Mot Failure

[swenboy]

Hi

i have taken my 1.9 for an mot and it has failed on emissions. the garage said it need a new cat which i fitted. i took it back and it failed again, they said i should of replaced the lamda sensor as well. i did that and it still failed. i only do 5 miles a day, 4000 a year if i'm lucky . has anyone got any ideas?
cheers

[estocks]

[sticks out neck] take it for an hours drive to burn off the sooty carbon buildup from all those short journeys? [/stick neck out]

[garyw]

Agree about a long drive... use the car hard and get the engine and exhaust hot, then return to the station.... don't let them keep it hanging around cold for too long either..

garyw

[SimSimma]

I had this problem on another car, long drive should do the trick. I was also told to drive half a mile in 2nd gear at high revs then take it straight in.

[Guest]

Sounds like the usual 'We think it might be ...' diagnosis from the motor trade! Pity they don't compensate the customer for their expensive mistakes.

Does your temperature gauge warm up quickly (about half a mile) and sit in the middle of the scale? A failed thermostat will cause cold running and high emissions. Were the plugs changed recently? With such a low milage I bet your poor old car has to wait ages for any servicing work.

5 miles a day is cruelty to your car anyway, and should really be compensated for by at least 2000 mile oil change intervals, just to get the acids and moisture out, whic will wreck your engine very quickly.

The first things I would do are to check that the air filter is clean, change the spark plugs, fill up with new petrol, and give it a dose of injector cleaner. Then go for a decent drive, of about 200 miles in varied conditions, ranging from motorway to steep hills, trying to keep the engine working hard as much as you can. Holding 5000 rpm in third gear on a motorway for ten minutes would help, too.

Book an appointment to have the emissions tested again, and arrive after a 20 mile run, making sure that the test is done quickly. Too many garages test emissions on a less than hot engine. You may find that everything is now OK, but if not, take it to a place where they can do a proper diagnosis of the fault.

[swenboy]

Cheers Guys

i have spoken to someone and they reckon the butterfly on the fuel intake may not be shutting properly letting excess fuel through when it idles??
i service the car my self one a year and usually change oil twice a year

[estocks]

Cheers Guys

i have spoken to someone and they reckon the butterfly on the fuel intake may not be shutting properly letting excess fuel through when it idles??
i service the car my self one a year and usually change oil twice a year

BS that would reduce the emmisions, and increase the revs.

[britton]

Try taking the air filter out before you go, this will help to reduce the emissions

[swenboy]

tried everything but alas still the same. no faults are coming up either.
fast idle test- co max limit .300 actual 1.6
hc max limit 200 actual 526
2nd fast idle much the same

any ideas

[Tourniquet]

Just checked the emissions results from my MOT, results for comparison are

fast idle test- co max limit .200 actual 0.11 (limit seems to be different?)
hc max limit 200 actual 27

Can't offer much more help beyond that

[muppet]

I had this problem on another car, long drive should do the trick. I was also told to drive half a mile in 2nd gear at high revs then take it straight in.

this used to be part of the BMW service in the old days . as said it was done to clean things out

[garyw]

Was it a genuine Lamba sensor fitted or a General use one. ?

My nephews car had a similar situation where buying the genuine article fixed it.. the symptoms were more obvious that something was wrong as the car would hardly run...

garyw

[Big Red]

Going by your emission results, you have very high hydrocarbons.
This is down to unburnt fuel, usually faulty plug, coil or burnt valve.

You need to find out why the fuel is not being burnt.
The garage should know this by the gas readings, High HC is always down to unburnt fuel entering the exhaust.

If the cat was faulty, and the management system was working ok, your CO would drop to aroung 0.5 and wouldn't go any lower as the cat will not light to drop the cO level any lower.

Looks like you have fitted a new cat through bad diagnostics.

For the HC to be so high, it should be pretty obvious which cylinder has the misfire.

Gordon

[swenboy]

Thanks for your replies

I finally have my mot.

The outcome was the lambda sensor. The replacement part from G&S was no good .I had a genuine BMW part fitted and everything is ok.
As my good friend and boss says "buy cheap buy twice".
Shame that the 1st mot site told me it was the cat.

We live and learn

[skelters]

Shame that the 1st mot site told me it was the cat.

I'd go back and tell them that they don't know what they're talking about and demand some or all of the cash back for the cost of the cat, 2nd MOT etc or tell them you're reporting them for dodgy MOT's.

[garyw]

I'd go back and tell them that they don't know what they're talking about and demand some or all of the cash back for the cost of the cat, 2nd MOT etc or tell them you're reporting them for dodgy MOT's.

and what exactly has the faulty diagnostics got to do with the MOT test...

Yes, I'd have words about it, but the company possibly thought the cheapest (compared to engine) and most regular fault would be the cat, don't most of us ??

Down to experience for both technician and customer... IMHO but crap either way...

Swenboy, pleased its sorted....

garyw

[matchy]

I Think a faulty diagnosis has EVERYTHING to do with the MOT, After all , If I make a wrong diagnosis it costs me ! If the tester said " you car's failed the emissions " , It COULD be the cat " , That's different , But If they say it IS the cat , then why should the owner pay up ? It just isn't right. However , there is a lighter note .. my cat failed , without warning , bringing the car to a halt at the most inconvenient time .. at least now you've got a car that will be okay for a while . These catalysts are a con .. Lean burn .. that's what I say , cheers , Matchy.

[Deano1712]

I Think a faulty diagnosis has EVERYTHING to do with the MOT, After all , If I make a wrong diagnosis it costs me ! If the tester said " you car's failed the emissions " , It COULD be the cat " , That's different , But If they say it IS the cat , then why should the owner pay up ? It just isn't right. However , there is a lighter note .. my cat failed , without warning , bringing the car to a halt at the most inconvenient time .. at least now you've got a car that will be okay for a while . These catalysts are a con .. Lean burn .. that's what I say , cheers , Matchy.

I agree Matchy. The industry should have gone lean burn rather than Cats. Cats do nothing for emissions till warm and many journeys are short - the cat doesnt fire up. The above sorry tale shows the folly of trusting so-called experts

[garyw]

Matchy, your barking up the wrong tree or have misunderstood me...

The MOT and the Diagnostics are two different things..

The MOT is a test of gases under a pre-determined routine, it either fails or passes. Full stop.

The diagnosis looks to have been wrong, thats where the problem is.. by all means go and complain about the MOT, it will cost YOU a test fee and they did nothing wrong...

Also remember (and most people forget), just because the car has past an MOT doesn't even start to say the car is in good condition....
A car that has just passed an MOT can falter a service routine for various reasons.

garyw

[matchy]

Sorry garyw , You are right , If it's failed it's failed ! What I am refering to is After the test when the same garage fits a new cat and it still doesn't pass ; and then expects the owner to pay . cheers Matchy.

[Guest]

Exactly - the motor trade seldom seem able to make a proper diagnosis of a problem, and throw the customer's money away in various 'We think it may be ...' actions, without any kind of certainty.

In this case, before blaming the problem on a dead cat, the engine's basic emissions and the cat should have been checked by fitting a known good lambda probe and checking its output. A 'good' reading would prove that the engine was not running rich or inefficiently, any high emissions pointing to the cat. In this case, a 'Good' probe output would correct the emissions and point at the old probe.

This is the kind of job that a proper Bosch specialist (or a BMW Dealer)would handle easily, using good equipment, knowledge, and procedure instead of guesswork.

[estocks]

*thread hijack*
How much is a new cat, BMW want £700 IIRC.

[garyw]

This is the kind of job that a proper Bosch specialist (or a BMW Dealer)would handle easily, using good equipment, knowledge, and procedure instead of guesswork.

I agree with you Mike.. and Matchy you are correct and I agree in what you say...

I can see this sadly from both sides

You as the customer want it fixed as quickly AND as cheaply as possible...

The equipment Mike has mentioned does not come cheaply, so that particular garage may not own it, but the mechanic uses his experience and "guesses" for the want of a much better word that it is usually the cat...

You at this point are very happy that your not going to have to take it too a £95 per hour dealer with the equipment to diagnose the particular problem (keep nodding your heads guys)

However the first diagnosis is wrong, but the garage may have in good faith fitted the cat thinking 100% that it will cure the fault, however it doesn't so they have to change something else, which turns out to be unexpectedly the cure....
Have you never had a indicator lamp not working ? first choice, lamp ? or fuse ?...

How many times in your own job have you thought it would be one thing and surprisingly been another.

In my prior working life, we came up with never fitting a Cat without a new genuine lambda sensor, It cost more but we never had any comebacks or unhappy customers- that or they went elsewhere

In life quality and cost are a balance, luckily sue society is now here to make it a combined thing

garyw

PS, I got out of that business when these things started happening, prior we used to really try to do the customer a favour... but these things sometimes happen. This is all from the point that the garage was honest in the first place

[Nick]

I stood behind a guy who was ranting at a Ford service reception desk -
"You have changed the battery, the alternator, the spark plugs, the starter motor, the fuel pump, you have even taken the head off and replaced all the valves and it STILL won't start!

[Big Red]

Exactly - the motor trade seldom seem able to make a proper diagnosis of a problem, and throw the customer's money away in various 'We think it may be ...' actions, without any kind of certainty..

If that is the case, then most cars would be binned whenever they give problems.
Think you are being a bit ott with such a statement, you cannot catagorise all of the motor trade this way.
As already said, if you use a garage that does not know what they are doing or do not have the correct equipment to carry out a proper diagnosis of the problem, then you will end up paying for guess work.
Remember, cheapest is not necessarily going to be.
You have to weigh up the difference of expertise you are buying on the labour costs of say £30-£100 an hour.
You get what you pay for.

In this case, before blaming the problem on a dead cat, the engine's basic emissions and the cat should have been checked by fitting a known good lambda probe and checking its output. A 'good' reading would prove that the engine was not running rich or inefficiently, any high emissions pointing to the cat. In this case, a 'Good' probe output would correct the emissions and point at the old probe...

Most good technicians would not have to fit a known good probe, they would check the operation of the fitted one with an oscilliscope.
Most good scan tools would even be able to do this looking at the live data.
No point of checking if a known probe is working when it is just as easy to check the one already fitted

This is the kind of job that a proper Bosch specialist (or a BMW Dealer)would handle easily, using good equipment, knowledge, and procedure instead of guesswork.

Also any other decent tech with the proper equipment.

In my opinion, there are far to many people slating garages for poor quality work and wrong diagnosis of problems.

Experiance, training and equipment all cost serious money.
This investment has to be paid for.
You have to remember that you are not just paying for time taken to do a job or diagnose a fault.
You are also paying for the technical know how as well.
Same old story, if you want to pay peanuts, you will only be able to employ monkeys.

Also, if the garage said to him after the mot failure that it was the cat, without them doing any diagnosis, and he didn't pay them to check things properly, then the info they gave him was worth exactly what he paid for it, nothing.

[Robert T]

This thread seems to be turning into a rant, but I'd appreciate some clarification on this:

I always take my Z to a $tealer for its MOT (whether it be a main $tealer or a BMW Specialist/Auto Technik centre). The charge for the MOT has a set maximum, so I know what it will cost. The reason I do this is so that if there is a problem which will cause an MOT failure then if can be properly diagnosed and fixed there and then. I am not without the car and I'm not p'ing about with re-tests.

1) I know that any work will cost a bit more at the $tealer, but I have been happy with their work thus far and the guys I use don't seem to charge over the odds.

2) I read somewhere on here that with the new electronic MOTs that if a car fails any part of the test, it has to be completely re-tested (even if you don't take the car away). Is this true?

[Big Red]

This thread seems to be turning into a rant, but I'd appreciate some clarification on this:

I always take my Z to a $tealer for its MOT (whether it be a main $tealer or a BMW Specialist/Auto Technik centre). The charge for the MOT has a set maximum, so I know what it will cost. The reason I do this is so that if there is a problem which will cause an MOT failure then if can be properly diagnosed and fixed there and then. I am not without the car and I'm not p'ing about with re-tests.

1) I know that any work will cost a bit more at the $tealer, but I have been happy with their work thus far and the guys I use don't seem to charge over the odds.

2) I read somewhere on here that with the new electronic MOTs that if a car fails any part of the test, it has to be completely re-tested (even if you don't take the car away). Is this true?

Hi Robert.

I can answer your above questions.

If the car fails the mot on any minor items, (there is a list of these on display at the testing stations) but basically lights, wipers, washers and tyres, and returned before the end of the next working day, a partial retest can be carried out and no charge.
After next working day, no retest can be carried out as system will not allow it.
If it fails on anything other than "minor items, then if it leaves the station then a full test must be carried out, system will not allow a partial.
If it fails on anything other than minor items and it does not leave the station, then a partial retest can be carried out and no charge.

Mot's are now on timed slots, when a vehicle is registered for test, the check sheet produced for that vehicle has a time stamp on it.
The vehicles details are also stored on the testers smart card.
Once the test is complete, the tester has to log back in to the system and record the results to print out a failure or pass.
This failure or pass also has a time stamp on it, therefore VOSA know exactly how long each test has taken.
These times are all monitored by vosa,therefore the testing stations cannot do a 10-15 minute retest on a vehicle that should have a full test as it would flag on the system imediately.
Hope this clears things up a bit and people can understand that we do not make the rules, we just have to follow them.

Gordon

[garyw]

Only some parts of the MOT were ever available to just be re-checked, however most centres re-checked those parts, both to save you money and them time..(so they could make more money )

I have also heard that the electronic will stop the free retest parts, however many places used to do a pre-MOT check thus saving you both

garyw

[Big Red]

Only some parts of the MOT were ever available to just be re-checked, however most centres re-checked those parts, both to save you money and them time..(so they could make more money )

I have also heard that the electronic will stop the free retest parts, however many places used to do a pre-MOT check thus saving you both

garyw

This is true Gary.
The good news is that things are going to change, I think it is in October, as Vosa are introducing more items that will come into the retest bracket, and i think they are adjusting the timescale as well to around 10 days.
The bad news is the price of the test will increase slightly, (this was the anuall increase that never happened at the beginning of August) and the 10 day retest will be heavily discounted from the full fee.
So in theory,although I am only guessing at this stage as we haven't been informed yet, something along the lines of "10 day retest for around £15"

Gordon

[Robert T]

That's good to know, Big Red. Quite a few sets of rules have recently been tweaked to the general disadvantage of Joe Public. I really couldn't see why I should have to pay for a re-test if I had the work carried out there and then - and thankfully it looks like I don't. Many thanks for your advice.