S14 SR20DET knock control question?

[S1RX7]

Hi,

I'm very new to the Nistune software and slowly finding my way around it. So be gentile with me

I have searched the forum and gone through the Nistune manual and cant really find what Im looking for.

I've tuned up my S14 (SR20DET) with the knock sensor off, next I copied the primary fuel and ignition maps into the knock maps so they are the same and did another pull on the dyno and the power comes down quite a bit.
Why would this happen if the maps are the same? Is there another compensation table somewhere that's knock controlled?
If I start making a map for knock I would think it will only get worse when it flicks to the knock map?

Can I ''dull'' the knock sensor down a bit in the software so it doesn't pick up every little tick of knock?

Any help or tips would be greatly appreciated!

[PL]

Make sure you have no fault codes to start with.

Beyond that it sounds like you have an overly sensitive knock sensor. Matt is digging more parameters out all the time but at this stage we don't have a way of adjusting knock sensor sensitivity as such.

You could play around and try putting high value resistors across the sensor to deaden the response a bit. But it'd take some experimenting and they're a very sensitive device so you'd need to use very high values. I'd start at 100kohms and work your way up. Fill IGN knock maps with something like 5 degrees so if it jumps to knock maps it's really obvious.

Personally I'd disconnect it and fit a 470 - 560kohm resistor across the pins. No more knock sensor problems. It's really only used to sense if an owner has filled with "regular" fuel anyway. If you look in the timing maps it's only monitored up to about 3500rpm. Any knock due to tuning issues will usually be above this point, so won't be picked up anyway.


Pete L

[S1RX7]

Pete,
Great, thanks for your help!

Ill have to do some playing around.
Where would be the best place to buy a 470 - 560kohm resistor? Jaycar? And is it literally a matter of just unplugging the sensor and wiring the resistor into the plug?

Or can I just leave the knock sensor off in the flags? Would doing that effect other things in the software?

[PL]

Yeah you just get a 1/4W 470 or 560Kohm resistor from Jaycar, unplug the knock sensor at the plug on top of the inlet manifold and fit the resistor across the terminals. This is normally done if somebody has a dead/troublesome knock sensor that's causing a fault code to be raised and they don't wanna spash out on a new sensor.

In your case it sounds like the sensor is just a bit too sensitive and/or it's picking up mechanical noise. In which case you can just disable knock sensing in NIStune and it'll then ignore the sensor.

The difference to note here is whether you have a fault code. If there's a fault code then you cannot fix it by just unchecking the flag in NIStune. You need to do the resistor mod or replace the sensor.

PL

[S1RX7]

Cool, I have no fault codes so I think I'll just keep it unchecked and that should fix it.

I'm still interested as to why if both maps are the same (Primary and Knock) and sensors turned on it looses power?
I would have thought it could knock its head off and it would always be the same tune because the maps are the same

[Matt]

What happens is that the two maps are for switching between high and low octane fuels. If it knocks too much it will switch to knock maps and lock on. Nistune will highlight 'green' the secondary map

Either way knock sensing analysis is still active and timing will still be pulled further even on knock maps if the ECU 'thinks' knock is detected

You can adjust the 'knock sensitivity' parameter if you use the 0.17 version of Nistune. Default is about 25%. I havent played with this one yet, but you can try and reduce it to see if that stops the ECU pulling timing

Otherwise if you disconnect the knock sensor you can then untick 'knock feedback' in feedback flags and turn off the DTC code for 21 - Knock sensor (rather than doing the resistor mod since I found this is not required)

[S1RX7]

Otherwise if you disconnect the knock sensor you can then untick 'knock feedback' in feedback flags and turn off the DTC code for 21 - Knock sensor (rather than doing the resistor mod since I found this is not required)

OK. thanks Matt, I'm learning!

I had a play around with this and when I disconnect the knock sensor I get a (34) DTC code? that doesn't match up with your (21) code.
Even with the flag off it keeps coming back? Maybe I need a resistor after all?
Sorry for all the Questions, I Just want to make sure I get no Knock sensor interference, and I'm doing so the correct way?

[Matt]

Sorry 21 is ignition signal. Yes 34 is knock sensor.

In the DTC filter flags you can disable it. See attached document I put together