knock sensor....
 

what actually happens if the std knock sensor on a turbo car detects a pink? what happens if it detects a full-on det?

does it light the check engine light or does it just happily retard like mad without telling you anything is wrong?

just wondering

Owain

thanks :D

It would make no indication to you whatsoever that this has happened, what it will do is remember that it happened and when it happened, then next time around advance the ignition at that point to try and prevent it from happening again.

retard the ignition surely?

o.

I may be wrong, but I don't think I am.

Pre-ignition (pinking) is whereby the fuel ignites whilst it's being compressed before it is meant to be ignited by the spark. The spark then kicks in and ignites what's left, which causes 2 flame fronts which causes a much more powerful explosion, and less controlled as it is no longer radiating from the spark plug as is designed to.

The reason behind advancing the ignition timing is to ensure that it is the spark igniting the fuel and not the fuel igniting under it's own heat and pressure.

The other phenomina is known as det, this is whereby all the fuel isn't ignited by the spark and later the remaining mixutre self ignites causing similar problems as with pre-ignition. There is little the ECU can do about this as it is normally caused by a weak spark, poor fuel mixture, or possibly over zealous ignition advance.

Then I could be talking complete twaddle :)

when my rallycar pinks i retard the timing...

But if you were suffering from det then this would help. Wherby your ignition is too advanced that the fuel isn't being burnt correctly by the spark (or at all) in the first instance, it then ignites a little after this under it's own heat and pressure. The symptons would appear identical.

Give me a minute, I know I read something somewhere, I just cant remember where :rolleyes:

Ok, I've found what I thought I read, it doesn't describe the process the ECU goes through, but it does talk about pre-ignition and det and the difference between the too.

http://www.hastingsmfg.com/Service%2...reignition.htm

You may be interested in this http://www.ecutek.com/tuning/ignition/ too, it's from ECUTek's website.

It's a bit late in the evening to be reading this sorta stuff unless your crazy, or GreaseMonkey, but it describes what the ECU does with it's timing maps.