230TE W124 gasoline - co level too high

VAngsoe

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Hi guys,
I am new to Mercedes, but i am an old mechanic.
I´v got this 1991 230TE W124 - done about 200.000 kms. Runs like a beauty.
At MOT i did not pass, since the Co level at idle was about 3,5 percent. Its only allowed to be 0.5 percent.
As soon as it gets a litle revs, the Co level drops to 0.1 percent.
I changed air-filter and spark plugs. O2 sensor and cat are fine.
The engine sounds great even at idle.
Is there any way i can adjust the Co level at idle ?
Which sensors affect the Co - AFM - at idle ?
Tks a million guys
Vangsoe
 

BillN_33

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If all else fails - I read on a US site that you can buy an additive that will reduce the CO2 so that it get through the emissions test.........they seem to user it for "oldish" cars that have problem with their test

Stick it in about a quarter of tank of fuel........have the MOT done....reading fine.........them back to normal after it has been used

Maybe if you do a search on a few US W124 related sites

Sorry that I cannot be more specific
 

television

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Lock it into second and do a high speed run (Italian tune up) just before the test, I had to do this on my 300TE in Sweden to get it through the test at 1 year old
 

star

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This would be a 102 engine equiped with a cat and is not subject to the full cat test, it is also adjustable with a 3mm allen key.
 

Number_Cruncher

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>>This would be a 102 engine equiped with a cat and is not subject to the full cat test

I suspect the motor car isn't in the UK, and possibly isn't a UK spec car, and may be subject to defferent regulations.
 

star

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>>This would be a 102 engine equiped with a cat and is not subject to the full cat test

I suspect the motor car isn't in the UK, and possibly isn't a UK spec car, and may be subject to defferent regulations.

true. :) but still adjustable unless later ingine fitted.:(
 

Number_Cruncher

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>>but still adjustable unless later ingine fitted.

Possibly - but, the OP mentions an oxygen sensor and cat. I wouldn't expect to find any adjustment on such a car.

At about this time, cars for other countries, notably Sweden, were equipped with fuel equipment that was more advanced compared with what was available in the UK.

Perhaps the OP could clarify the situation?
 

star

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early attempts at closed loop systems were adjustable as they only bolted a cat and lamda to a standard KE system. need to know what engine is fitted. (102 or 111) :)
 

television

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The CO level should be 1,0 + or - 0.5% this will be the 102 with KE and the adjuster with the 3mm key for CO levels
 

meanie

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If it's adjustable,it will be adjusted as in the attached pic.
The aperture will be through a raised 'tower' which should have a small plastic (blue or yellow) bung in it.
 

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television

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And impossible without an exhaust analyzer
 

television

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cant use exhaust analizer due to cat, voltmeter via the dianostic socket.

All of the info that I have says on a meter, I have done them on a meter successfully
 

roofless

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it's a probe up your pipe at the mot test
 
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television

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I could do that myself.

Would I be too cheeky to ask for a howto?

Would need to know what pins on the socket and what reading on the meter.

Tony

I have never seen any reference to doing this on a volt meter and I do not see how this can be the case, you are adjusting what comes out of the exhaust, and this is where the analyzer probe sits
 

Number_Cruncher

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Star is (possibly!) right - however, it all depends exactly upon which country the car was built for - which the OP hasn't yet told us.

The mixture adjuster in KE jetronic has a much wider adjustment range than the lambda sensor, so, you do have to adjust the mixture on cat equipped KE cars, to get the mixture in the range where the lambda can control it to be around stoichometric. The voltage you're checking is effectively making sure the lambda sensor spends a certain proportion of its time at the weak end compared with the rich - it's almost like a dwell setting.

The question I have with adjustments is, what has happened to the system to require an adjustment? Unless there has been a major part replaced or if there's a fault, the adjustment will never become too far wrong. If it is a fault, it's better to fix the fault, and then check the adjustment.

The reason why one would generally adjust KE cars using a gas analyzer, is that KE plus cat was a short lived combination in the UK.
 

television

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I have never seen any O2 sensor adjustments on a KE but I will take a look as soon as I can
 


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