Knock retard on FD

[vxer]

Hi Guys,

Does anyone know if the FD has knock retard capability on the standard ECU (or for that matter, the APC ecu)?

Also, i coming from a piston engined car where 0 degrees of knock retard is preferable, but i seem to recall reading that FD cars always seem to read some level of knock at high boost levels?

Cheers, Paul.

[rx7veilside]

i dont think there is knock retard..most modern ecus have timing retard when knock is sensed and also adds fuel but apexi doesnt have knock retard u have to rely on the mapping

[vxer]

i dont think there is knock retard..most modern ecus have timing retard when knock is sensed and also adds fuel but apexi doesnt have knock retard u have to rely on the mapping

Wow... So if you put the wrong fuel in (i.e. too low octane - like 98 on a stock ecu), you risk damaging the engine?  

Cheers, Paul.

[Ricco_04]

simple fix to that - dont put the wrong fuel in!  :Giggle  (or remap for 95ron fuel and then you can do no worse!)

All engines will expearience some degree of knock

[vxer]

simple fix to that - dont put the wrong fuel in!  :Giggle  (or remap for 95ron fuel and then you can do no worse!)

Well, if you\'re running a stock ECU (on an imported car) you can\'t help but put the wrong fuel in, since there is no 100 octane fuel in the UK  :2eek

All engines will expearience some degree of knock

Well, the idea with a turbo car usually (i\'ve no experience with rotory engines) is to map it so that there is no knock whatsoever even at high boost. Obviously knock is pretty bad for the engine so any mapper would be remiss if they didn\'t attend to it?  :3Confused

Cheers, Paul.

[Ricco_04]

As one of the 1st and most important mods to do is a remappable ECU then you can have a choice.  101 ron fuel has never existed in the UK so this is not a problem that has just come about.

Most people want extra performance out of a remap and all of their money spent on mods which means pushing it further to the edge.  I have always been lead to belive that you will always get some form of pre-ignition but the severity (sp?) of which will be different.

People who post up here asking \'is x amount of knock ok\' are met with the usuall reply of your safe up to x and in danger above if you go above this - not you should be zero at all times.

[vxer]

People who post up here asking \'is x amount of knock ok\' are met with the usuall reply of your safe up to x and in danger above if you go above this - not you should be zero at all times.

Yes, indeed - this is the reason for this thread  :Thumbs-up  I was confused because, on a piston engine, you want 0 degrees of knock at all times. Yet i have read similar things as you on this forum and fduk...  :confused:

Cheers, Paul.

[Ricco_04]

I think (and I use the word think very strongly!  :King  ) that id depends on what internals you have.  For example on a piston engine : arp bolts, forge pistons, sleaved block etc and then these stronger components can withstand more force too.

Think we need a exp tuner to help us here!  

[nikp]

I thought piston engines advanced the ignition as much as they could, then when the knock sensor identies knock starting to happen, the ignition is retard a tad, this is then repeated so as to be effictively running as much timing advance as possible. Therefore piston engines do get knock.

Or am i wrong?

[vxer]

I thought piston engines advanced the ignition as much as they could, then when the knock sensor identies knock starting to happen, the ignition is retard a tad, this is then repeated so as to be effictively running as much timing advance as possible. Therefore piston engines do get knock.

Or am i wrong?

Well, the mapper will write the map with as advanced timing as he can before the engine starts knocking*. Then after the mapping is complete, when driving around and whatnot, if the ECU detects any knock from the sensor**, it will retard the timing until there is none.

Cheers, Paul.

*) Actually, you want to advance the timing for best power output, which might not be just below the knock threshold.

**) Knock after mapping could be caused by the wrong fuel being used, or really hot air intake temperatures etc.

[rx7veilside]

on piston cars they can withstand knock slightly more but most ecus will retard the ingintion and add more fuel as soon as unsafe knock is detected..u do have to be more carefull with rotarys as the tips can pop

[Ricco_04]

AFAIK The Apexi PFC can only alert the driver of knock and is not able to retard ignition further - is this so?

[rx7veilside]

the apexi does not have ign retard as auto ign is set at mapping stage

[bnaellis]

Stock ecu will retard timing when knock is detected.
Apexi ecu has the ability to retard timing based on preset condition, i.e certain intake temps, water temps etc, but not active retard depending on knock level. I don\'t know how the knock level works on other cars but the fd has a pretty sensitive mic that pics up noise that has nothing to do with engine knock. So you may have a knock reading of 40 or so and you are no where near detonation. So the knock sensor readings has to be taken with a pinch of salt sometimes. Stock ecu on stock cars that were run on 100octane jap fuel, run perfectly fine on 98 octane here. Your only concern is if the car is modded, if so ideally you want a standalone ecu that has been mapped properly over here.

[vxer]

Stock ecu will retard timing when knock is detected.
Apexi ecu has the ability to retard timing based on preset condition, i.e certain intake temps, water temps etc, but not active retard depending on knock level. I don\'t know how the knock level works on other cars but the fd has a pretty sensitive mic that pics up noise that has nothing to do with engine knock. So you may have a knock reading of 40 or so and you are no where near detonation. So the knock sensor readings has to be taken with a pinch of salt sometimes. Stock ecu on stock cars that were run on 100octane jap fuel, run perfectly fine on 98 octane here. Your only concern is if the car is modded, if so ideally you want a standalone ecu that has been mapped properly over here.

Thanks Brian, thats helpfull stuff!

Btw, \'normal\' cars have the same setup with a piezoelectric microphone stuck on the engine which listens for the sound of knock, but can sometimes be fooled by other noises too! :rolleyes:

I\'m going to look at a rx7 over the weekend which has a full decat exhaust running a stock ECU (i think) - should i be worried?

Cheers, Paul.