Is there such a thing as too much advance?

[turbovanman²]

I have been playing around with all my maps, basically adding more here, taking some away there etc. Now I know that there can be too much so when do you know, besides listening/detecting knock? Its hard to judge adjustments as its not a real number, IE your adding 10 deg's here, taking out 30 deg there?

Also, I notice the stock cals all have the same shape, "advancefromrpm1" except MP cals, I didn't see the auto one, but the MP one comes on earlier?

Is this for turbo response etc? Is good to retard timing momentarilly to aid in spool?

[t3rse]

yes...look at competent maps

Too much advance, if even not discernible, can yield low boost knock that will toast rod bearings in a heartbeat. Too much retard is really bad on your turbine. Do some research and compare good timing maps from different platforms.

[turbovanman²]

yes...look at competent maps

Too much advance, if even not discernible, can yield low boost knock that will toast rod bearings in a heartbeat. Too much retard is really bad on your turbine. Do some research and compare good timing maps from different platforms.

Yeah, thats what I am doing, just trying to find good maps to compare to. I've loaded up a few MP cals.

Just curious why they all use the same shape "advancefromrpm1" except the MP cal and why they did it this way? then added more thru the map sensor maps.

[ShelGame]

Yeah, thats what I am doing, just trying to find good maps to compare to. I've loaded up a few MP cals.

Just curious why they all use the same shape "advancefromrpm1" except the MP cal and why they did it this way? then added more thru the map sensor maps.

I wouldn't mess with that 'advancefromrpm1' table. This doesn't go directly into the advance calculation. It's part of the adaptive retard code that works in boost. The MP cals have adaptive retard disabled. Which explasins why the shape is different (maybe even flat, I can't remember now).

If you want to disable the adaptive retard, set memory address 0x811f (I called it MAPConstBoost in the older cals) to 0xff. You'll probably have to change the constant type from '8-bit value list' to 'unsigned 8-bit' to change it. I think I defined it as a checkbox ('value list') in the older cals. This constant is actually the minimum MAP required for the adaptive retard to run. If you set it to 0xFF, it will simply never run.

Since I'm sure you'll ask - adaptive retard is a little bit of code that was added for the '89 T1. It basically reduces both boost (via the WG Duty Cycle) and advance if knock is detected while in boost. But, it's very short term. It doesn't store the adaptive factor in battery backed memory (like fuel for example) and it will return to 'normal' advance and WG duty cycles very quickly once knock is gone. Adaptive retard is in EVERY turbo cal made after the '89 T1 (90+ T1, T3, T4, etc.).

It might be a good idea to disable it - at least while you're tuning - so that it doesn't confuse you.

[turbovanman²]

I did mimic the MP cal with it and the boost seem to come on faster, so I figured I'd move it closer to the left and the boost hit went flat. I'll disable it and see what happens,