Octane/Timing relationships

[WildHorse]

Be careful with that because you could put your borderline tables into knock

Thought the borderline tables is the lookup table and the MBT tables are timing caps.

Anyways, guess it depends how conservative/aggressive timing in the tune is. Haven't noticed any KNOCK .

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[engineermike]

So I appreciate all the scientific analysis, and how Ford presents timing in any and all scenarios.

Myself, being a simpleton, just added 2° globally.

Wow.

Can't believe the difference 2° timing makes on these engines.

This was going from 91 to 93 octane.

That's about the worst possible way to accomplish what you are trying to do.

 

[WildHorse]

That's about the worst possible way to accomplish what you are trying to do.

really, how so ?

 

[engineermike]

Thought the borderline tables is the lookup table and the MBT tables are timing caps.

The logic calculates timing at least 5 different ways. You should only modify the ones that you've affected so the others stay as accurate as possible. You could say that all 5 are "caps" but more accurately it's just doing a low-select of the 5 values.

Adding 2 deg globally might make borderline more accurate to suit the fuel, but it raised the other 4 as well so they are now all erroneous. You're fooling it into running more timing rather than using the logic how it's designed to accommodate the physical changes you've made. It's called a "calibration" because it calibrates the logic to the physical characteristics of the engine. If you have no basis for changing MBT or cylinder pressure, then you shouldn't be changing it.

Ford themselves gives us a good go-by when tuning for higher octane. The FRP Power Packs are specified for 91 octane, an increase of 4 over the stock design basis. On the Gen3 the only spark tables they change are the borderline tables. On the Gen2 they also change Pre-ignition and Cylinder pressure limits, possibly due to the lower compression ratio. They do not add globally, nor do they change the MBT. I've actually looked "under the hood" of dozens of aftermarket tunes, ranging from horrible to decent, and not a single one added timing globally.

 

[WildHorse]

Adding 2 deg globally might make borderline more accurate to suit the fuel, but it raised the other 4 as well so they are now all erroneous.

Erroneous how ? And lets stick with GEN 2 logic.
Is GLOBALLY only adding 2° to the borderline, or 2° to ALL the tables ?
I would assume globally means just that ... populating all the tables.

 

[ice445]

That's about the worst possible way to accomplish what you are trying to do.

Yeah, it's fine until it's not

Erroneous how ? And lets stick with GEN 2 logic.
Is GLOBALLY only adding 2° to the borderline, or 2° to ALL the tables ?
I would assume globally means just that ... populating all the tables.

Your fuel improvement means you should only be touching the borderline tables

 

[engineermike]

Erroneous how ?

You've added 2 deg globally, rather than just to the calculation that relates to fuel octane.

If you added 2 deg to MBT, then maybe it won't hurt anything at WOT (or maybe it will), but you've now caused error in brake torque calculation, which means the spark-torque delta ratio table output will be wrong, which means the torque modulation spark will be wrong, which brings idle control, transmission torque modulation, and dozens of others with it.

Is GLOBALLY only adding 2° to the borderline, or 2° to ALL the tables ?

If you don't know, then why are you doing it? No OEM or commercial tuner is doing it that way.

 

[K4fxd]

Is GLOBALLY only adding 2° to the borderline, or 2° to ALL the tables ?

It is adding to all tables. This "could" cause a knock event where the ECU does nothing.

 

[WildHorse]

It is adding to all tables. This "could" cause a knock event where the ECU does nothing.

Thanks.

But it'll still show in a log, or while monitoring, correct ?
I have mine set to anything more that 1° of timing being taken away do
to knock it'll light up like a christmas tree.

 

[K4fxd]

But it'll still show in a log, or while monitoring, correct ?
I have mine set to anything more that 1° of timing being taken away do
to knock it'll light up like a christmas tree.

It won't take away timing due to the table being above the knock threshold. So it will knock and the only way you would know is if you hear it or are watching the actual knock sensor feed.

I'm not saying it will happen just that it could. Get some real tuning software and raise timing the correct way is my advice.

 

[WildHorse]

or are watching the actual knock sensor feed.

That's what I'm doing. it's adding .5° to 1° timing.

 

[K4fxd]

That's what I'm doing. it's adding .5° to 1° timing.

You are probably fine.

You are lucky in Canada because I could not add 2 degrees on the shit pump gas we have

 

[WildHorse]

You are probably fine.

You are lucky in Canada because I could not add 2 degrees on the shit pump gas we have

Yeah.. I'm not to worried. Good gas ... the only benefit on paying stupid high gas prices.

Ford themselves gives us a good go-by when tuning for higher octane. The FRP Power Packs are specified for 91 octane

Which has a ton of complaints about 'pinging' on 91 octane.

 

[engineermike]

Which has a ton of complaints about 'pinging' on 91 octane.

Looks like you missed the point. They added to borderline due to higher octane. They did not change mbt (or global) because octane does not affect mbt. No other tuner does either. It’s really intuitive. You change knock resistance, so you change the borderline knock tables just like ice445 said.

 

[K4fxd]

That's what I'm doing. it's adding .5° to 1° timing.

I'm saying to watch the actual knock sensor sine wave, not if it is adding or subtracting spark.

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