Detonation!

[YCEE]

Does all standard ECU on skylines are equipped with a knock sensor? I know there are two knock sensors on GTRs. Did anyone know how actually these sensors work? Do they prevent pinging 100% or they just take action when pinging occurs?

[meggala]

I believe thay take action when pinging occur at least it did on my rb20 when it was on the dyno it was noticable drop nin timing
meggala

[matlowth]

I believe they retard the ignition timing by up to 4 or 5 degrees at the onset of detonation.

With the powerfc, your check engine light will flash when it's detonating - which I think's a far better option!

matt

[YCEE]

Any ideas how much timing will the ECU retard? By the way, how much power less when the ECU retards the timing?

[mrmeal]

I'm fairly sure there are two of them in r32 gts-4's, green ends in colour from memory. I always thought of the knock sensor as just a device that monitors within the engine for a certain range of frequency, which means some times it can false alarm a little bit, but the law of averages rules and the ecu reacts according to the number of knocks the knock sensor picks up. Now that is quiet obviously a plumbers diagnosis of brain surgery, but it's along the right lines isn't it? Something I'm keen to know a little bit more about, so if there are any knowledgeable people in the house, any chance of enlightening me.

[[TWUBLE]]

can someone please explain exactly what detonation is and if its good or bad? sory to ask such a dumb question but im realy new at this stuff...
thanks

[Doctor]

Detonation is VERY VERY BAD. Detonation is when fuel pre-ignites in the cylinder, causing stress on cylinders, valves etc. When intake temperatures rise or low octane fuel is present the threshold of the engine to resist detonation is lowered. For example, you raise the boost from 7 - 14psi on a standard turbo car, your intercooler is only capable of holding about 12psi. This is due to the turbo exceeding its efficiency range and also the size of the factory I/C. Once boost is wound up, the faster the turbo spins and hence the reason for excessive heat.

Hope this has been helpful. Anyone correct me if I'm wrong, I'm sure you will ya bastards. :finger:

Doc
(aka Ben)

[[TWUBLE]]

Ahhhhh thanks man... I dont think my car is doing that (not that id really know what to look out for). My boost is only somewhere between 10-12psi (bout 6 1/2 ish on the standard boost guage).
So HOPEFULLY ill be able to resist that detonation thingie haha

[Doctor]

I fortgot to add, that you will hear a sound similiar to rattling coins, coming from the engine.

Doc

[[TWUBLE]]

ahhhhh haha thanks AGAIN!! ill listen out for that. i usually have the sounds up but ill keep them off nxt time i go out and see if i hear it... is the noise real loud? also can this happen on a non-turbo? my x gf's r32 gts makes a noise similar to that but may just be her exhaust

[Doctor]

severe detonation can be loud, but some times you would never the know the car was pinging.

It can happen to any car, N/A cars have a higher threshold than turbo cars, because of higher compression due to the fact that the dont have forced induction. Also don't advance your timing to much either, as it will cause pinging with out high octane fuel.

Doc

[[TWUBLE]]

ok thanks,
I only just got the car a couple of days ago... the car yard was running it on 91 octane so im gonna run the tank dry (even tho i added some octane booster to it) and run a fuel cleaner thru it then run it on 96-98octane fuel... will that help?
also how do i advance the timing? is that a good or bad idea?

[mrmeal]

it's bad, very bad if it happens too much.

[Doctor]

Dont advance your timing until you have cleared out all that other shit in your tank and run higher octane fuel. Like 98+.

Doc

[[TWUBLE]]

how do i advance the timing and what will it do?
i must appologise again for asking dum questions ahha