Why are there two boost maps?

[JimbobUK]

Simple one hopefully

Why is it that there is an "auto" and a "manual" boost map? Which one is primarily used by the ECU, and when / why is the other one ever used?

Many thanks,
James

[Kha0S]

Depends on if you have an automatic or manual transmission vehicle.

[JimbobUK]

Thanks...

This is interesting... So the same ECU flash can drive both an auto and manual car?

In practice it seems that both boost maps are identical.

Presumably there is a jumper etc somewhere outside the ECU (in the wiring harness) which lets the ECU know whether it is in an auto or manual?

If so, how many things does it affect?

If there were some signal which could be limited to switching the boost map then we could have two versions of boost map to switch between at our pleasure (albeit probably between engine stop / start).

[intrawrx]

funny enough, i was about to fall asleep in bed lastnight when i had exactly the same question running around in my head.

Also.. have you noticed why the 3D boost maps?

why are the targets so high?

[Kha0S]

I can prove empirically that the same ECU can drive different transmissions.

I did a 5-speed conversion on my MY02 USDM WRX 4EAT... it initially liked to throw codes where it was having AT Control signal failures, but there was a pin on the ECU that I tied to ground to convince the ECU that it was in an MT car. The TCU has been completely removed and everything's happy (except the ABS and cruise controllers ).

The really interesting part, though, is that my car, even though it's running the "MT" logic, still uses the AT boost and wastegate maps! Surprised me when I first started tuning with ecuEdit, but there appears to be some bit that the car sets during bootup that triggers it to use the AT maps in lieu of the MT maps.

/Andrew

[calvinc]

If there were some signal which could be limited to switching the boost map then we could have two versions of boost map to switch between at our pleasure (albeit probably between engine stop / start).

this is how ecutek achieve their dual-boost maps - mapswitch.

calvin.

[Houdini]

Something I've been pondering in what is the relation to Max Wastegate and Desire Boost Tables and how does boost tuning work? Is it okay to max the wastegate table and just use desire boost table?

[qoncept]

Something I've been pondering in what is the relation to Max Wastegate and Desire Boost Tables and how does boost tuning work? Is it okay to max the wastegate table and just use desire boost table?

Using 100% WG duty cycle will cause boost spikes. Having too low a duty cycle will make it take longer to reach target boost. I believe it was Cobb's site that had a pretty good overview of all the values and what they do, but it may have been somewhere else.

[FrSTi]

Something I've been pondering in what is the relation to Max Wastegate and Desire Boost Tables and how does boost tuning work? Is it okay to max the wastegate table and just use desire boost table?

The stock boost control for MT is using the following tables :
- a boost target 3D map (absolute pressure target)
- an initial duty 3D map (% solenoid duty to start with)
- a maximum duty 3D map (% solenoid not to exceed)
- a proportionnal continous compensation 2D table (% duty correction/boost delta error)
- a positive integral 2D table (% duty error learning/positive delta)
- a negative integral 2D table (% duty error leaning/negative delta)
- an atm. pressure based duty compensation 2D table
- an intake air temp. based duty compensation 2D table
- a coolant temp. based duty compensation 2D table
- a gear compensation table (based on 5 gears boost % correction, even with 6MT)

To make a long story short...
The boost target 3D map is the target (is it ?)
The initial wastegate duty is the map providing % duty applicable for a certain rpm and tps (these are the axis applicable for all 3D boost tables, even if scaling can be different), this duty is then adjusted by the Ecu to stick to the target boost, within the max duty values applicable in the other 3D, with regard to the proportionnal continous rules and to the error learned in the integrales...

On top of this basic routine, you can find some additionnal corrections, as listed above (I think most of these are explicit)...

Hope I've been clear enough (thanks god it's friday), hope this clarifies

[Houdini]

Something I've been pondering in what is the relation to Max Wastegate and Desire Boost Tables and how does boost tuning work? Is it okay to max the wastegate table and just use desire boost table?

The stock boost control for MT is using the following tables :
- a boost target 3D map (absolute pressure target)
- an initial duty 3D map (% solenoid duty to start with)
- a maximum duty 3D map (% solenoid not to exceed)
- a proportionnal continous compensation 2D table (% duty correction/boost delta error)
- a positive integral 2D table (% duty error learning/positive delta)
- a negative integral 2D table (% duty error leaning/negative delta)
- an atm. pressure based duty compensation 2D table
- an intake air temp. based duty compensation 2D table
- a coolant temp. based duty compensation 2D table
- a gear compensation table (based on 5 gears boost % correction, even with 6MT)

To make a long story short...
The boost target 3D map is the target (is it ?)
The initial wastegate duty is the map providing % duty applicable for a certain rpm and tps (these are the axis applicable for all 3D boost tables, even if scaling can be different), this duty is then adjusted by the Ecu to stick to the target boost, within the max duty values applicable in the other 3D, with regard to the proportionnal continous rules and to the error learned in the integrales...

On top of this basic routine, you can find some additionnal corrections, as listed above (I think most of these are explicit)...

Hope I've been clear enough (thanks god it's friday), hope this clarifies

wow I dont even have most of those table defined yet in ecuedit - only have max and target.

[qoncept]

Great info! Looks like I have more to look at for my STX compliance tester than I realized.

[jak]

they have diferent maps pertaining to auto & manual too
I thought it was odd too that the processor would be instructed to look at a diferent area for an auto rather then just to have one map diferent if that was what ws needed
JAK

[Houdini]

If there were some signal which could be limited to switching the boost map then we could have two versions of boost map to switch between at our pleasure (albeit probably between engine stop / start).

this is how ecutek achieve their dual-boost maps - mapswitch.

calvin.

Going to have to give this a try. I'm currently running A4SGE01C from an 4EAT in my MT 2002 USDM WRX. Not quite sure which map it is using yet?

[ECUPancakes]

If there were some signal which could be limited to switching the boost map then we could have two versions of boost map to switch between at our pleasure (albeit probably between engine stop / start).

this is how ecutek achieve their dual-boost maps - mapswitch.

calvin.

Going to have to give this a try. I'm currently running A4SGE01C from an 4EAT in my MT 2002 USDM WRX. Not quite sure which map it is using yet?

It would run the MT map, since the ECU will detect your transmission. If you look in ECU Explorer, there is a binary value called AT signal or something like that. I believe it would be 1 if you have an AT and 0 for MT.

[Freon]

The turbo dynamics maps (2D) determine how much the ECU changes duty cycle to meet your targets. The 2D maps are how far off target boost vs. how much the ECU changes WGDC to try to move towards the target.

My car has a positive integral, negative integral, and a proportional. I'm not positive how they all interact, but I think the row header is amount of pressure the system is off, in the same unit as stored in the desired/target boost map.