Confirm:S2 needs cat if first registered post 31/7/95

[GeoffSmith]

[Edit 1/6/2011 : see Post #39]

[Edit 25/9/2014 : see Post #80]

I finally got the turbo out of the car to port the wastegate.

As I peered inside the lump of scrap iron that is the precat, what do you think I saw......... absolutely nothing. The precat is devoid of anything. Am I too late to join Matt's PCE group buy?

Now this is all very interesting, because the previous owner had hollowed out the main cat and I have fitted a Peco, yet the car has passed the emissions test on at least two MoT tests. It would appear that the closed loop system is sufficient by itself to pass the UK requirements.

Now before all you S2 owners go out and hollow out the pre and main cat, please be responsible and spare a thought for the planet.

Geoff

[Dico]

Bent mot tester!

No, not in the bent Gary sense

[GeoffSmith]

Bent mot tester!

No, not in the bent Gary sense

No. Two different garages.

[Enright]

Mine came close to passing the cat-equipped MOT test after I fitted the O2 sensor and V5, and it always ran rich before that, so the result doesn't completely surprise me. But the lack of any insert in the pre-cat does.

[GeoffSmith]

Mine came close to passing the cat-equipped MOT test after I fitted the O2 sensor and V5, and it always ran rich before that, so the result doesn't completely surprise me. But the lack of any insert in the pre-cat does.

Bugger it, I'm going for a PCE.

[ailwyn]

Mine came close to passing the cat-equipped MOT test after I fitted the O2 sensor and V5

This is where my concern lies with hollowing out the pre-cat (assuming it has any stuffing).

If the only difference between the SE and S2 is the chip, O2 sensor and CAT(s), why (if a cat is not required) does Enright's not pass the S2 test?

What could cause my S2 to fail the emissions test (close ain't close enough) if I remove the precat?

[Enright]

Ailwyn, mine should not be used as the benchmark for that comparison.

I went for a V5 and O2 sensor on my SE almost out of desperation, because my car had been hideously over-fuelling since I bought it, and I'd never been able to work out why. I still haven't either, despite trying all of the usual solutions! But turning it into a closed loop system effectively put a big elastoplast over the problem and forced it to reduce fuelling in line with the O2 sensor's reading.

My Elan did about 20mpg before I fitted them, no matter what I did to it or how I drove it.

The emissions quartered to almost within catalytic converter equipped limits, while at the same time finally giving me the fuel economy that I'd always heard the Elan was capable of.

Hey, if it had been performing properly in the first place then it may have got even better, but if that had been the case I probably wouldn't have gone down that route anyway!

[GeoffSmith]

Possible fallback position if we need a cat....


Click pic for details.

[Jon]

From experiance I can confirm that you don't need a CAT to pass the emissions test - but it is pretty tight without one!

I have had mine 8 years and only discovered that I was without a CAT a couple of years ago.

I did notice that some of the earlier garages had tested the Elan as an S1 (though the records showed that it was actually still within the tolerence required for an S2).

It certainly does help if you also have a friendly garage though...

[GeoffSmith]

Jon,

Do you still have the pre-cat in place or has that gone as well?

Geoff

[max and andy]

hi folks.when i bought my car the main cat was buggerd .because i skint myself buying the best elan a could.i went for the cheapest option and removed it .thinking i would replace it when next m.o.t was due.now m.o.t is just around the corner.do i need to replace or not.to beat the emissions test .or will pre cat do.i know there has been a couple of comments.but not enough for me to go to goodwood instead of keeping the money for a cat.please advice.max and andy cheers.

[GeoffSmith]

Personally, I'd check the base timing and provided the ancillaries (sensors {especially O2 sensor}, plugs etc) are up to scratch, you shouldn't have a problem with the pre-cat in place.

[nickb]

I've had a Peco fitted to my S2 for the last couple of years and had no problems passing the the mot, prior to this my main cat was buggered so I had a piece of pipe welded in it's place and the car still passed the mot. My precat is still present but I can't believe there is much left of it as my main cat was empty apart from a lump of something which kept blocking the hole.

Nick

[max and andy]

mine was the same and i did the pipe thing.maxine

[Rogerf]

Mine passed today with Peco and pre cat !
Roger

[max and andy]

cheers roger. max and andy did you get any numbers .

[GeoffSmith]

Mine passes with NO pre-cat and a Peco.

There are some figures on the Piper thread.

[GeoffSmith]

A recap and summary of the details of my experiences:

22. CO emissions (mixture): At the time of writing, for vehicles first used between 1st August 1975 and 31st July 1986 (P to C registration), the CO level must not exceed 4.5% by volume. For vehicles first used between 1st August 1986 and 31st July 1992 (D to J registration), the CO level must not exceed 3.5% by volume. Vehicles first used after 1st August 1992 (K registration) must conform to the manufacturer's specification. The MOT tester has access to a DOT database or emissions handbook, which lists the CO and HC limits for each make and model of vehicle. The CO level is measured with the engine at idle speed, and at "fast idle". The following limits are given as a general guide: At idle speed - CO level no more than 0.5% At "fast idle" (2500 to 3000 rpm) - CO level no more than 0.3% (minimum oil temperature 60ºC) If the CO level cannot be reduced far enough to pass the test (and the fuel and ignition systems are otherwise in good condition) then the carburettor is badly worn, or there is some problem in the fuel injection system or catalytic converter (as applicable).

23. HC emissions: With the CO within limits, HC emissions for vehicles first used between 1st August 1975 and 31st July 1992 (P to J registration) must not exceed 1200 ppm. Vehicles first used after 1st August 1992 (K registration) must conform to the manufacturer's specification. The MOT tester has access to a DOT database or emissions handbook, which lists the CO and HC limits for each make and model of vehicle. The HC level is measured with the engine at "fast idle". The following is given as a general guide: At "fast idle" (2500 to 3000 rpm) - HC level no more than 200 ppm (minimum oil temperature 60ºC)
Excessive HC emissions are caused by incomplete combustion, the causes of which can include oil being burnt, mechanical wear and ignition/fuel system malfunction.

Previously, my car had both (pre-cat and main) cats removed and now I have a Peco exhaust with no cats.

Both testing stations that have passed my car used a single CO maximum limit of 3.5% and HC maximum limit of 1200ppm. I did question this at my first MoT, but was told that the figures were taken directly from the DoT database. The actual figures I achieved at my last MoT were 0.423% and 95ppm respectively. These are taken from the computerised Sun DGA 2500 printout. I am unsure whether the CO figure is taken at idle or fast idle, however it is obviously below the 0.5% @ idle but above the 0.3% @ fast idle general guide figures quoted in Haynes.

Do any S2 owners have different limit figures (i.e. idle and fast idle limits for CO emissions) and if so, what are those limits?

[M100 TWO]

Lotus did not type approve the S2, so as far as the DVLA is concerned the S2 emissions are as for the SE you need to ask for the car to be tested as if it was a 1992 SE

[max and andy]

Does that mean there are no figures in th book for S2s, the MOT tester has to look at the SE one's. A&M