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Rich52

Trig1 err count and fuel cut

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Hi

I'm chasing a very intermittant fuel cut which looks like its caused by RPM limit. I've found the Trig1 err Count paramater that also increases by 2 at this same point. It also increments at other times but most of the time it doesnt cause RPM Limit & Fuel cut . The max RPM recorded seems pretty consistant at 3xRPM at about 14500 rpm, ie a real 4850rpm. My logging is limited to about 100ms and since events are less than this its hard to capture.

Is there any other diagnostic that might suggest whether its is the crank or cam sensor that is the problem? Or could something else cause it?

My old ViPec doesnt have TriggerScope however I have put an oscilloscope on both signals and they look good, not noisy and no common edge transistions. However this issue only happens maybe once or twice a day when on a track day so again hard to capture.

I'm using Mitsubishi EVO 1-6 mode.

BTW another question, the RPM Limit count seems to equal the cumulative Trig1 err Count rather than the RPM limit fuel cuts I get - is that the case?

Thanks

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Can you attach some pics of the oscilloscope captures.  Make sure it has resistor sparkplugs evo's get bad trigger errors with non-resistor plugs.  

 

15 minutes ago, Rich52 said:

BTW another question, the RPM Limit count seems to equal the cumulative Trig1 err Count rather than the RPM limit fuel cuts I get - is that the case?

No the RPM limit count should increment everytime the RPM limit status goes active.  This will likely co-incide with trigger errors as the error will create an artificially high RPM, but it should increment whenever you reach the normal limit as well.

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Hi Adam

Thanks for suggestions. I've never come across resister plugs on an EVO but I'll investigate. My garage guru has suggested changing the CAM sensor that are known to be problematic with my symptoms so I'll try that.

In the mean time here is a plot of crank (top) and cam sensors at about 5k rpm.

image.png.5c0c72832a1ff14c53a508962796ce10.png

Cheers

Rich

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That is not a Evo 1-6 trigger pattern you show on your scope there. The Evo 1-6 trigger 2 signal has 1 tooth that is high for about twice as long as the other, yours are both the same length.  It looks more like you have a Evo7-9 pattern.

Evo 1-6:

Gy4S3ei.png

 

Evo 7-9:

UeFSdY3.png

 

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Interesting, it is indeed an EVO7. It's always been mapped that way by an experienced mapper! What effect will that have and is it simply a case of changing the mode setting or would it need a complete remap for timing etc.

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You would want to check base timing with a timing light after changing trigger mode, but otherwise the ignition map should be fine.

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Thanks Adam. Given its been working for a long time like that what would advantages be of changing? (ie better accuracy/stability/noise tolerance etc). Could this be cause of Trig Errors I've seen?

I see the "Filter level" is set to 2, I couldn't find any details of the what the levels actually do so hard to know what interaction this might have too.

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Having two edges occur where the ecu doesn’t expect them is likely the cause of your trigger error and limit. 

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