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Ignition tuning strategy on Carberry 4.2
https://mailserver.romraider.com/forum/viewtopic.php?f=36&t=20910		 Page 1 of 1
Author:  Dead_Kenny [ Thu Nov 09, 2023 6:10 am ]
Post subject:  Ignition tuning strategy on Carberry 4.2
Hi, I quite successfully configured my Impreza WRX 2003 with a JDM EJ207 engine on stock firmware. I recently switched to Carberry 4.2, and I had questions that I didn't find answers to myself. If you share your experience or throw off links to materials that I could study, I would be INSANELY grateful.

The essence of the question is in understanding the principle of calculating the Ignition Total Timing. As far as I understand from the logs, it differs from the stock firmware, in which (to simplify):
Ignition Total Timing = (Knock Correction Advance + Ignition Base Timing) - (Feedback correction + Fine correction)

Thus, tuning strategy was: increase Ignition Base Timing or Knock Correction Advance until you reach the detonation, and step back a little.

As far as I understood from the Carberry cards, as well as from the logs of the car on it, the calculation goes differently here. It looks like it always works according to the base time, and:
Ignition Total Timing = Ignition Base Timing - (Feedback correction + Fine correction + Knock Correction Retard)

Questions
1. I understand the difference in Feedback correction and Fine correction, can someone explain in which cases Knock Correction Retard works and how it interacts with each other? As far as I can see from the logs, all three corrections are triggered at different times, in different situations and are not related to each other.
2. If I looked at the detonation in the stock map according to Feedback correction, in the case of Carberry, what should I look at? Feedback correction or Knock Correction Retard?

Many thanks to everyone who responds.
Author:  skrimshaw [ Sat Jun 15, 2024 1:39 am ]
Post subject:  Re: Ignition tuning strategy on Carberry 4.2
The main difference between the stock rom and the carberry is with the stock rom you have an advance multiplier table that will add timing to the base timing. So if your iam is at 16 then the advance table will be added to the base. If the iam drops from 16 it will also drop the advance table thus reducing the total timing.

With carberry, the total timing comes from the base table. There is no more advance table, rather it is now a table that can subtract from the base timing when a knock event occurs. So instead of adding to the timing, it is only allowed to take away from the timing.

Fine knock is a learned knock event that the ecu has detected over a long period of time and automatically reduces timing in that area to avoid knock. Feedback knock is live knock occuring.

So, hopefully to answer your question, the feedback retard table gives you the ability to dictate the amount of timing the ecu can pull per knock event. So feedback knock and knock retard work together with the table you make up.

As far as what to look at, i left the knock retard table alone and tune for zero knock anywhere. Ive done several carberry tunes and have never had an issue with knock, but in the event that there is a knock event then i think the stock tables are fine how they are to save the engine. Just dial in your base table and you'll be fine.
Author:  Dead_Kenny [ Mon Jul 01, 2024 6:30 am ]
Post subject:  Re: Ignition tuning strategy on Carberry 4.2
skrimshaw wrote:
The main difference between the stock rom and the carberry is with the stock rom you have an advance multiplier table that will add timing to the base timing. So if your iam is at 16 then the advance table will be added to the base. If the iam drops from 16 it will also drop the advance table thus reducing the total timing.

With carberry, the total timing comes from the base table. There is no more advance table, rather it is now a table that can subtract from the base timing when a knock event occurs. So instead of adding to the timing, it is only allowed to take away from the timing.

Fine knock is a learned knock event that the ecu has detected over a long period of time and automatically reduces timing in that area to avoid knock. Feedback knock is live knock occuring.

So, hopefully to answer your question, the feedback retard table gives you the ability to dictate the amount of timing the ecu can pull per knock event. So feedback knock and knock retard work together with the table you make up.

As far as what to look at, i left the knock retard table alone and tune for zero knock anywhere. Ive done several carberry tunes and have never had an issue with knock, but in the event that there is a knock event then i think the stock tables are fine how they are to save the engine. Just dial in your base table and you'll be fine.


Thanks you very much bro!
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