MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - lambda sensor

OK so after an £800 Service in June followed by £280 new down pipe & checking of cam belt tensioner in August.

Yesterday it went in for its fourth down pipe & £90 cam belt tensioner. Today it failed its MOT test due to worn front tyre & co2 reading, add to this new tyres and I'm broke.

So B&G think that the co2 emissions could be either the lambda sensor, £90 to check, or possibly engine temperature sensor. Of course to check Lambda sensor will also require replacing manifold, which is £135.

Through in new rear tyres and I have spent £1500.

B&G want £60 plus vat and fitting for new NCT 185/50 fronts, there are cheaper alternatives but I have never herd of them and had bad previous experience with cheap tyres. Also I currently have 195/50 up front, should I keep to these?

Does any one have any advice, which doesn’t involve robbing a bank?
T Graveling

Re the Lambda sensor. I read an interesting piece in Autocar last month. Bosch have confessed that Lambda sensors may not last as long as stated in the blurb. I try to post the article in the next couple of days.

Tim
tim woolcott

Development

B&G have spent an hour testing the Lambda sensor, which comes up fine; they also say that the air filter and cat are OK.

They feel it might be something wrong with the engine management or electrics in some way.

I bought it from a Rover dealer eleven months ago with a years warranty, what do you think my chances are of having them pay for it to be rectified?
T Graveling

If the car does not meet standard UK MOT requirements then this means the vehicle has defects. Subject to the wording of the warranty most items that can affect this will be covered on any half decent policy. There will usually be a non committal start from anyone doing the work as until the items at fault are identified they will not be able to comment whether the warranty covers it.

Rog
Roger Parker

cant B&G check the oxy sensor in place using the testbook computer?? all other rover dealers can. it takes 15minute to do and you dont need to remove the oxy sensor.....
dave

All engine sensor functions are accesible via Testbook, as is an overview of the engine whilst running. Doesn't always show a fault and you have to sometimes read beyond the lack of any reported fault and refer back to simple understanding of the way in which this specific engine functions.

Rog
Roger Parker

As we speak B&G is checking with the warranty company to see whether this work will be covered, some chance.

Funnily when I got home last night there was a letter from the dealer that sold the car, asking whether I would like to renew the warranty when the first year ends on 15/11. I explained my current problem with failing the MOT and they responded in a very rude manner saying that it was nothing to do with them. However the person I spoke to wanted my phone number so that he could get the original sales person to call and discuss about renewing my warranty.

I usually have a sense of humour but they must be f***ing joking.

Anyway should I take the car to a Rover dealer, whom I assume have the latest technology to find the fault, rather than B&G who have already charged an hours labour to confirm that its not the lambda sensor.

T Graveling

Get the CO2 rechecked before spending any more money. Before resubmitting for the test, make sure that you have taken the car for a good, long and most importantly, hard drive. This'll burn off any carbon build up in the cat, that is usually responsible for a 'cat failure' at MoT time.

Much much cheaper than needless hours spent chasing a fault that *may* not be there.
Rob Bell

...see HELP thread....
David

Why is the car failing, not on CO2? The aim of emmission controls is to turn petrol into CO2 and H2O and nothing more noxious.

I just checked my MOT certificate and they check CO (carbon monoxide) and HC (hydrocarbons) and Lambda (whatever that is)

Excess emissions suggest a damaged or dirty cat (follow Rob's advice above) a faulty Lamda sensor which is cheap to change if it unscrews cleanly, oil burning (expensive) or a fault in the MEMS (expensive)

It sounds to me as if a certain amount of BS is being spread around but I would hate to point the finger at B&G.

Brian

Rob Bell's advice above is sound even for non-cat cars. It is essential to have all the engine components up to full operating temperature to provide an accurate reading. Definitely get a second opinion/reading. Worthwhile getting on friendly terms with a local MoT tester (always worth the effort) as opposed to "irate punter" terms with some sales outlet as is often the case ( thus avoiding "can you bring it in Tuesday fortnight" sort of things :-)). Then ask if you can bring the car along hot to have an immediate reading taken.

Both my high mileage MG Montego Turbos would fail their MoTs on emissions alone by a fair margin if not fully up to temperature. With this in mind I arrange MoT appointments to be done immediately on my arrival following a strong run down the local dual carriageway. My favourite MoT tester is aware of my reasons for this and provides a near perfect service.

JMcF
John McFeely

>>>Before resubmitting for the test, make sure that you have taken the car for a good, long and most importantly, hard drive. This'll burn off any carbon build up in the cat, that is usually responsible for a 'cat failure' at MoT time.<<<

This is such a common problem with such a simple cure! Diesels are much worse though.

Rog
Roger Parker

Here we go, the article from Autocar pp19

"You probably thought that it was a maintenance free part. You might not even know what it does or if your car has one, but failing to have your Lambda sensor checked every two years could increase fuel consumption by 15%, say engineers at Bosch.

The warning comes from the component supplier, which produces many of the Lambda sensors fitted to modern cars.

A Lambda sensor feeds infor on exhaust gas to the engine managment system to ensure smooth running and maximum fuel economy, Although the sensors are designed to last for around 60,000 mile Bosch claims that contamination from low quality fuels or water in the combustion chambers can wreck one in a third of the time"
tim woolcott

Thank you everyone for the help and advice re emission failure and other thread re tyres.

I picked up the car from B&G and took it for probably the hardest drive it has ever had in my hands and it sailed through the MOT.

Although I had to pay for an hours labour to have the lambda sensor checked, it could have been a lot worse (apparently anything up to 12 hours) without your advice of a hard drive.

One last quick question, although the garage had my old MOT which expires on the 7/11/02 they dated it the day of test 18/10/02, do I have any chance of altering dates?
T Graveling

NO

The MOT is valid for one year from the date it took place.

Ted
Ted Newman

>The MOT is valid for one year from the date it took place.
not strictly true, the MOT is valid for a year, but can be post-dated to alow you to get it within the last month and not loose any days of your old one*, but I don't know if they can be post-dated after they are written(I am guessing no).

Will
*this info is on the back of the cert
Will Munns


Hi all,
just to echo what´s already said ; Too many good cat´s have been dumped in the dustbins at dealers and other garages due to the fact that they are "only" dirty !A broken cat that rattles due to a hard hit OR cracked due to sudden flood of water is not possible to cure but otherwise a good heating of the core is all that is needed. Hence some garages just hang the cat vertically and heat evenly on the outside with a torch until it is up to temperature. Then they let the flame quickly go thru the cat and burn all contaminations away.... In most cases the cat then is as new ! If the layers inside are not poisoned the cat will perform just as the name says = be a catalyst for the gases going thru without really wear or tear anything of the cat´s own material!

BR, Carl.
Carl Blom

yes your mot cert can be post dated and the previous one cannceled no problems at all take it back to place of issue and get it changed..that month could make all the difference
mot tester

This thread was discussed between 15/10/2002 and 23/10/2002

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.