RomRaider

Hello,

I've been observing a wierd behavior on Idle Ignition Timing when the AC Compressor turns off, and also when you turn the steering wheel and the Power Steering Switch turns to OFF from a previous ON state.

The Idle Timing Dips down to 4. It doesn't seem to be a compensation, it will always go to 4 for a second then back up.

The problem is, when the Timing goes so low at idle (from like 16~18 to 4, the engine hesitates/stutter, making the car vibrate)

Doing this on light throttle, enough to get it out from idle, doesn't seem to show the same behavior. So there must be a Timing table for AC OFF / Power Steering switch OFF.

Tested on AZ1G202G.

Could anyone analyze the Idle/Timing routine so we could check what's going on?

Edit: MORE INFO!

The behavior appears to happen only after 81C degrees Coolant Temperature.

80 and below, it's not active! I did some logging while the temperature was rising, and the moment it went to 81C, the issue became present.

That happened on 2 cars, so it's confirmed.

Everytime PS Switch turns to OFF or AC Compressor switch turns to OFF, the Ignition Timing goes to 4 degrees for a second then goes back up.

Edit2: EVEN MORE INFO!

AZ1J500T behavior has a very little difference; The ECT condition is the same 80-81C, The Power Steering OFF (from a previous ON state) locks to 4 degrees, still the same, however the AC compressor OFF (from a previous ON state) locks to 2 degrees instead of 4.

I'm pretty sure it's not a 2d table, since it goes from nothing to full timing lock in 1C increment (from 80 to 81)

To it might be a "Below - Over" kind of table.

"Low Timing Lock Condition (AC)" Over 80 ECT ~ 4 degrees BTDC in AZ1G202G, 2 degrees in AZ1J500T
"Low Timing Lock Condition (Power Steering)" Over 80 ECT ~ 4 degrees in both ROMs.

Also, AZ1J500T is an AT ROM, so it might have different values for AT/MT? Perhaps an A and B table 1d table for both ECT and Timing BTDC ?


Edit3: Tables found! We just need to discover the logic between them.




What I was thinking of AT/MT, in fact is AC/PS switch. I compared 2 ROMs, they seem to use the same table for AT/MT, the AT one just had different values.

There seems to be A and B values, however, not related to transmission. That's where my IDA skills ends

Above, there's the stock values for the tables in AZ1G202G.

I have tested both Temperature and Degrees BTDC, changed temp to 50C, works after 50C, changed BTDC to 12 degrees, now the timing locks at 12 degrees for a second after AC/PS switch is OFF.

Disabling that table is easy as changing temperature to something over 110C.

I have not tested the RPM condition, but should work as intended aswell.







Best regards

Attaching the log below.

First appearance of the "4 degree BTDC Timing" condition at line 85.

Below that line, after every "Power Steering Switch 1 to 0" event, that condition occurs.
Before that line, Timing was compensated by a few degrees because of the engine load change (expected to maintain idle)

Please note I was moving the steering side to side to replicate that problem, that's why the Power Steering Pump Switch was oscillating from 1 to 0.

Updated the first post. I found the tables which control that timing behavior. That solves my idle issues as I can now edit them to suit my setup.

Now the questions that still persists:

There seems to be 2 tables controlling that logic - A and B. One of them has 2 values in the table, controlling AC and Power Steering, the other one only has one value.

There's individual RPM and ECT conditions for both tables.

Maybe the other table (that has a single value), controls something else than AC and PS? What's the condition for either tables? Could someone dig that?

Either disabling it by setting a higher ECT condition or changing the values from 4 to 12 degrees, both ways solves my idle issues!

With further tests, I have concluded that disabling the logic by raising ECT Condition gives the best results.

Raising the Timing values might cause engine worse vibrations depending on the ambient temps, IATs, etc.

Raising the ECT condition to over 110C to simple disable the logic makes the transitions smooth (as per before 80C ECT before any mods).

Have defined them for a few cars now, and I noted that a few of them have the tables B completely disabled (by setting a high ECT threshold, RPMs zeroed, etc)

I still haven't discovered what activates the A condition but I wasn't able to reproduce it yet.

Here's an example for AZ1G800D -

Could you share the table addresses for AZ1G202G?

They're in the image in first post, starting at CDDBC

Thanks, missed that.

I have exactly the same problem with EDM STi 2011

AZ1J500G

How I can found this tables?

AZ1J500G is compatible with AZ1G202G - you can cross flash a AZ1G202G rom onto your ECU with no issues, as I have done.

That would be your best bet as the tables you want are already defined for AZ1G202G. Not to mention there is a lot more support for AZ1G202G out there - MerpMod, etc.

Hello!

I have been comparing the AZ1J500G and AZ1G202G roms and they are not exactly the same, in some cases they have different addresses.

I already had a black box of my AZ1J500G....

When I get the car running well, the next step is to add the MermpMod and go to SD, ALS, LC....


I'm still quite a noob, although I have made a lot of progress in my vehicle tuning and I'm polishing details, I have to learn IDA and how to find codes.

Thank you!!