Vaccum advance per say-how much is too much?

[turbovanman²]

Advance from RPM2, I know in the old days, we'd run at least 20 deg's advance and up to 50 deg's at cruise if running an EGR. I've been playing around, but not sure how much I can get away with safely.

When the computer uses that table, when does it use it, what are the conditions?

What does the ARARPM have to do with it? Does it add to this table? I notice at around 2000-2500, it dips down, then shoots up at 3150 rpm?

Can you flat line this table or???

Thanks guys.

[bakes]

Bump?

[ShelGame]

Advance from RPM2, I know in the old days, we'd run at least 20 deg's advance and up to 50 deg's at cruise if running an EGR. I've been playing around, but not sure how much I can get away with safely.

When the computer uses that table, when does it use it, what are the conditions?

What does the ARARPM have to do with it? Does it add to this table? I notice at around 2000-2500, it dips down, then shoots up at 3150 rpm?

Can you flat line this table or???

Thanks guys.

"Advance from RPM2" is always used. It's added to the advance from MAP table (the result of which can be positive or negative).

ARARPM is part of the MAP lookup. It basically only works at WOT and only in boost (it only works when the advance from MAP is negative, which is generally in boost only). The result is multiplied by the 2's complement of the advance from MAP table (whichever of the 3 is active), and then divided by 4 to get the actual advance from MAP value. It's complicated to understand. But, I think if you set that table to return 0x40 at all points, it would essentially make it do nothing.

[turbovanman²]

"Advance from RPM2" is always used. It's added to the advance from MAP table (the result of which can be positive or negative).

ARARPM is part of the MAP lookup. It basically only works at WOT and only in boost (it only works when the advance from MAP is negative, which is generally in boost only). The result is multiplied by the 2's complement of the advance from MAP table (whichever of the 3 is active), and then divided by 4 to get the actual advance from MAP value. It's complicated to understand. But, I think if you set that table to return 0x40 at all points, it would essentially make it do nothing.

So do we really need ARARPM? or will that just screw everything up if we flatline it?

So in vacuum, it uses the part throttle table, rpm2 to do its thing?

[ShelGame]

Ok, so I went thru the code again for this. Basically, the table I call ARAMAP is actually named incorrectly. It should be MAPMUL, the same as the T2 code. This table basically multiplies the advance based on RPM when the advance from MAP is negative. The table is scaled from 0 to 4; so a value of 0x40 in fact does nothing (scaling factor equals 1.0). A value of 0x80 scales by 2.0, etc. What this does is remove more timing when in boost at higher RPM.

This is the main reason why the 2.5 T1 WOT timing table looks like it has more timing than the P/T table.

I'm going to update the T-SMEC templates with this info so that it's more clear.

[turbovanman²]

So then if we flat line that table, it will make WOT timing easier to tune and then the timing we set the WOT table it will be what it says, +12 deg for the initial?

Thanks for digging into it.

[ShelGame]

Right, but flat line it to 0x40 (3rd dashed reference line in D-Cal). That's the scaling factor = 1.0

Also, that table should not be signed as I have it shown.

[turbovanman²]

Right, but flat line it to 0x40 (3rd dashed reference line in D-Cal). That's the scaling factor = 1.0

Also, that table should not be signed as I have it shown.

Got it,

[1BADVAN]

Right, but flat line it to 0x40 (3rd dashed reference line in D-Cal). That's the scaling factor = 1.0

Also, that table should not be signed as I have it shown.

what should it be signed and why does it matter?

[turbovanman²]

Brian - Did you see my updated flow chart for the 2.5 T1 timing (T-SMEC timing)? There is another value that affects WOT timing - MAPMUL. This is a multiplier from RPM for the advance from MAP table. In the '89 T2, this value is multiplied by both the P/T and WOT tables. But, in the '89 T1, only the WOT table gets the multiplier. And, the table is very different in shape from the T2 table. You might want to take a look at it. It's why the WOT table looks like it gives you more timing than the P/T table...

Info!!

[ShelGame]

Oops, never mind...

[Ondonti]

What exactly is the purpose of this table if the effect can be achieved in other ways? more flexibility?

[ShelGame]

How is the effect achieved in other ways? Only with a 3D table, as far as I can tell...