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M150 Knock state goes to transient

MoTeC M1 Software Tutorial

Discussion and questions related to the course MoTeC M1 Software Tutorial


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Dear All,

When looking at knock on my car I found the Knock state sometimes changing from enabled to transient when I'm pushing the car hard on 4th gear and it might have happened on different gears not sure, according to the help of Motec M1, it says transient means( the knock control holds the previous value). When this happened the knock state kept changing from enabled to transient until I pulled off the throttle. Could someone please explain why would the state of knock change to transient and what exactly is transient state. Also I'd like to know if I purchase Motec level 2 logging , will this enable me to log the knock sensors as I'm not able to log the knock sensors , only knock error in level 1 logging is possible, only way to see knock sensors values is to open the M1tune and look on the knock sheet live and I can pause it but I can't log it. Wishing all a HAPPY AND PROSPEROUS NEW YEAR. Thank you all for the support.

N.B:Package installed is John Reed for 2JZ-GTE VVTI

Have you watched any of the webinar series on the Motec page?

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I have watched the M1tune course and also motec knock webinars, I have no problem in setting the knock control . I may have missed it but my question is , my knock control is set to enabled, why would it go to transient while driving? Also I‘m asking about level 2 logging.

According to the help (in the GPR package) for Knock Mode, "Knock control is disabled for Knock Activate Delay when an ignition cut or fuel cut event occurs. This is reflected in the Knock State".

What is the value of Knock Activate Delay in your package?

So I would say that you had an ignition cut or fuel cut while driving. This is most likely caused by an Engine Speed Limit, so I would look at that value. The engine speed limit may be imposed by traction control, gear shift, or possibly a protection limit (ie. from one of the warnings, like low oil pressure).

Yes, if you add level 2 logging, you can specify additional channels to be logged (up to 200 maximum). The default diagnostic channels from the package count toward this limit, but I've never found it really that limiting, except during package firmware development.

Thank you David for your reply.Please be advised that my knock state changes to transient not disabled . My knock activate delay is 30ms . I‘ll check all my limits as per your advice but the strange thing is the car was pulling hard in 4th gear and if there was an ignition or fuel cut, I would have felt it as the knock state kept going from enabled to transient back and forth. Also my traction was off and I don‘t have any gear limits. If there was ignition or fuel cut I would have felt it at that high rpm. I‘ll recheck the log, maybe it logged something related to ignition or fuel cut, unfortunately I don‘t have the knock state in the log so I‘ll add it for future , to see exactly when it happened . Last time when I saw it , M1tune was opened on the knock sheet and thats when I noticed it.

You may want to contact John Reed as he should provide support for your firmware package. He will probably want a trimmed log showing the problem.

Looking at the code in M1Build for the GPR package, the Knock State is made "Transient", while the activation delay timer is running. It also goes directly to the Transient state when the ignition/fuel cuts are active.

To look at ignition/fuel cuts you want to monitor the channels Ignition Output Cut Count and Fuel Output Cut Count.

Perhaps the ignition / fuel cuts could be in response to an overboost control system, or something that monitors EGTs?

BTW the channels Knock State, Knock Threshold, Knock Warning, and Ignition Cyl x Knock Level and Ignition Cyl x Trim Knock, are all transmitted over the CAN bus (0x640 for all but Knock Threshold, that is on 0x650) and can be logged in the Motec dash, so you don't necessarily need Level 2 logging in the ECU to debug this if you are connected to a dash.

Ignition Output Cut Count and Fuel Output Cut Count are also transmitted.

Dear David,

Thank you so much for your support, I really appreciate it. I don't have a Motec dash. I have checked my logs and it logged ignition output cut count and fuel output cut count, I found a couple of ignition output cut count but mainly at the end of the gear when shifting as I hit maximum rpm of 7100. The only thing I changed before the last run was the filter for fuel pressure sensor and manifold pressure sensor. I reduced the filter from 25ms to 2 ms , would this cause any problems in your opinion. I'll take the car for a couple of runs and check everything live.Hopefully I can reach what is the problem and I also contacted Motec and they advised me to send them my current package to check the setup. Hopefully I can reach a solution soon. Thank you so much for the help.Will keep you updated.

Dear David,

To keep you posted on the updates. I have tried the car again for a couple of runs and I didn't get the knock state transient condition. I don't know what triggered it the first time. I have emailed John reed racing and they advised like you that transient state is "A knock state of transient is set when there is a ignition cut or fuel cut happening. Whatever knock retard values were present when the cut started will be held till after the cut is completed".So as you have explained previously that an ignition cut or fuel cut would trigger knock state to transient. I have also emailed Motec support, they have required me to send them my setup file to check what could cause this issue and I have sent it to them but I still didn't get a reply. Anyway I have purchased level 2 logging to be able to log knock sensors levels, knock state and other sensors to be able to analyze exactly what causes the knock state to go to transient if it happened again and also I feel it is important to have knock levels monitored in my log so if I encounter any knock event , I can know which cylinder had knock and what were exactly the parameters at that knock event. Thank you David for all the support.