After ecu reads knock from the sensor it reacts with changes in fuel and timing.

What causes the differences between the following:

1. The ecu reverts back to it's naturally tuned state (e.g., flash) immediatly after the WOT pull is completed. Or,
2. When you have to reset the battery in order to run the currently tuned map? The ecu will continue to run retarded until "clrl alt deleted"

Is it the severity or frequency of the detonation?

 

Bump

I'll make the question more understandable.

When the ecu pulls timing and adds fuel from knock does it

1. Go back to normal operation after the WOT pull is done?

2. After the ecu is reset from battery disconnection?

3. Both (depends)?

Why and how?

Thanks

 

Id like to know as well.

 

The ECU ramps back the ignition timing over a matter of seconds, unless more knock is detected.

 

BTW It's the level of the knock sensor signal that is used.The sensor output is filtered so it's level represents the intensity of knock vibrations. The frequency of the filter is chosen to match the vibration response of the engine / block.
The ECU calculates retarded timing in time for the very next cylinder to fire.

Some vehicles use resonant sensors that don't need filtering, as they have a spring mass system that resonates at the appropriate frequency for the engine.

 

Yep, that was my understanding of the Evo VIII ECU. I think the Evo IX ECU is more advanced in this regard, but I have only seen snippets of information, nothing definitive yet.

l8r)

 

hi.

besides reducing timing and increasing fuel, if knock is sensed, will the stock ecu also reduce boost (assuming no manual boost controller)?

just wondering, as it seems to me that by reducing the boost the ecu could kill the knock event quickly....

todd

 

The ECU does not go back to normal operation after a hard knock. It takes "awhile" to recover. I think if you reset the ECU it does go back to normal timing immediately.

From my experience w/ using the XEDE w/ SMART, the knock thresold is pretty high. I run a constant 2V of noise w/o the ECU pulling timing. When it pulls timing it pulls hard and its not happy giving it right back. That's what is neat about the SMART system. When you start to encounter extra noise (lap after lap on the race track, heat soak, bad gas, etc) it will pull a little bit of timing in order to keep the ECU from pulling a huge amount of timing then having to wait for it to come back. Of course, if the noise is low it will add additional timing for more power. To me, SMART was the best development for an EVO up to date.