Self Learning Ignition

[jordak]

  Adam said:

  Mildman said:

Depending on how the edit works I can't see why it could not still take a signal from the knock sensor and retard the timing accordingly...I don't know how sophisticated the edit mapping is....I'm sure someone else does though.

I still don't think you get it.

The PCM after editing will work just like it did before, the program is still basically the same with all the same features. The tuner has just changed the values in the tables to suit whatever it is they've done.

So the knock sensor will work just like it did before as long as it hasn't been disabled.

<{POST_SNAPBACK}>

Unless the tuner has advanced the timing to the degree that the knock sensor can't do its job anyway

[RAPHOON]

  FatBAt said:

  RAPHOON said:

  Mildman said:

Hey all,

He goes on to say that 98RON and 100RON are not worth putting in the tank, and to stick with a servo with high fuel turnover for my 95RON.

Thanks for the info Mildman.

You should ask you contact to drive in a modified car and still stick to this statement........

Who mentioned anything about a modified car?

If you buy a stock T just to have a bit more sting than a standard car, why would you want to run it on anything else but 91. If it don't ping, yer save yourself a lot of money.

Not everyone wants a squillion horsepower.

Cheers

Different strokes for different folks.

The point being that modified cars are tuned to run on 98 and you lose some of that benefit by running a lower octane fuel.

I couldn't see the sense in buying a performance car and then running it at a lower power level/octane to save a few $'s. You can always save a lot more and buy standard XR6 instead.

[turbomuz]

Just last weekend I drove from Sydney to Canberra and back. Went down with a belly full of 95 RON and to experiment I put about 40L of 91 RON in for the return leg. My T is stock and I could not pick the difference at all. Perhaps on the dyno and down the 1/4 mile it would be noticable but in highway cruising (didn't exceed 4000 rpm) and pottering around the city in traffic there is minimal benefit in forking out for 95 RON let alone 98 RON.

Muz

[Mildman]

  Adam said:

  Mildman said:

Depending on how the edit works I can't see why it could not still take a signal from the knock sensor and retard the timing accordingly...I don't know how sophisticated the edit mapping is....I'm sure someone else does though.

I still don't think you get it.

The PCM after editing will work just like it did before, the program is still basically the same with all the same features. The tuner has just changed the values in the tables to suit whatever it is they've done.

So the knock sensor will work just like it did before as long as it hasn't been disabled.

<{POST_SNAPBACK}>

Yeah I get it now, I was just not familiar in how invasive the edit tune was, if it is only changing values in tables then I'd agree the knock sensor function would still work fine. Just means if you got some dodgy petrol that you'd be a bit down on power as the ignition retards.

That is of course assuming that the retard values in the knock sensor event tables aren't edited too....but I'd doubt they would be.

  jordak said:

Unless the tuner has advanced the timing to the degree that the knock sensor can't do its job anyway

<{POST_SNAPBACK}>

Now that's a fair point, it is theoretically possible to advance it way too far, further than the knock sensors can retard.....

Edited 07/03/06 01:03 AM by Mildman

[Mildman]

  turbomuz said:

Just last weekend I drove from Sydney to Canberra and back.  Went down with a belly full of 95 RON and to experiment I put about 40L of 91 RON in for the return leg.  My T is stock and I could not pick the difference at all.  Perhaps on the dyno and down the 1/4 mile it would be noticable but in highway cruising (didn't exceed 4000 rpm) and pottering around the city in traffic there is minimal benefit in forking out for 95 RON let alone 98 RON.

Muz

<{POST_SNAPBACK}>

Again from my cal friend, he tells me I should see at least a 5% increase in efficiency on 95 compared to 91, and the price difference at the moment?

91 is about 1.20/l 95 is may 1.27/l that's about 5.8% more expensive....so pretty close to equal.

The added benefit is the car will be a bit more powerful (5%+) and you'll get a bit better economy.

Found this ACA story about premium petrol too whilst I was trying to work out the PULP price.

http://aca.ninemsn.com.au/stories/2041.asp

[Guest newl]

The solution for me is easy. There is a sticker on the inside of my fuel door that says, "Premium unleaded only". I would imagine that using anything less would perhaps give FoMoCo a reason to invalidate my warranty.

[xr6tblueprint]

also isn't the premium unleaded a cleaner fuel and better for your engine and fuel system? that's what I was lead to believe.

[Adam]

  Mildman said:

  jordak said:

Unless the tuner has advanced the timing to the degree that the knock sensor can't do its job anyway

Now that's a fair point, it is theoretically possible to advance it way too far, further than the knock sensors can retard.....

Yes.

The PCM can only pull a set maximum amount of timing out, I think it's 12 degrees, I could be wrong on that.

So if your car still pings no matter what then your timing is a long way out.

[Mildman]

  newl said:

The solution for me is easy.  There is a sticker on the inside of my fuel door that says, "Premium unleaded only".  I would imagine that using anything less would perhaps give FoMoCo a reason to invalidate my warranty.

<{POST_SNAPBACK}>

Ah yes, but is that 95RON, 98RON, or 100RON premium?

I bet they mean 95RON, which is the petrol I think is the limit for a stock tune car.

I belive the cleaner comment is true too, and I much prefer using 95 premium over 91. (The whole reason I couldn't in the beginning was due to a fuel card problem).

The rest of my point of view is that 98/100 octance fuel is wasted on a stock XR6T. The ignition maps are not designed to be able to take advantage of the higher octane fuel, and due to the quicker expiry of higher octane fuel (about 3-5 weeks from the day it is made) it means that in the higher octane stuff, which is sold in lower volumes, goes off and the octane rating drops.

I can't actually prove this expiry of higher octane petrol though....so no one sue me here, but it makes sense.

[jordak]

  Adam said:

  Mildman said:

  jordak said:

Unless the tuner has advanced the timing to the degree that the knock sensor can't do its job anyway

Now that's a fair point, it is theoretically possible to advance it way too far, further than the knock sensors can retard.....

Yes.

The PCM can only pull a set maximum amount of timing out, I think it's 12 degrees, I could be wrong on that.

So if your car still pings no matter what then your timing is a long way out.

<{POST_SNAPBACK}>

Yep ramp up the boost, add in 20 degrees timing, make some big numbers and remove the safety net in the process, regardless of whether the knock sensors are turned on or not..............wouldn't it be nice if dyno sheets showed timing as well