AX - failed annual inspection

[Jaf]

Boo. Failed on emissions, rear brakes and front indicators.

Emissions, CO 2.48. Very high, previous years been 0.28 and 0.48. Didn't do an Italian tune up as I thought she was so good she didn't need it. I'll give her a service and have found my Gunson CO tester, if it still works. Maybe pop some emissions helping stuff in the fuel tank.

Rear brakes, 0.45 and 0.74, previous year 0.50 and 0.58, so uneven now. I changed brake master cylinder last week (because had completely lost foot brakes). Hopefully just need to bleed again but did have left drum off, which is now the worst side.

Front indicators, right one threw its cover off on the way there. Think he failed the left as with a new one they wouldn't then match. I did keep on eye out for it on the road, but it's 60kms! Only 10€ per indicator so not to worry.

Kilometres went to 222222!!! Cool.

[mickthemaverick]

That is rather surprising but hopefully the bleeding will sort the brakes and the cleaner sort the emissions. Good Luck

[CitroJim]

Sorry to hear she failed Jaf

On the emissions - the cat needs to be red-hot, especially if it's an after-market replacement. I know a Saxo that suffers from this and the answer has been to remove the air filter just before the test and then thrash it to within an inch of its life on the way to the MoT station!

The problem is that the cat is a long way, relatively, from the exhaust manifold and the hot exhaust can cool quite considerably before it reaches the cat. This problem is worse on a cold, winter day.

There are three, maybe four reasons for brake imbalance:

1. Bleeding, as Mick says, to dislodge persistent air, especially if the low effort is in the wheel furthest from the master cylinder.

2. The self adjusting mechanism has stopped working correctly due to seized/stiff pivots on the levers and ratchets. This is easy to fix although the brake shoes have to be completely removed from the backplates.

3. A partially seized wheel cylinder. The cylinders are a bit more complex than most as they contain pressure regulating/load sensing elements. I've successfully cleaned and rebuilt them - Autodoc still have seal kits.

4. A leaky wheel cylinder on the low effort side causing brake fluid to contaminate the friction linings.

Balance can be reasonably checked by having the wheels in the air, spinning them and using a long stick to apply the brake. Both should stop with similar (light) application of effort on the brake pedal. Note that the engine must be running as as an exhausted servo will distort the test and result in a very large apparent imbalance!

Hope that helps... Let is know how t goes...

[Jaf]

Thanks Mick, Jim.

Got new indicators on. The local shop supplied them, quicker and cheaper than autodoc. Except they didn't come with bulbs! Old bulbs have lost their orange paint. 3€ each. Madness.

Rear left brake cylinder has started leaking. It's very slight but the brakes shoes are ruined. Was completely dry a couple of weeks ago. Sigh. Have ordered 2 new brake cylinders and new brake shoes. (I reckon once 1 goes the other cylinder will fail soon too). Shop seemed confused that I wanted new 32mm hub nuts, tried to sell me new drums as that comes with new nut. Will try the other shop in town, otherwise I can get them online.

[CitroJim]

Ahh, that'll be in then Jaf... Definitely a good plan to replace both cylinders...

Looking forward to hearing you have a new MoT

[Jaf]

Update.

Changed rear brake cylinders and shoes. Blinking spares shop closes early Friday! Grumble.

Did an Italian tune up on the way to retest. Sadly though the brakes were fine the emissions were actually worse. 3.07, was 2.68 last time (other years been 0.40, 0.28). Lambda 1.044

The weather is revolting again, hopefully have a look next week.

[CitroJim]

Sorry to hear that Jaf

If your Lambda is within tolerance and your CO emissions are still very high (and very high they are if that value is indeed CO) then it's possible the cat has failed... What's your hydrocarbon (HC) reading? Is that very high too?

I say your CO is very high given that an early AX in good condition fitted with a carburettor and no cat can almost achieve the pass figure for a catted engine.

A look at the full emissions readout would be helpful to diagnose this more fully.

A high CO reading may be caused by a misfire and be given away by a high HC reading.

My approach would be to give the engine a full service with a new air filter, new spark plugs, new HT leads and if the Lambda is out of spec. a new oxygen sensor too. Also, another cause may be a failing ignition coil causing a misfire although this would be very unusual.

Another, albeit rare, cause can be a faulty temperature sensor with makes the Injection ECU 'think' the engine is colder than it is and making the mixture a little too rich. A session of diagnostics using an ELIT or Lexia machine would soon confirm that - and confirm the correct functioning of your oxygen sensor too..

As said, sight of the full emissions readout/report would help enormously.

[Jaf]

Thanks Jim. Sadly the test never mentions HC. Only CO tickover and CO acceleration . It doesn't mention the CO limits either, but she has passed at 0.48, though its more often only been 0.17. I have 10 years of test receipts!

I noticed a bit of engine hunting at 2,000 revs when I was at the test centre. (Trying to keep the engine warm)

She failed in 2017 for the engine management light (rules changed, the light had been on at previous 2 tests). That was the oxygen sensor, which I think is also called Lambda. The faulty sensor did cause the CO to go up to 2.2.

I'll have to plug the Lexia in.

[Jaf]

I plugged the Lexia in. Doesn't show a lot, could only see live data, wouldn't let me into the other option of Oxygen Sensor ( said card missing). In live data the engine temperature looked correct and the oxygen sensor voltage was varying nicely between 0.1 and 0.8. So think the oxygen sensor is working. The mixture was -0.49 with cold engine, +0.48 with hot engine. My old CO tester showed 3%.

The engine management light is not on. There's no change is performance or fuel economy.

Spark plugs are clean, light beige, and air filter was clean.

There is some moisture dripping from the back exhaust box, at the joint. Not noticed that before.

Catalytic converters are a pretty penny.

[Stickyfinger]

Catalytic converters are a pretty penny.

and are generally very poor on an AX as unlike modern cars it is a long way from the down pipe. (so the small light modern CAT does not get adequate heat so both under performs =high Co2- and can fail in a short time)

[Jaf]

The whole exhaust is at least 11 years old, the cat looks welded in rather than clamped. The back box is newest looking, even some bits of stickers on it. Not sure whether go for a cheap universal cat, for about 30€, or a decent quality one, for about 150€. I can weld things like window bars, not exhausts though. Might be better to get the entire exhaust.

Noticed that the cam cover gasket has started weeping. It's a lovely clean engine so want to change that.

[CitroJim]

As Alasdair says and given 11 years old, I fear your old cat has seen off its full quota of nine lives

Lexia has more or less ruled out all other likely causes so a new cat should see all good again...

[Jaf]

Took exhaust off to price it locally. 400 euros! 550 in second shop. Takes 2 weeks. Plus extra 30 euro delivery fee as pipe is so long. Can get it for 150 from autodoc. (The 30 euros cheap universal cat appears to not actually be a cat, which surely is illegal!).

Put some cat cleaner in her. My gunson co tester showed 1.0 so I risked the retest, drove very hard there. Failed Co 0.77, (was 3.0 before,) but only allowed 0.50. Lambda has gone up to 1.063 though, usually between 1.011 and 1.030.

Will plug lexia in again.

[CitroJim]

Sorry to hear that Jaf The cat cleaner looks like it's helped so it's looking ever more likely to be a life0-expired cat.

Yes, no way a 30 Euro 'cat' is a proper one... Not even a kitten!

Lambda is a bit high. Might be worth a new oxygen sensor too...