    They're obliged to run the MOT with fully-warmed up oil.

 

OK folks it's now got the 2nd-cat on it, and going for MOT re-test Thursday afternoon.

It was right on the edge (but a pass) for CO at idle, and then failed CO at higher revs.     Hydrocarbons were fine.

 

I'm going to pull the EFI fuses and run it for a coupla hours before the re-test.    Anyone else think of the best way to ensure the CO is as low as possible ?   Should i run all the petrol out and re-fill the tank WITHOUT Millers ?    doubt i've got time to get sparks changed before Thursday.   would new sparks reduce CO ?

Alex, what product is this fule system cleaner you mention, and do you have practical experience that it does help emissions ?

 

 

(Edited by Doughie at 1:16 pm on July 31, 2001)

[mrpug106]

Hmmmm i in a bit of a tither here,I can't believe your car has failed the M.O.T,There are loads of supras out there with no cats,and one cat,someone must have had an M.O.T while there car is like this?? I don,t believe you have to keep putting the cats back on!!!

How come they passed,who done it?

Lance...(about to have a the 2nd cat removed)

[Digsy]

Catalysts don't work until the brick temperature reaches about 300 degreesC. They work best between 400 and 800. How long it takes them to get that hot depends (mainly) upon the size of the CAT and the distance to the exhaust manifold, therefore the pre-cats will warm up much faster but because they are smaller they will also cool down faster too. Once the main cats are hot, which will take much longer, they will stay hot for longer.

 

60 degrees oil temp is certianly warm, but its far from hot. I would expect the oil in a rip-snorting Supra to be hovering around the 100degree mark for most of the time. I don't know how oil temperature maps to cat temperature during warm up but I'm wondering whether (from a cold start) the oil will reach 60 degrees before the main cat reaches 300?

 

Also, modified fuelling will mess up a cat depending upon the type. If the cat is "three-way" (lowers NOx, HC and CO) then the mixture needs to be spot on (stochiometric) for the cat to work properly. Oxidising cats only lower HC and CO and require a lean mixture.

 

I think I've confused myself now...

 

Darren

[Branners]

Quote: from mrpug106 on 2:07 pm on July 31, 2001[br]Hmmmm i in a bit of a tither here,I can't believe your car has failed the M.O.T,There are loads of supras out there with no cats,and one cat,someone must have had an M.O.T while there car is like this?? I don,t believe you have to keep putting the cats back on!!!

How come they passed,who done it?

Lance...(about to have a the 2nd cat removed)

 

Theres only 1 car I know of that has passed an MOT without cats, and thats because they got it pushed through as not requiring cats.

 

You may find a lax MOT station who fails to pick it up, but if you run without cats then chances are you will fail. Most people who are running without cats have only changed them recently. My approach will be to give Leon my car and ask him to do the work required to get it past an MOT....then it will come back with an MOT and the cats will not be on it.

 

JB

[Doughie]

Well if a car is 1992 or after, then it is categorised as "requiring CATS".    The MOT station should be able to figure it out !

I'm not sure of the *exact* date when cats became mandatory for manufacturers to fit, but the only way you can swing it is if your car is a 92 car and you convince the MOT station it's a pre-cat car.  

 

Interestingly enough, when I picked the car up, the MOT bloke didn't mention the cats - i really don't think he checked for the PRESENCE of cats at all.    I checked the emissions read-out and argued a bit (!), and he said something like "it's got a non-standard exhaust and that might have something to do with why it failed emissions".    he did not say to me "It hasn't got any cats on it".    

Fortunately for the re-test on Thursday, i've got an exact time of 2pm for the test.   So i'm going to take it for a long fast drive to get the 2nd cat fair-dinkum ROASTING hot so that it retains as much heat as possible for the emissions test.      

 

if it STILL fails with just the 2nd-cat fitted then i'll just have to get the 1st cat put back on as well.   But i'm sure it won't come to that.

 

fingers crossed then.

[mrpug106]

Fingers crossed and Balls to the wall...!

Good Luck with the M.O.T.

Lance......

[Digsy]

I'm chatting to my friend (down the corridor, with the big brain) about cat warm up times this via e-mail at the moment. Pre-cats have to light off within 25 seconds of a cold start (these days, anyway). I reckon this time has come down over the years, but for a car fitted with pre-cats  you could still assume that the initial light off time would be quick enough to beat the oil warm-up time.

 

I don't have a typical light-off time for a main cat only yet. Watch this space...your nutter pre-MOT drive may not be necessary after all!

 

Darren

 

[Alex]

Dougie,

 

I have no facts of figures to back up my Fuel Cleaner query but I have used, in my Sup, Nitrox's Fuel System cleaner with no ill affect to my knowledge. It's supposed to be an octane booster and engine cleaner. I've also tried some other injector cleaners to see if I get better response. It used to work a treat on my old Rover. But I think my Supra Engine is too clean to require cleaning so I don't bother using any at the moment. Having said that I was going to stick a bottle through about two tanks before I get an MOT done, (that'll be about 1/2 a day before then!!).

 

My point of asking was to see if anyone else came up with any comment about fuel system cleaners and which ones to use and which to avoid.

 

I have to get CAT friendly stuff but you could push through some seriously nasty cleaner before hand with no cats in and make sure that your car isn't contaminating its own results with sh*t that's got coked up in side.

 

As for the Spark plugs - I was just wondering if you were running say the HKS or NGK cold plugs as I have the HKS ones and I was looking to compare.

 

Unfortunately I have lots of ideas but no financial backing or mechanical know how to test all of my theories!!!

 

 

[Doughie]

 

OK I spoke to Leon earlier today about any advice he could give and he suggested not using Millers when the MOt's done.   He even suggested using 95 octane fuel !  

I have a feeling that i have almost a full tank in the car right now which is a bit annoying as i doubt i'll be able ti run it down before thursday.

 

ok well we'll see what occurs.

 

 

[Digsy]

Okay, stop press on cat light up time:

 

The whole point of having a pre-cat is so that your main cat can take all the time it needs to warm up (within reason). Therefore, systems with pre-cats may have slower light off times for the main cat that a system with just a main cat.

 

ALSO, the reaction in the pre-cat CREATES heat, so it assists  in the light off of the main cat.

 

A main cat with a pre cat fitted will light off about 1 minute after the pre-cat (about 1.5 minutes after key-on). Without a pre-cat it will take longer.

 

I would ask them to idle your car for at least two minutes before doing the emissions test.

 

As a side point, I have just got my grubby mits on the emissions regulations for Japan and Europe back to 1993 to see how they compare. Unfortunately I cannot relate them back to the figures used for the MOT because the tests and units are all different, but it should be possible to compare the two.

 

...and a final note from another thread, I cannot find any reference to Japanese engines having to be mapped for anything except 95RON.

 

Darren

 

[Ian C]

Quote: from Alex Holdroyd on 12:38 pm on July 31, 2001[br]Actually Ian where did you get it MOT'd mine needs to be done like yesturday!

 

EMG Ford in Thetford.  Yes, I know it's a way out, but they are bloody good to their customers.  When it was going to take more than 1 hour because of problems with another car, they gave me their rapid fit van so I could go and visit my parents!  That's what you get for sticking with a good garage for five years.

 

-Ian

[Phil]

When I had mine MOT'd with the first cat out I just took it for a big blast up and down some nearby A road's and had them do the emissions as soon as I pulled onto the ramp - it absolutely sailed through.

 

I did put the figures up but I can't find the thread at the moment.

 

[Doughie]

HOOORAHHHHHHHHHHH !!!!!!

 

the Supe went in for the MOT re-test today (having put the 2nd-cat on since the original MOT emissions failure).

 

Car absolutely SAILED through.     The bloke said was a completely different set of readings to 1st time.    I made sure the CAT was nice and hot immediately before the test, and also pulled both EFI fuses for 10 minutes after fitting the 2nd cat.    

 

So in summary folks, if you are concerned about your de-cat supe and the MOT,  the car will likely fail with no cats, but sails through with 1 cat on (2nd cat is easier to swap over).

 

Also it was a useful exercise to see what the difference is with the 2nd cat on and off.    It DEFINITELY picks up slower with the 2nd-cat on so that was useful to know.

 

Now i've passed, it's : bleed valve OPEN, NUR baffle OUT, 2nd-cat OFF. :smile:

 

cheers