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One of the features found in both the FD 2 and FN 2 ecu’s is active knock retard. This differs from the ecu’s found in the older EP 3 and DC 5 ecu’s.

Previously in the EP 3 and DC 5 the factory knock sensor would listen and record engine knock levels but do nothing about it (Passive system)

In the new FD 2 and FN 2 the ecu’s still listen to knock levels from the knock sensor, however if knock is detected above a certain threshold the ecu will act on this by retarding ignition timing (Active system)

An example of this can be seen in the below dyno chart.



The first run shown in red is a stock FD 2.
The second run shown in blue is a stock FD 2 plus reflashed ecu (At this point the ecu has been reset and is giving maximum ignition timing)
The third run is has no changes to the car but clearly has less power due to the ecu having pulled the ignition timing back. (I suspect that the ecu is acting on knock levels picked up during the second run)

What does this mean to us

It is very important that if you are having your car dynoed that you don’t just take the readings from the first run. (I have seen this on many dyno days when time is short)
To get a true power figure you must carry out several runs until the power settles.

Why does the ecu do this

It’s probably due to fuel quality

Notes

In the second dyno run shown above, I guess you could call this the cars potential power, I suspect if the fuel quality was good enough it would make this power all the time.

This type of ecu will usually pull timing quickly and put it back slowly only if the conditions allow (this is common to all modern Subaru’s also)

This offers very good protection against engine damage



 

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BJJ IS NOT JUST FOR XMAS
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Iam still confused:confused:
 

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Civinfo's Bulb Supplier
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Any idea if the Hondata keeps these knock characteristics?

Also I have only ever used 99RON VPower, will this still affect me?
 

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the old ep3 ECU is the same.

You can see this in the hondata forum.

Only the kpro ECU don't have this. Because kpro have "fixed" timing and you control the advance or retard that you want.
 

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Old EP3/DC5 stock ECU's did have Active knock retard but was dissabled on Hondata Kpro's as has been pointed out.
New Hondata products for FN/FD2 retain auto knock retard which is a really good thing.

Makes it not so bad if you run decent fuel then get some crap stuff.:D
 
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