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Air leak in my silencer (lambda)
corrado vr6 - 30/12/13 at 07:16 PM

Hi there,

After failing IVA on lambda (however co and hc are fine) I done the method of blocking the tail pipe for a couple seconds to try and find any air leaks, it would seem that it's leaking from the rivets that hold the silencer together, so it's leaking after the cat, would this help explain my lambda reading?

My problem is its the hired exhaust supplied by MK so I don't really want to take it apart incase I damage it, however if it would be influencing my lambda then ill be sending it back, can anyone help regarding the air leak affecting lambda after the cat?

Thanks in advance
Greg

CosKev3 - 30/12/13 at 08:27 PM

I always assumed on a MOT test the Lambda reading related to how well the Lambda sensor was working!!!!

Obviously not

Be interested to know what the Lambda reading/emission actually is

britishtrident - 30/12/13 at 08:58 PM

Lambda test was introduced because people were knocking holes in exhaust tailpipes to dilute the exhaust gases to get through emission test.

On tintops where new silencers have rolled edges I often find leaks and smear exhaust fitting paste into the joints before MOT the same treatment will work in this case but it I don't think this is the primary cause of your problem.

MikeRJ - 30/12/13 at 08:58 PM

quote:
Originally posted by CosKev3
I always assumed on a MOT test the Lambda reading related to how well the Lambda sensor was working!!!!

Obviously not

Be interested to know what the Lambda reading/emission actually is


Lambda is simply the ratio of the measured air/fuel ratio to the stoichiometric air fuel ratio of the fuel being used. A lambda value of 1.0 means you are running at stoichiometric (which for petrol is approximately 14.7:1 though varies somewhat with different fuel blends).

Expressing the fuelling as Lambda rather than as an air/fuel ratio is convenient as it removes the fuel stoichiometry e.g. lambda=1.0 would be the stoichiometric point for any fuel, petrol, LPG, ethanol etc. even though the required air/fuel ratio for each fuel is different.

A number lower than 1 indicates the engine is running rich (excess of fuel), and a number greater than 1 indicates a lean condition (excess of air). However, this value can obviously be corrupted by the introduction of air into the exhaust from a leak.

CosKev3 - 9/1/14 at 08:50 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by CosKev3
I always assumed on a MOT test the Lambda reading related to how well the Lambda sensor was working!!!!

Obviously not

Be interested to know what the Lambda reading/emission actually is


Lambda is simply the ratio of the measured air/fuel ratio to the stoichiometric air fuel ratio of the fuel being used. A lambda value of 1.0 means you are running at stoichiometric (which for petrol is approximately 14.7:1 though varies somewhat with different fuel blends).

Expressing the fuelling as Lambda rather than as an air/fuel ratio is convenient as it removes the fuel stoichiometry e.g. lambda=1.0 would be the stoichiometric point for any fuel, petrol, LPG, ethanol etc. even though the required air/fuel ratio for each fuel is different.

A number lower than 1 indicates the engine is running rich (excess of fuel), and a number greater than 1 indicates a lean condition (excess of air). However, this value can obviously be corrupted by the introduction of air into the exhaust from a leak.


nice one

Thanks.

40inches - 9/1/14 at 09:06 PM

I had a problem with Lambda at one point before IVA, after days of trying to find the leak I found the because I was using a ZX12 bike silencer, and bike silencers are mounted at an upward angle, therefore they have a 3mm drainage hole in the base to let water out. DOH!