Best algorithm for Turbo + ITB's?

[Mr Merkava]

Hi,

I might have a problem regarding the use of Speed Density in motorcycle equipped with turbocharger and itb's.

Specs
- 1216cc engine, 1200rpm - 10500rpm
- Mitsubishi TD05HR-16G-10.5 turbocharger
- 4x42mm throttleblades from Honda CBR 1000 RR
- 4 x 630cc Siemens Deka
- MW Pro 12 2-channel CDI
- 4 x 63ml/min waterinjectors after throttleblades
- Megasquirt MS3 1.3.2
- Speed density for fuel and ignition
- Bosch 0280130085 fast MAT-sensor
- GM 3bar map-sensor. There's one PU-hose coming from each ITB to small vacuumcollector (4 -> 1) and from the other of the collector goes the MAP-signal to GM MAP-sensor.


Problem
I think I have quite steady map-signal at the moment, but we had problem in dynamometer when a VE-table tuned for 100% TPS was way too rich in a dynorun with 50% TPS like this:

100%TPS = 11.5
50%TPS = 9.4

The tuner was wondering, that how megasquirt can even work when it doesn't take note on the TPS-value. He had tuned ecus (Vipec) that had different tables for different TPS-values like 25%, 50%, 75%, 100%. I could provide any answer so I found myself with maybe a real issue in my combination that I hadn't thought before.


Solution
I've tried my best (3 days googling around the web) to find a decent solution for this problem. The options seems to be:

Hybrid Alpha-N
- SD or AN as main algorithm? SD is now 60kpa-250kpa.
- What would you suggest the scales to be? SD as 40kpa - 100kpa or am I totally on wrong tracks?
- Secondary fuel: multiplicitive, additive or blend curve?
- If blended, what is equation to use? Can I see it from my logs where the line should go?
- Multiply map on/off?
- When analysing log with Megalogviewer, should I change the AN or SD-map? Should I use the current SD-map as basis and tune the AN-map?

ITB load mode
- Seems to be best for NA
- Still a bit complicated to undestand
- Could it work with multiply map?
- Autotune would work
- Only one map to tune
- I've calculated the "ITB Load TPS Switchpoints" from my logs using TPS-values aroun 89-91kpa. The picture is attached. I used the equation to calculate the values to graph. The second graph "ITB Load at TPS Switchpoint" I don't understand yet.

Previous thread concerning this when MS2. I'm not even sure if the problem today is the same.
http://www.msextra.com/forums/viewtopic ... 01&t=30166

[Matt Cramer]

ITB mode was intended for NA motors, and I wouldn't use it here. There are three options you can use. First, have a look at this page:

http://www.msextra.com/doc/ms3/tables.html

Here's a rundown of the different options you can use.

Hybrid alpha-N: In this case, that would be done by setting the load mode to alpha-N and enabling Multiply MAP. This has the fewest settings to tune, but assumes the flow is linear with MAP, which it may not be.

Speed density with blend curve based on TPS: This may be closest to what your tuner is used to. However, instead of four (?) separate tables, there are only two, with an adjustable interpolation curve.

Combined tables: You would use one table for the primary tuning, and a second table to correct for nonlinear behavior from either the TPS or MAP sensor.

[Mr Merkava]

Ok. I will try with "Combined tables - secondary multiplicitive table".

Primary fuel load: Speed Density
Seconday fuel load: Alpha-N

As my SD-table is now basically ok, I will continue tuning the AN-table. I think this should work. I left the multiply map = on, because the SD-table has been using it. The initial AN-table is full of "100".

Actually, the basic problem was that the fuel algorithm didn't take notice on the TPS-value but with this it does. Good! I will report any result back to here.

[ArttuH]

As my SD-table is now basically ok, I will continue tuning the AN-table. I think this should work. I left the multiply map = on, because the SD-table has been using it. The initial AN-table is full of "100".

I would recommend doing that another way around. So set the initial SD table full of "100" and do actual tuning with the AN table. Once you get the AN table relatively well tuned you can make compensations for different boost levels etc. to the SD table, if needed. Even though this requires more work initially (re-tuning for AN) it will be easier and more straightforward in the end. You can get pretty good starting point for the AN table by analyzing your old logs.

Otherwise your plan looks good. Just remember to set enough load rows for low throttle openings in the AN table.

[Mr Merkava]

Some updates: the Alpha-N with "multiply map = on" has worked quite well. The transition from SD-based tuning to AN-based was more easy than I expected. I have faced one very basic question:

If: Primary fuel load = Alpha N, is my AFR-table Y-axis TPS-values? From MLV it seems to be.
If I wanted AFR-table it to be SD-based, should I switch "AFR Table load = MAP" or something else?

[suberimakuri]

How did you go with AFR Table? Change it to SD?
I can see there being parts of table off boost where AN is better determinate of load.. in practice does this not matter?

Are you still using your MAP line after throttles?
Have you had to tune SD table <100kpa much?

Be great to see msq if you get a chance to post. Cheers

[muythaibxr]

I would use table switching instead of what you are doing. That way each table directly controls the fuel goiing in instead of relying on a multiplier or similar.