Knock detect questions... (Safety boost/Knock maps)

[OEM_Z]

Bear with me for some questions as Im trying to figure out knock issues. Thanks...

How do we know when the ecu has jumped over to using the knock and timing map (safety boost)?

Is there one or two types of knock that will display on the consult guages?

Is a knock message the same as code 34?

Will the check engine light come on when the ecu is in safety boost or
has detected knock code 34? If so can Nistune be modified to do this by adding a tick box?

[Matt]

Just to make clear that knock detection is work in progress

We do several things...

Collect information from the ECU with what maps it is accessing. We read a memory address, take the information and use that to display in 'pink' which map is used. Currently only a few ECUs support this and checking yesterday looks like Z32 with both knock sensors is backwards. I've changed that for the next build

Next thing is the actual detection and report on the knock sensor screen. For each pulse gone through the filter a count will increase on this screen. Currently works for a bunch of ECUs but I cannot seem to get it going for Z32 even using different ECUs

On that note the knock DTC code I thought was '21' but there is a second knock code also. If this is reported means that one of the knock sensors is 'out of range'. They must report resistance around 500kohm. Too far out of this the DTC gets raised

I cannot get that DTC generated on my bench with Z32 but can with other ECUs so dont know whats going on there

Once I've sorted those issues out we will release Rev15 firmware to report knock count for that particular ECU also. Still working on it right now

[OEM_Z]

I was wondering if the knock sensing was working correctly... Code 21 on the Z32 is "ignition circuit" and code 34 is the "knock circuit". Im not really trying to detect or read the knock sensing. Im just trying to figure out if my Z is really pinging (knocking) or if the sensor or wiring is bad, or is it just something that needs to be fixed in Nistune.

My Z is running pretty good, and I haven't really been hearing knock but I know that each night if I check the codes I keep getting the "knock sensor" showing up even after I clear it. Now I think that one day it said code 34 and displayed "knock sensor" in the description but most of the time it seems to just says "knock sensor" but no code 34. I haven't been sure if its putting me in safety boost because I can't tell if the ecu is reverting to the knock maps.

Well I still have a question I asked previously. Does the check engine light come on when a code 34 is detected? Or the answer to that was that you could not get to DTC to work on your workbench?

Thanks for looking into these issues.

[Matt]

Just checking something, 34 as you mention is the knock code, and something like 0x21 is the hex code used in the knock register used to trigger inside the ECU

I cannot get DTC to repeat on the bench so cannot confirm if 34 will raise the check engine light (CEL). I've never monitored the CEL closely but I dare say a subset of fault codes will raise this

Strange that you are getting this code all the time. This code just means that at some stage the sensor has gone out of range. It does not mean that you are knocking or accessing the knock maps

If it keeps happening using a 500k ohm resistor in the sensors place can help determine if it is a knock sensor problem

I'll have another go at repeatnig knock codes now I have a second Z32 ECU here to try out. I'm now thinknig that perhaps the knock sensor on Z32 is a different wire to other ECUs on my bench... need to double check that one since the firmware should work

[OEM_Z]

I wanted to see if my CEL is working at all so I pulled the temp sensor connector and still no CEL. So I had a friend of mine with a Z32 who just got the nistune check to see if his CEL would come on when he pulled the temp sensor connector and he also could not get the CEL to turn on. So it appears there is something wrong with the nistune code or something.

[OEM_Z]

11: crank angle sensor circuit
12*: air flow meter circuit
13*: engine coolant temp. sensor circuit
14*: vehicle speed sensor circuit
21: ignition signal circuit
26*: boost pressure sensor
31*: ECU
32*: EGR function
33*: exhaust gas sensor circuit (left)
34: detonation sensor circuit
35*: exhaust gas temp. sensor circuit
42: fuel temp. sensor circuit
43*: throttle position sensor circuit
45*: injector leak
51*: injector circuit
53*: exhaust gas sensor circuit (right)
54: signal circuit from A/T control to ECU
55: NO malfunctions in the above

*Will cause the Check Engine light to come on under normal (MODE I) operating conditions.

[Matt]

what if you use a factory ROM chip again... getting CEL with temp sensor disconnected then?

board should make no difference as we dont muck around with the diganostic code parts of the ECU (only consult routines)

[OEM_Z]

The CEL still does not display on the cluster when it should. Unplugging 02 sensors, coolant temp sensor or anything doesn't trip the sensor. Its not only on my Z but my friend as well that has Nistune. We really need the CEL to be working as to know when something is really wrong. I wouldn't want to be boosting when the ecu is detecting faults and not displaying anything.

The other thing that was not working correctly was the map tracing/highlighting of the current map. So you can't tell which maps the ecu is accessing. I think you had the colors inverted or something. So when the ecu is accessing the fuel map it actually looks like its accessing the knock fuel map instead. I thought you had mentioned that and had it fixed but the current program is the same as far as that goes.

1991 Z32

[modulation]

The CEL still does not display on the cluster when it should. Unplugging 02 sensors, coolant temp sensor or anything doesn't trip the sensor. Its not only on my Z but my friend as well that has Nistune. We really need the CEL to be working as to know when something is really wrong. I wouldn't want to be boosting when the ecu is detecting faults and not displaying anything.

The other thing that was not working correctly was the map tracing/highlighting of the current map. So you can't tell which maps the ecu is accessing. I think you had the colors inverted or something. So when the ecu is accessing the fuel map it actually looks like its accessing the knock fuel map instead. I thought you had mentioned that and had it fixed but the current program is the same as far as that goes.

1991 Z32

I have a S13 KA24de, I believe our ECU's are pretty similar..
For me, unplugged MAF, bad CAS, and unplugged o2 sensor don't trigger the ECU Light either. I read the 240sx forums and others say the same thing..

I'm not sure what would, but I don't think it's something broken in your setup.

[OEM_Z]

On a stock Z the CEL is set off when the temp sensor is uplugged while the car is runnning. Then the aux fan is also turned on and car is in saftey boost. There is something wrong if the CEL is not turning on as it should.

[Eric]

>> On a stock Z the CEL is set off when the temp sensor is uplugged while the car is runnning

no it isn't.

the list you posted earlier is not valid for all Z32's.

afaik the only one valid for all Z32's is:

31: ECU (eg. corrupt or missing eprom)