Car still failed MOT on emissions.

The problem is emissions on "fast idle".

I had a new CAT & O2 sensor two years ago.

Any ideas?

S

If fast idle, I assume that's when cold?

The cat won't be effective then, and the mixture rich due to 'choke' enrichment by ECU. So it may be 'overcarburetting' leading to high hydrocarbons, CO, perhaps soot. Certainly my older cars (incl a 2004 Mazda3) do that- Mazda 3 almost gases us with hydrocarbons when I reverse out of the driveway when cold.

They need to give you more details as to what the issue (failure) actually is: NOx, O2, CO, CO2, hydrocarbons, particulates, not holding fast idle, wrong fast idle speed, etc. 'Emissions' isn't actual measurement or actual item that can be measured! If they can't tell you, find a mechanic who can or ask the AA/RAC technical assistance (exists?).

Also just check that the 'fast idle' test applies to your vehicle- maybe it doesn't if it's old enough.

How do they do the fast idle? Start it cold, or gently open the throttle?

To go with the cat, maybe other sensors need a check or clean too- MAF/IAT (does it have one), MAP (does it have one) etc.

Quick check for vacuum won't hurt either (but I think it's unlikely).

Hmmm, just found this site UKMOT which says:

It then goes on to talk about an extended test in case of fast idle failure. There is an annex to this with specified values for your car. If your car isn't in the annex and pre Aug 1 1995, it only has to meet non-catalyst standards.

So assuming failure on the Basic test run, it will be failure on fast idle CO or HC. Assuming it passed the normal idle speed test (CO only)- if it got that far- we could guesstimate and say it was HC (HydroCarbons) it failed on at the specs quoted above. This indicates mixture enrichment for some reason, or a possible problem with the ignition system, or maybe the cat isn't at operating temp (was the car warmed up for 10-20 mins). Note the extended test requires a measurement of oil temp to ensure the engine is at correct operating temp- your water temp gauge can be misleading as cars are designed to warm the block and surrounding water jacket quickly- to help get combustion and emissions under control- the rest of the engine takes time to get to real operating temp, this is worse on newer cars than older ones.

Another page UKMOT has- Avoiding MOT failure Emissions - Petrol Engines

Patrick

No worries!

(Glass crack/chip fix)
Believe me, you'll find this one of the easiest jobs compared to crawling under the car, derusting and resealing it in the dead of winter! (Brrr, those icicles are still giving me the chills... sorry!)

Yes it does compromise the screen integrity and possibly the car integrity as laminated windscreens are usually bonded to the frame, forming part of the structure of the car.

Patrick

Brilliant stuff, cheers!

It failed on CO (0.60 rather than max 0.30)

On the original test it also failed on the natural idle (2270 rpm, should be 600-800); but oddly, it passed this on retest. I was aware of a high idling problem, as in the last couple of weeks it had developed an issue where the revs were intermittently remaining high even when the car was idling in neutral.

This afternoon I did a test for vacuum leaks: I didn't find anything, although I may have been too cautious with the carb cleaner, as I was somewhat worried about blowing myself sky high! Then I replaced the air intake pipe and MAF sensor, and did a GRND-10 reset to get the resting idle down to 750. The car drove much smoother during a road test. As the old pipe was in pretty good nick with only very slight cracking - not enough to cause a leak - I'm thinking maybe the old MAF was frazzled. I'm doing a long trip tonight, so we'll see how it behaves.

It's really frustrating that I can't check for myself if the CO emissions are now OK, without submitting it for another full MOT test

I must credit Hughie & AndyM for phone calls & Whatsapp advice this afternoon. And Andy for having recently given me Meanie's original air pipe & MAF as spares (and thank you, Meanie!)

Gotta love this club

S

EDIT: Just discovered the oil leak mentioned on the advisory: it's just the rocker cover gasket seeping again That IS very recent, I happened to check that last week and it was fine. Last year Sundance blew a bulb on the morning of the MOT test, although they were all OK the night before. I'm sure cars blowing bulbs & gaskets just before MOT time is the motoring equivalent of the car s*g itself...!

Pour in Sundance the best quality petrol you can find and drove it maybe 30-40 miles on highway before going to MOT.This is the best you can do for the cat to be in good work temp and to lower emissions, not only because the cat is warmed up but the fuel itself, it burns one idea cleaner.

I usually tend to go with an oil change, filters, sparks and every other year a new set of HT leads a day or do before MOT. Could also try pulling the lambda sensor out and blasting it till cherry red with a blow torch, as its cooling hit with a wire brush to get any scale and carbon deposits off(not sure if this is mech correct or not but I've not failed an emissions test four years in a row now)

Cheers Paul! It had new plugs and leads last summer, but I'll check the plugs again tomorrow in case anything's amiss. It does need oil change ... I might try that if I have time. And I'll clean the filter (K&N).

You and Hughie have both suggested the blowtorch thing - I'lm planning to get one tomorrow and give it a go. Is the sensor easy to disconnect? I can see where it plugs in electrically, but does the other end simply pull out?

S

To be honest it can be a pain in the backside to get out....it screws directly into the exhaust downpipe just above the flexi pipe.
Anything you can do to ensure a better burn will help with emissions.
Fingers crossed and good luck.
Oh, and glad light casing turned up, its not the best, but will do till a better one turns up.

Hi Serena, Two answers to this: ! :-
(1) If it had a new O2 sensor two years ago then I'd be surprised of it's dirty now, unless some other fault is causing it.
(2) To get it out properly you need a slotted socket, because the wire is integral with the sensor. Unplug the other end (trace the wire along its length to the plug).
Given all your posts above, once you've done basic checks (i.e. spark plugs, air filter) I'd be inclined to wait for the second MoT, especially if the garaged admitted there was a fault with the machine.
Provided all sensors are working, and the cat is working, then there shouldn't be any poor burning of fuel (CO problem), or too much fuel (HC problem), or poor conversion of CO to CO2 (cat problem).
.

Thanks for all this advice, guys! Well noted, as I need to thoroughly investigate what's happening with Sundance killing CATS.

HOWEVER, for the moment:

MOT PASS ...... after fitting the 4th CAT in 5 years ..... !!

The car went straight through the emissions test after the new one was fitted. I now have a whopping bill to pay, but I was pretty much expecting something to need replacing/welding, and it turned out to be the CAT, so hey-ho.

The previous CAT, a £170 one fitted 2yrs ago, only had a 1yr warranty (fitted by MOTEST, so beware of them fitting expensive parts for you with barely any warranty, chaps) whereas this one (KwikFit, of all places!) has a 3yr warranty, so - as the garage techie pointed out - I now have 3 years of guaranteed cost-free CAT use, because if it fails in th next 3yrs they'll replace it automatically.

MOTEST also refused to give me any help, diagnosis or investigation as to why a good quality CAT might have failed after only 2yrs. Which I pushed for because regardless of warranty, under the Sale of Goods Act if an item has a clear manufacturer's fault, then the vendor is still liable. I could pick up the old CAT when I collect the car later today, and take it to MOTEST and demand they investigate whether the CAT itself was faulty. But even if it was, they're only obliged to replace the old one, and of course that would mean losing the new one put on by Kwik Fit. So, unless I'd then be willing to fight a long battle with MOTEST to get a contribution towards having to buy a new CAT after only 2yrs, I'm screwed. Frankly it's not worth it for me, as I'm self-employed and just don't have the hours available to fight with these monkeys. If it was £500+ or whatever, then yes; but for some proportion of £170, it's just not worth the hours I'd have to spend on it. The only satisfaction I can get is to never use MOTEST again.

(Incidentally, it was also MOTEST who rammed screwdrivers through Sundance's sills last year when - in my opinion - the problem with the jacking points wasn't yet a critical one)

SO! The lesson is, when you're about to get parts fitted, check what warranty is included, and maybe ask what the garage's policy is, if a part is found to be faulty after warranty ends.

And in nicer news, Sundance is 21 years old today (13-3-97)!

S

Congratz on the MOT pass and the birthday SJ and Sundance!

Hope you're going to celebrate is true fashion #burnoutvideoplease

If I had room in the tiny car park here, I'd be doing donuts in delight, believe me!

S

Well done Serena.

As it's eating cats so often then I think you may need to dig deeper than normal items like plugs and filters. Other causes are (for example) oil leaks past the valve seals or piston rings, oil will contaminate the cats. Google for more info.

Well done Serena!

Yes the cat should have lasted many, many years.

Yes do pick up the cat and have a look at why it's failed. Maybe even the people at KwikFit will help you cut it open. For example, if it's contaminated, you need to find out why. If the core has disintegrated to a pile of powder... well you have your evidence to go back to MOTTEST (or your Fair Trading Department) and claim what is known in Oz as "not fit for the purpose for which it is sold". If you can make them give you a new cat in exchange for the busted one then at least you could sell it and retrieve some of your money.

Patrick

P.S. Happy 21st birthday Sundance... where's the party?

Sundance's last-minute appearance at Japfest Silverstone 2018, after #V6Fail!



S

... So on Monday I was haring back from Hampshire on a nice straight road at around 80 clicks, sky blue, sunroof open, stereo LOUD. Then more noise: I thought I'd driven under a military airshow (in fact it's Farnborough Airshow week, so lots of death-tech flying around).

Then I realised the loud throbbing "aeroplane" noises were happening in time with me speeding up or slowing down ... oh ****, sounds like the exhaust has died. Heart in mouth until I got back home, where I had a look, but nothing missing, nothing hanging off. I assumed it must be a broken seal or a sudden hole or whatever.

Now you may remember I have an ongoing catalytic converter saga (Sundance regularly chews them up and spits them out). The last one was fitted for MOT in March, so as the throbbing was coming from under the driver's position, off I went to the same garage in case it was related to the parts that were connected to the cat (which has a three year warranty ... #WIN!!)

They get it up on the ramp, I hear the techies mutter something like "And it's bloody stainless!" and they call me out to the ramp. The manager shows me the problem:





Basically, the little bar that was welded crossways onto the cat pipe, that fits into the rubber hangers on the car, to secure it - really it's just a small piece of rebar - had somehow ripped away from the pipe, and torn a massive hole in it.

How? God only knows. Sundance won't say.

Anyway, that was two days ago. Today I finally got the car back. The delay was because it turns out that it's now difficult to get cats that fit the F. After much searching the manager found one in Chester; luckily the supplier there had one, or the manager's next stop would have been ordering from Japan

Even then, it didn't quite fit the F's manifold pipe, and said manager had to heat the pipe on the new cat and flare it out so it fitted and he could seal it.

Fortunately this was all under warranty so I haven't paid a bean. I have been warned, though, that ready-made exhaust parts for the F are likely to disappear pretty soon and we'll need to start refurbing Hopefully that's just the gloomy prediction of one techie at an exhaust shop, but as other parts are also now becoming difficult to source, he's probably right to warn me.

Anyway, Sundance is now on his 5th - yes, 5th - cat in five years ...

S

Used to parts being scarce having a 28 year old Daihatsu and a 26 year old Saab so in this particular case it's wise to find an exhaust fabricator and get them to make up a stainless steel one up and then it'll last the life of the car, or fixable under guarantee at leasty....
Seems to be plenty of exhausts and cats on Fleabay though? Does seem a bit freaky to go through 5 cats in 5 years.....

Thinking now on this 5 cats/4 years now,i'm starting to believe that Sundance is running a little lean and it's exhaust gasses are hotter than they need to be(the manif. spec.) so it overheat the cat and shorten its life.The other thing is maybe running rich, but then the cat will not be in work temperature(it will be lower) and would eventually clogged.

Because parts are becoming more difficult to get SJ, you might be forced down the stainless route next exhaust change time. It'll be quite costly to get a stainless tubular manifold/collector made up which could fit a universal CAT. Then of course there's the other end of the CAT which will need to match whatever mid pipe you have one.

In an ideal world.....rip the whole lot off and have a full stainless pipe fitted from Powerflow, pretty sure they still offer a life time guarantee? BUT I've heard some people quoted around £1000 for this on different cars. You might be able to do it over a period though and ask them to keep it as close to standard as possible if you want

MaZZda: Yeh, I've had a few issues with idle etc., the engine needs a good clean and tune (as far as you can tune a Z5, but you know what I mean!) As soon as the V6 is back on the road then Sundance will be off the road so I can do all this stuff

Lee, yes I've wanted at least a stainless rear box for a while, but you're right: I could just go the whole hog and replace the lot. Butch has a full stainless exhaust, and the paperwork AndyB gave me says that only cost £500.

S

I imagine this is a cat-back system? Last time i went down the exhaust garage (about 3 years ago) they quoted me £450 for a cat-back system alone. I meant if you went for tubular manifold, collector, cat, mid section, back box you'd probably be looking at £800-£1000 (my estimate based on my last experiences). If it's cheaper than that then massive win get it done

Yeh, the invoice says cat back, sorry. Although it has tubular manifold etc., I assume Andy fitted all that separately. The underside of the engine and cockpit is a forest of stainless!

Re Sundance, yes, I think stainless might have to become part of my plan. Whilst I'm famous for not modding it, if I want to keep the car on the road in the long term, then replacing frail originals with something more solid/custom might eventually become a necessity ...

S

The manifold is a cast iron piece, so that should be fine for a long time unless it cracks (in which case, just replace with a 2nd hand one), but the rest of the system is prone to failure.

I'd look for a cheap and readily available cat for any other car with a similar sized engine, then build (or have built) a custom exhaust around that.

The exhaust on my BA is all made by myself, but the cat (and de-cat) is intended for a Nissan S13 - cheap and readily available cats, and an off the shelf decat, means it remains easy to swap out should I need to I simply built my own downpipe and cat-back system to fit around it

Cheers H, noted - on the "Sundance revamp" list

S

V6 Butch isn't quite back on the road (more on this shortly - I now have a proper replacement PAS hose), but until I can drive him and take Sundance off the road, I'm starting on the non-mechanical parts of Sundance's revamp anyway:

I was rather fond of the original 1997 "lorry" gear gaiter, and original gear knob ...



... but finally (and after a lot of "knob" jokes from AndyM ):



I admit it does look nice with the rest of the red and black interior.

These will look very nice as well ... especially when I've swapped out the blue cloth door card inserts for black leather to match the seats. When I bought the leather seats, the door cards that came with them had been painted white so I'm going to re-colour the leather on some cream door cards from a V6.



S

Sundance getting a thorough clean before the Jap Performance Show in Coventry tomorrow. Next year, Butch, next year ...




Washed, wheels cleaned and dirt picked out of the sidelights; crap taken out the boot, interior hoovered, leather cleaned & conditioned, vinyl and plastics conditioned, new air fresheners in (strawberry) ... if only you could smell this picture




Who will blink first?



S

I should come and leave Anti for "reconditioning" to you!

Good work with the cars!
What are your plans for the side repeaters?
Modding??

The side repeaters on Sundance? Staying standard. Of course

I might change Butch's to clear ones.

Meanwhile:



Roll on cat no. 6 at next MOT. Probably ... Not sure what's causing it, but hopefully when I overhaul Sundance I can find out.

S

Hmmm, things are getting bad now!! I'm starting to think that oil is getting in to the exhaust, thus killing the cats, but there would surely be blue smoke to indicate this?

I've heard that valve seals can cause this (or of course piston rings) but I must stress that I don't have personal experience of this, it's just what others have said about my son's car (not a Mazda).
.

Yes, I'm a little worried it's something like that - but with Butch back on the road I'll be thoroughly checking out Sundance's engine, so if something needs rebuilding, that's fine.

Never seen blue smoke or had it pointed out to me. No other smoke or strange smells from exhaust etc. I've had issues getting the idle correct, so it might just mean that the engine mixture is completely out of whack. Re the cats, the first two might have been down to an undiagnosed faulty O2 sensor that meant the cats were being overloaded (faulty sensor was diagnosed and replaced at this point). The third ... no idea why it died. The fourth one, fitted March this year, just physically broke and needed replacing so I'm now on the fifth.

I suspect it's just poor engine set-up. If it proves to be worse, it might seem more sensible to simply put in a new Z5, but this one starts & runs beautifully and has never let me down, so I'd be reluctant to replace it with an engine I don't know the history of, unless it had been completely stripped and rebuilt (as Butch's V6 engine has been).

S