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Bad Miss on Dyno


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A Little stumped on my quest to fix a misfire problem.

 Car was running 'ok' (not that there were any issues) but was not huge power. Anyways i decided i need Cams 272 BC's from stock and changed the fan setup (would overheat after some solid track racing laps.) - essentially nothing with ignition.

Car now misses or feels like a bad miss up top, after 5000 and on full boost only (not free revving or low gear full throttle off boost), happens at any temperature as in doesnt seem to be because some component is too hot.

My setup as far as ignition is
 AEM Dumb coils - all tested (sparky said one was faulty so replaced it)
 Taylor 8mm leads (made up by me). - resistance on the leads (700-900 Ohms).
 twin link ecu 3 channel ignitors (around 5-10000kms old however from different batch dates)
 NGK R5671A-8 plugs gapped at 0.8mm
AFR = around 11.8


Checked that the leads fully clip in,
checked for trigger errors, none
changed dwell, ignition, fuel still the same.
added extra earth from battery in boot
earthed the ignitor casing to the head
used di electric grease
tried smaller plug gap and cooler heat range (R5671A-9)
We changed timing electronically and didnt make any diff. Same with fuel mixtures.
cleaned out CAS

Things that i havent done

- Wiring diagram says that I need a suppressor rather close to the coils (which unless the factory loom has - I didn't wire up) - What is this and im just earthing the supply cable ?
- The new solenoid for water pump. Does it need a diode installed across it?
- No heat grease behind ignitor (old model didnt come with any) - can i just use some thermal heat paste from a computer shop ?

If you look at the yellow plot (last run) each dip is a miss, big one then small one and we back off (hence it coming down). But as you can see from plots they do seem to happen at the same place each time. and this is after we have hit full boost (get 1 bar by 3700rpm)

Also attached before and after tunes.

Other things i changed which i dont think are relevant
 New version of software
 e10 fuel from 98 octane (us 91 ?octane).
 vvti settings changed to bring it on boost faster (but we changed it back and still the same)




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Hi Shamil,

can you please post the log file up in it's llg format as per the LINK software log file please.

I need the log file capture done with all parameters selected, in other words select all parameters in the PC logger setup.

Select fasted sample rate also, for the logging either 20 or 40 hz depending on your software.



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Hi  Shamil,

are you sure that your AFR input is correct as it is showing as low as 7.3:1 which is extremely rich.

If these mixtures are correct it will be the cause of your misfire, even a CDI unit would have trouble firing a mixture that rich.

The log also show a trigger 1 error count total of 255, so you have an issue with trigger 1 also.

I have attached a screen shot with this data displayed.



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Hi Dave


First of all thank you so much for your time. I really appreciate it.


1. The AFR reading is out (I think my sensor finally gave in - LC1

2. The Trigger error counter i dont think i ever looked properly into because the tuner assured me there was no trigger issues. Wow ok so just to clarify

255. would be the max counter ? This would be reset every time you start the car ? Is there a way to manually reset this ? Also what would the main reason this would happen ? and still start etc ? Dirt ?

When looking at the maps i noticed that the base timing had changed from one tune to the other but i think the overall effect was the same.

Also it is setup as Level1(low) - but the cam angle sensor is setup as just level 1. Does the low mean it is grounding on each pulse ?

Tune 1 - Trigger Offset 205 with Ref Timing of 0

Tune 1 - Trigger Offset 215 with Ref Timing of 10

Can i program the CAS manually just to be sure ?

IF so would i do the following
Trigger setup
Multitooth /Missing
Priority - Trig 1 (Crank)

Trigger1 -
Type - Reluctor
filtering - Level1 (Low)
position - Crank
teeth - 36
missing - 2

Thanks again.


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Hi Shamil,

Those trigger errors are what happened during your log run you supplied, that is why I posted the screen shot so you could see the count and the AFR reading.

I strongly advise getting the AFR meter sorted first, as you really need to know what your AFR is doing, rich or lean mixtures can cause or add to trigger error misfiring also.

I suggest you take a look at the Trigger 1 setup ,

Repair or replace your wide band sensor.

You need to get an oscilloscope and test the polarity of you wiring to the crank trigger.

The 1JZ VVt  file is pretty solid so you need to check for other issues.



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Hi Dave

When on the dyno we unplug the lc-1 and use the wideband on there, and we have the AFR's going from 14's down to 11.8 or so on full throttle.

So i think my problem is the trigger.

When i start the car and start logging i can see the trigger counter increasing up to 255.

Besides pulling out cleaning and putting back the only other thing is replacing the sensor ?

I looked at an old log file when i was diagnosing a miss and didnt have an error count then and nothing regarding wiring of the trigger or the sensor itself has changed since then.


thanks again.


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Hi Shamil,

when running the car on the dyno do the trigger 1 errors coincide with the misfires.

Unfortunately you cant really use trigger 2 as trigger 1, if you had and issue on trigger 2 we could certainly get away with only trigger 1 and some reconfiguration work, but the other way is not a possibility, as the cam signal is only generated at half crankshaft speed.

Can you please adjust your trigger settings to replicate my attached screen shot and let me know how you go.

Your Trigger 1 and 2 arming values from 3000 rpm onwards are set at double what the original file states.

You had arming voltages all set at 7 volts.

If this works but you have some minimal Trigger 1 error counts try using filter level 2 or higher.

Really to set this arming voltage correctly you need to measure the voltage with an oscilloscope and set the arming voltage to half of what your meter reads, for example if you see 6 volts at 4000 rpm you would put a value of 3 at that set point in the table.

Let me know how you go.



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Hi David


Thought i would fill you in, well it took me a ages with quite a few hours mucking around the wrong place but it was the trigger wheel missing a tooth !!!

 I was going to use a 12 tooth setup as i couldnt fine a 36 tooth wheel (and i figured the ecu can account for it) but i ended up getting my neighbour try and weld a blob back on for the missing tooth. I hope it works as only after putting everything back together did my tuner tell me that a small difference in between teeth height and it will cause a trigger error. hmm will see in morning when i start her up :) Didnt want to pull it back off again if it wasnt an issue as im sure one of the teeth next to the one broken is slightly shorter.


I tried your changes. Could you actually explain what this screen is setting up ? Is that a threshold ? Or a 'amplifiyer' type setup - suggested by another tuner to explain it.

A larger figure will send a larger pulse through the sensor ? Or is it something else that this screen setups ?


thanks a lot Dave


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Hi Shamil,

yep the broken tooth will do that, congratulations on the find.

The Trigger arming voltage threshold is used to set at what voltage the sensor input to the ecu is deemed as a valid input.

To setup this table correctly you should have an oscilloscope and measure the peak voltage generated by the mag reluctor, the voltage you read, should then be roughly halved and this value entered into the appropriate rpm site in the arming threshold table.



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