zambussi
Check the catalysts - you've got 6 of them, 3 on each pipe.
To understand, whether the cat is dead, lift the car and knock on a cat with a fist (mind that the exhaust can be very hot, wait some time after driving). If the cat makes a kind of dingling noise (as if there is sand inside) - it needs replacement. If the catalyst makes no sound - it is good.
zambussi
Check the catalysts - you've got 6 of them, 3 on each pipe.
To understand, whether the cat is dead, lift the car and knock on a cat with a fist (mind that the exhaust can be very hot, wait some time after driving). If the cat makes a kind of dingling noise (as if there is sand inside) - it needs replacement. If the catalyst makes no sound - it is good.
Errmmm, MB exhausts only have 4 cats max, 2 pre cats and 2 main cats any other unit on the exhaust is a resinator or silencer. Exactly what year and model is this particular car?
Hmm, maybe I have confused it with some other V12 (not Mercedes-Benz) , I don't insist that S600 has 6 cats - I have no opportunity to check that right now.
Anyways, my advice on how to check catalysts is appropriate.
Do you have a check engine light on? Is it as loud as a backfire? Do you hear a rattling from the exhuast when under a load?
In general terms, another possibility for deceleration exhaust popping is from overly lean fuel mixture. Combustion occurs when the fuel and air molecules are within combustible ratio range for a particular combustible temperature and pressure condition. Lean fuel mixture generally burns slower, and produces hotter exhaust gases. For very lean conditions, after leaving the combustion chamber, there are still unburnt lean mixture that are still under the combustible conditions except for the lack of oxygen molecules. They take more time to burn than what is available. Once they find the oxygen molecules in the exhaust, pop they go.
Under deceleration, the throttle is closed abruptly and due to flow inertia, there is a tendency to cause a leaner condition. Hence, if the normal fuel mixture is set on the lean side in the first place, the very lean condition may be met under deceleration.
This tendency is increased if there are leaks in your exhaust since more oxygen molecules are readily available; and in the CAT, temperatures are kept high.
Hence, if the symptom still occurs after ensuring the exhaust system is sound and not leaking, you may want to consider looking at which malfunctioning component can cause a lean mixture (ie. oxygen sensor, etc). But then your CEL is not on and no codes were thrown, so maybe you don't have to go that far.
What would cause Exhaust blowback / popping when letting go of the accelerator (after revving the car) ?
I also notice a slight power loss.
Only 1 exhaust makes this popping noise.
Could you tell us the year and exact model ie; W221/220/140? if so then maybe people could give you some sensible answers. I can see from the popping on one exhaust, that the problem is on the bank that feeds that exhaust. But to go further I need the above info.
Hmm, maybe I have confused it with some other V12 (not Mercedes-Benz) , I don't insist that S600 has 6 cats - I have no opportunity to check that right now.
Anyways, my advice on how to check catalysts is appropriate.
Your advice on how to check the catalitic convertor is correct
, I don't insist that S600 has 6 cats - I have no opportunity to check that right now.
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