How "self-correcting" is the ecu?

[pstrbrc]

OK, I know that the ecu can correct for opening up the intake and exhaust based on reading the O2 sensor, but what about timing? With a knock sensor, it will retard the ignition if it knocks (say because of cheap gas) but will it advance until it pings if I put better gas in? The whole question I'm working on is a more complicated question than just this, but this is the first part.

 

[BrApple]

not sure but I doubt it will advance timing until it pings. the knock sensor only works after knock happens.

the zetec was designed for regular. no need to run anything more unless you have a chip or tune that requires it.

 

[mcgarvey]

The ignition timing strategy for nearly ever OBD-II vehicle will not advance timing to the point of pinging and then back it off as you've suggested. Instead it uses a default map which is programmed at the the factory and takes into account throttle position, coolant temp, RPM, and other relevant data. It will attempt to follow this map UNLESS it detects predetonation, in which case it will retard timing in steps until it stops.

 

[pstrbrc]

Thanks. So if I do some mods on the combustion chambers to make it more knock resistant, it will not advance the timing? Good.
Part two is, how much camshaft advance will the cpu deal with?
2*?
4*?
6*?
more?


Someone recommended only advancing the intake, but that would increase overlap, if my brain is working right tonight. So I want to advance both intake and exhaust, right?

 

[BrApple]

I don't think its going to deal with any since you have a VCT zetec.

 

[pstrbrc]

I don't think its going to deal with any since you have a VCT zetec.

Um, what does that have to do with it? The exhaust vct just changes the overlap. Right?

 

[BrApple]

Um, what does that have to do with it? The exhaust vct just changes the overlap. Right?

not exactly sure but it adjusts the timing ont he exhaust cam so it acts like the old egr system the zetec use to have.

I seem to recall people saying that adjustable cam gears do not play well with the vct.

 

[SicSE]

Part two is, how much camshaft advance will the cpu deal with?

As long as it can maintain a decent idle, intake cam timing shouldn't present a problem for the PCM. Though, you'll want to find out the point at which piston-to-valve clearance becomes an issue, (if it does at all), before you go dialing in a lot of adjustment... I'd be weary of going any farther than 6° either way without knowing the specs or claying the engine. Once you know your clearance, you're best bet is to just strap it to a dyno and see what affect each adjustment has.

Someone recommended only advancing the intake, but that would increase overlap

Yes, that would increase overlap, but that's not always a bad thing... especially at higher RPM's.

The exhaust vct just changes the overlap. Right?

Any change in only one of the cams' timing will affect overlap. To NOT change overlap, you would need to either advance or retard both cams.

 

[striker2]

The Zetec is a non-interference engine so he wouldnt have to worry about piston to valve clearance.