Emission Mot Failure.

[Meldrew]

For years my '97 Z3 1900 has scraped through the mot emission test, but this year it failed and after treatment with a cat cleaner and a new lambda sensor it failed again.
Engine is excellent, burns no oil, the car runs superbly, where do i go from here.
Could it be the injectors? The cat? it seems a common problem.
Have read previous comments but could do with advice from someone who has experience of rectifying the problem at a sensible cost.
Please if you can help, as my holiday is looming.

 

[t-tony]

Most likely it will be the cat. Did you receive a print off of the test results? They should've given you one.

Tony.

 

[Meldrew]

Did not get a print off of the results, will query, thanks Tony.

 

[t-tony]

Demand a print off they are required to give you one. Check if they tested the engine oil temperature and that it reached 80 deg. If they did not test the oil temperature it will say on the sheet "Engine oil Temp." - Not Tested. Ask them firmly to test the car properly. Reading the oil temperature puts the emission testing equipment into a different range giving old cars an opportunity to pass IF it fails the so called BET (Basic Emission) test.

Tony.

 

[Geoff Crispin]

Had the same trouble with my 1998 1.9 a few years back and told them to do what Tony has said and had no trouble since

 

[Meldrew]

Are the cats on ebay etc worth buying? I presume a new BMW cat would be very expensive?

 

[t-tony]

@Stevo7682 can you advise please?

Tony.

 

[Andyboy]

Are the cats on ebay etc worth buying? I presume a new BMW cat would be very expensive?

Yes, very. As in around £1600.

The BM Catalysts ones are about the best of the cheap ones but you will only get two or possibly three MOT's from it. The really cheap ones are junk and won't pass anything.

M43 and M44 engines are bastards for this - the cat is too far away from the engine and need a good caning to get hot enough.

 

[Pingu]

I suspect that an Italian tune-up may be required. It's my MOT tomorrow, so I'll be burning a gallon of Shell's finest in order to keep another old relic on the road .

 

[t-tony]

In my experience over the last 20 years at least, BM Cats are terrible, both in how long they work and if you can actually get one to fit. Last experience was on an E85 Z4 3 weeks ago. Avoid buying their crap at all costs.

Tony.

 

[Stevo7682]

Would have to agree with Tony on that .
Stephen.

 

[Stevo7682]

@Meldrew if you have a read through this thread this is my current thoughts on cats for m44.

Emissions M44

Hi Guys time for a story that will get to a point 🤔 ( I promise) When I bought Lynne's zed got it cheap as it had a number of serious issues but let's not diverse to much . One of the issues was it had a bit of a major starting and running fault after a bit of diagnosis ended up with the...

zroadster.org

The cat in the thread has nearly 2k under its belt last couple of months and is still performing well.
But as still new in relative terms still cannot comment on the longevity of the part.

Stephen.

 

[Ianmc]

The only solution to my M44 emissions failure 3/4 years ago was a new OEM BMW cat; tried two other aftermarket cats that were no use plus additives/Irish tune up etc. No issues since.
To illustrate, you receive as much in "part exchange" for a used OEM cat as many aftermarket cats cost; says a lot!

 

[Andyboy]

I've not yet had an issue with getting a BM catalytic converter to fit, but.....

Because of theft risk, I run a cheap crap one on mine but will be fitting the original for the MOT test as it only j-u-s-t scraped through this year.

 

[Andyboy]

The only solution to my M44 emissions failure 3/4 years ago was a new OEM BMW cat; tried two other aftermarket cats that were no use plus additives/Irish tune up etc. No issues since.
To illustrate, you receive as much in "part exchange" for a used OEM cat as many aftermarket cats cost; says a lot!

An original M44 cat is worth about £350 as scrap.

 

[bertiejaffa]

time to change your MOT tester

 

[Stevo7682]

time to change your MOT tester

 

[Ianmc]

[/QUOTE]

time to change your MOT tester

time to change your MOT tester

If you are content with a dodgy MoT, that may be so

 

[Pingu]

I suspect that an Italian tune-up may be required. It's my MOT tomorrow, so I'll be burning a gallon of Shell's finest in order to keep another old relic on the road .

Just a shame that I didn't check the bulbs

MOT man said that he was really quite shocked at me. To be honest, so was I. Four bulbs not working - FOUR.

 

[Pingu]

time to change your MOT tester

Mine only passed when the tester used the right exhaust. It failed on the left. Strange.

His probe couldn't reach the Tesla in the car park.