R129 squeezes through its MOT

Inglewood

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Jan 1, 2009
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Location
Farnham, Surrey
Your Mercedes
Now enjoying my R129
Learning a lot today and wanted to share my info - my SL500 just got past its MOT as its emissions were quite wobbly and kept reading too high.
I 100% trust the special MB place I take my car and the intel I get from them.
So - the 2 catalytic converters look below par and might not be up to the job (they were changed before I had the car it seems)
The air mass came up with a fault a couple of times but the actual values were reading ok in real time?

The car drives beautifully but when I traffic and just moving a few yards it sometimes cuts out and needs restarting - idle seems fine at 600rpm and the M113 engine doesn’t normally suffer with the crank sensor failure I understand.

Where would you start - catalytic converter check at a proper place or replace the air mass sensor?

it’s been a busy few weeks with the old girl !!
 

LostKiwi

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Aug 25, 2006
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Midlands / Charente-Maritime
Your Mercedes
'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Learning a lot today and wanted to share my info - my SL500 just got past its MOT as its emissions were quite wobbly and kept reading too high.
I 100% trust the special MB place I take my car and the intel I get from them.
So - the 2 catalytic converters look below par and might not be up to the job (they were changed before I had the car it seems)
The air mass came up with a fault a couple of times but the actual values were reading ok in real time?

The car drives beautifully but when I traffic and just moving a few yards it sometimes cuts out and needs restarting - idle seems fine at 600rpm and the M113 engine doesn’t normally suffer with the crank sensor failure I understand.

Where would you start - catalytic converter check at a proper place or replace the air mass sensor?

it’s been a busy few weeks with the old girl !!
You mean m119 doesn't suffer from crank position sensor failure - the m113 most definitely does.

I don't know where your cats are - mine is half way down the car. It takes a great deal to get it hot enough to work.

My MOT tester is aware of this and runs it up to 3000 rpm to get heat into the cat, at which point it flies through the emissions test. If just left to idle even with the new cat fitted last year it fails.
 

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