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K Series MOT emissions


Richardoh

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Anyone able to recommend a 'Caterham friendly' place to take a 2003 K Series for a MOT retest in (or near) North Yorkshire? Ours has just failed on its emissions. It sailed through everything else but we've only had it a year so haven't yet had to find a local place to help us look after it.

Any suggestions or advice very welcome.

 

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Hi all. Really helpful comments so far, thanks. As I understand it, I do have to have a proper test due to build date. It does have a cat - inside 421 Powerspeed exhaust. Emissions were some way out, but I have already been advised to give it a really good run with some cleaner in as that might bring it down far enough. That said, the (extensive) paperwork with the car suggests emissions has been a problem before. 

Did one fab run towards the Dales yesterday (no hardship in this weather!) and hopefully some more today. Perhaps it just needs that but if it does need more help from someone who really knows about Caterhams after its retest, I'd certainly like to know where others do this.

Re the V5 - am I being really thick - there doesn't seem to be a section 18 - goes straight from 17 to 19... 

Any further advice very welcome! 

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It would be useful to check what tests it failed on. For example Lambda usually means a leak that can be easily fixed with sealant and CO is possibly a cold cat.

The "friendly" ones are usually the patient ones who let things heat up and try a few times. Most mechanics are interested in the cars so a friendly chat with the tester may help. I've seen it failing but then all of sudden improve which is probably the cat getting to temperature.
 

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Definitely going to have everything really hot before the next test. 

For those of you who are interested / really understand these things:

Fast idle: 

CO 2.17 vs 0.30 to pass, HC 406 vs 200 to pass, Lambda pass (1.012 vs 1.090 to pass)

Second Fast Idle:

CO 2.00, HC 296, Lambda 0.993

Natural Idle:

CO 4.54 vs 0.50 to pass

 

 

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Yes, that is a long way out.  The high CO plus high HC point to running too rich, although your lambda suggests otherwise.  It does seem that either your cat is defective or not hot enough.

  1. Where is the oxygen sensor located, and how far away is it from the cat?
  2. Is the air filter clean and in good nick?
  3. Is your induction standard CC/Rover or do you have TBs?
  4. What ECU do you have? 
  5. Has the car ever been remapped?

JV
 

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@John Vine - Would an exhaust manifold air leak ahead of the lambda draw in air and give similar readings? Lambda would think it was running lean so ECU would rich it up a bit until the lambda was reading correctly, at which point the cylinder combustion would be rich.
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Andrew, I think you're spot on.  A falsely enriched mixture would give both high HC and high CO readings. 

Also, the OP has an exhaust collector for his 4-2-1 Powerspeed (presumably ahead of the sensor), so it could well be leaking (that is, sucking in air) there.

Btw, do MOT gas analyzers actually read the O2 sensor output, or merely calculate a lambda value from other inputs?

JV

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I have to say I'm loving how you're all engaging with my little problem - and you are really helping me out, so thank you!

Latest update for you. Having run the car quite a bit (and reasonably enthusiastically at times) over the weekend, and having put some engine cleaner through, we had a retest done today. The car was warmer for the test too, but not straight off a hard run.

It failed again - but I am a glass half full kind of person, and the good news is that it's improved a lot, and more than that, I think it's maybe clarified a bit where the problem could be. So here's what I have now:

Fast idle:
CO now 0.82 vs 0.30 to pass (and was 2.17)
HC now 207 vs 200 to pass (and was 406)
Lambda still pass

Second fast idle:
CO now 1.22 vs 0.30 to pass (and was 2.00)
HC now 76 vs 200 to pass (and was 296)
Lambda still pass

Natural idle:
CO now 2.31 vs 0.50 to pass (and was 4.54)

So our big issue is really the CO - the HC is more or less there now.

To answer some other questions from the string:

  • Engine was hotter this time than last - and the car hadn't run much since coming out of hibernation when it went for the first test - lesson learned there
  • Car has a pretty sound history, very dedicated and savvy previous owners and purchased from BaT last year. Generally the car seems sound, and runs very nicely, albeit a bit lumpy at idle
  • Haven't been able to get my hands on values for previous tests. It did fail on emissions a few years ago but has passed since then
  • I haven't checked plugs or air filter as yet. Likewise proper examination of the cat
  • The spec sheet I have says it had a DVA K14 upgrade, verniers & 52mm TB back in early 2008. ECU is marked 75806, Supersport/Dec03/Upgrade​

For those of you still interested in the case... over to you! What would you do next?

Thanks again
Richard

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My car is a 1.8K DVA K13 with TBs and Emerald (mapped). One of the issues when I take mine for MoT is getting the readings to remain "stable" and stay within the limits for the 30 second fast idle test. This normally takes a few cycles.

The issue I found was trying to keep my foot still on the throttle as every time I speeded up or slowed down the RPM a little within the 2,500 to 3,000 range, the initial change is engine speed caused a 'blip' in the readings which normally jumped outside of the test pass range foe a couple of seconds.

The way around this was to control the engine speed by a method other than a human foot, a long stick would do or using the idel speed control screw on the accelerator, one I could keep the RPM very constant, the readings were solid.

That may help some people.

Thanks

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The MOT testers shove a probe up the tail pipe. The oxygen content it measures determines the lambda reading. Usually with a leaky system the MOT probe will detect high oxygen but the cars sensor will think everything is fine and the mixture will not be enriched. Although if a leak is before the cars probe then the ECU may want to enrich. Now that the system is being tested hotter the lambda tests seem to being passed easily where they struggled previously this could be because heat expansion is helping to seal any gaps. My feeling is there is a minor leak that could benefit from sealant but it is not enough to worry about.

If it's not leaking and the plugs look clean I would look at getting the timing spot on.

Description of the DVA K14 package at - http://www.dvapower.co.uk/ I think the basic aim of the upgrade is to get more fuel into the combustion chamber and at the right time. If the timing is not right there will be unburnt fuel.

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...but is that what you're asking?

Maybe, Jonathan --  I'm not sure!  I was wondering whether the gas analyzer (a) read the car's own lambda sensor output, or (b) measured O2 independently, or © calculated a lambda value from other inputs, such as a combination of HC, CO2 and CO.  From post #22, it seems that it does (b) and then derives a lambda value from that.

JV

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  • 1 month later...

Richardoh, did you ever get your car through the test and if so, how?

I am in exactly the same position (1.8 k-series, DVA tuned, TBs, Powerspeed 4-2-1 and re-mapped) and high on the CO.  The HC was OK but the lambda failed too.

I fitted a new lambda sensor but if anything the CO is now worse!

It would be good to know what you did, or what I can do?

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