misfire during take off

[jimmylemon]

Hi,

I have a nissan 26/30, when taking off "briskly" sometimes it will rev out fine, sometimes it backfires and doesn't appear to reach limiter. I capture a log tonight where it occurred once, if someone could possibly take a look as to the cause it would be much appreciated. I noted after it did it, I could see a red warning about limiter activated, but again it appears to be doing it too low in the rev range.

I wanted to also see if it had any trigger faults. See attached.

See log below as its 20mb, attached is ecu.

https://thelemons-my.sharepoint.com/:u:/g/personal/james_thelemons_com_au/ESo_S0TSa1BDunyaGMugVXQBp4qcINml2emIAWTx-Wd9rg?e=hR9j99

Cheers.

james_ecu.pclr

[essb00]

Looks like you are having trigger errors (as RPM would sometimes shoot up in the log). I cannot confirm though as your log did not have trigger signals included. 
'Add all' parameters in the 'Setup Logging', then save another log with the similar runs.

[Adamw]

There are 4 spots in that log where you get a trigger error and the RPM spikes very high, this trips the RPM limit.  Its always at fairly high RPM, about 7000 is earliest it happened.  

I see you have a 36-2 crank trigger with a hall effect sensor, do you know what specific sensor it is using?  

[jimmylemon]

This one here Adam:

https://www.efisolutions.com.au/zf-cherry-hall-sensor-red-m12

I did select all when going to log setup before running the log session.

It has two of these one on crank and one on ex cam

[Adamw]

Ok, so two things to try.  The first one is change the trig 1 filter level to 1.  If you are still getting trig errors with the filter reduced then I would next try a stronger pull-up resistor, these sensors get a bit slow if the pull-up isn't strong enough.  The ecu's built-in pull-up is 4.7K to 5V, ZF's datasheet recommends 1K if powered by 5V or 2.4K if powered by 12V.  Turn off the ecu pull-up when you do this.  Dont worry about the cam sensor, just the crank due to the tooth count.  

  

[jimmylemon]

Thanks Adam.

I added a 1k external resistor already but its persisted. Been an issue for a while now, see below thread, same issue still.

Ill back the filtering down and take if for another run and see what it does. If that doesn't solve it, should I just look at doing a 12 tooth instead?

 

 

[Adamw]

What is the ignition system?

[jimmylemon]

Genuine Hitachi R35 gtr coils with bpr7es plugs

[jimmylemon]

New log file after after changing trigger 1 filtering to level 1.

Log 2023-08-20 10;27;59 am.llg

Very keen to get this sorted now so ill try anything.

Can you tell me if you are still seeing misfires Adam?

[jimmylemon]

Would someone be able to please let me know how I can see potential trigger faults using the log file myself?

I just don't know where to go/what to do in pc link to for it to show that.

[Adamw]

They are pretty easy to spot in the log, you will see a big spike to high or low RPM and a step in trigger 1 error counter at the same time.  

 

I just noticed it appears to happen very close to the limiter and you have quite aggressive RPM limit settings, so it might be the harsh change in crank acceleration or a vibration from the limiter that is causing it.  It is possible under hard acceleration you may not think you are reaching the limit due to tacho delay or damping. 

Can you try it with the limiter settings changed to below as a test:

 

 

 

[jimmylemon]

Will make those changes and re-test, thank you for the screenshots and information Adam.

[jimmylemon]

Should I be using any specific PIN on the ECU for ground drain for the shielding on these sensors, or will any ECU ground suffice?

[Adamw]

Any ground is fine for the shield.  

[jimmylemon]

Hi Adam,

See below log of a run after those changes. Can you see any improvement?

aferlimiterchanges.llg

[jimmylemon]

Great, still full of trigger errors.

[Adamw]

Yeah I thought that was a long shot but worth ruling out. 

Can you try the trig 1 filtering back at level 1.  Where did the trigger wheel kit come from, or is it DIY?  Can you attach a couple of pics of the trigger set up so I can see the tooth design and sensor bracket etc.  

[jimmylemon]

Hi Adam,

 

See attached.

 

Do I just go the 12 tooth profile instead? This has been plaguing me now for the best part of 3 years.

[KennyJ]

tooth count shouldnt matter ,

i've seen those cherry sensors fail , all of those that failed had exterior damage too so no manufacturer to blaim
how much is the sensor gap ? al little tighter as per manual never hurt

[Confused]

Try rotating the sensor 90 degrees.

 

[jimmylemon]

Not sure on the air gap Kenny, I know when it was in with the tuner they mucked around with this a fair bit and it didn't help.

I'll try rotate it 90 and see what happens, can't hurt for literally 30 sec work.

Interesting video but, had no idea they looked like that inside, thought the entire base was the sensor.

Cheers.

[Adamw]

Yeah I would say the guy in the video has no idea what he is talking about, the "strip" he is showing inside is just the PCB that has all the processing electronics on it, the actual hall effect element (and sometimes the separate magnet that goes behind it) is a flat disc type component, mounted 90degs to the PCB and fitted right in the end face of the body.  There are in fact some hall effect sensors where orientation is important but these will always have a flat or groove machined down the side to show the orientation.  The common red GS100502 certainly doesnt have a directional preference.

FYI, this is what the commonly used gear tooth sensor elements look like, 8mm dia, 4mm thick as this one has the magnet built in.  Certainly not a "strip".

 

 

I do agree it is worth trying different air gaps though, with these sharp teeth it will be more sensitive to air gap than a more typical tooth shape.  The thread pitch is 1mm so try it say half turn increments each way.  

 

[jimmylemon]

Hey Adam,

Appreciate that info again.

We've mucked around with air gaps extensively. I'm just going to go back to a 12-1 for now and just see if it sorts my problem.. I have access to a balancer to try it so why not.

Are you able to give me some instructions on how to change what I have to 12-1? Like do I just need to change the trigger type in the menu and that's it? 

[koracing]

Yeah you will change the trigger in the ecu as follows:
Triggers -> Trigger Setup -> multi-tooth/missing
Trigger 1 -> Trigger 1 -> Multi-tooth position -> Crank; Tooth Count -> 12; Missing teeth -> 1

Then re-verify your sync position/trigger offset of course.