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Dear all,
I own a 2001 S60 MT 140 HP.
Last October by occasion I did full throttle in 2nd gear window down, and I could clearly hear some pinging, this "zzz" "zzz" noise, at about 4000-4500 rpm. (T=14 deg C/ 57 F) I used RON-95 (i.e. MID-RATE octane). At lower temperatures there was hardly anything audible. With windows up (and lower temp) I didn't notice any knocking
Actually, I want to understand how it is working!
My questions
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- Is this knocking behaviour @4000-4500 rpm in 2nd gear full throttle using RON-95 normal??? Should I worry or not? Why can I actually HEAR the knocking (see comment 4)?
- Who can tell me how the ECU is actually programmed with regard to octane-rate adaptation? Is it immediately reacting or is there also a integrating term? Could it be that short sudden extreme conditions (like the full throttle in 2nd) are outside the retardation band width, but because it is short are not harmfull?
- There are two knock sensors (rear and front). Can ignition be retarded for selected cylinders? or is retardation always done for ALL 5 cylinders to gether?
Comments
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1. No error messages
2. Car drives actually perfectly
3. At normal driving even full throttle acceleration in other gears, no knock audible (may be because there is a lot of other road noises at higher speeds)
4.=> THIS IS THE ONE I DON'T UNDERSTAND: Always thought that the knock sensors are much faster than I am in detecting knock and that the ECU would command to retard ignition/ enrich mixture immidately, so I would not able to actually HEAR the knocking?
Thanks very much in advance for your replies,
Dutch
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