MSD DIS 4 SR20DET Direct spark misfire


7 posts in this topic

Posted

Hi All, hope someone is able to help me out.

The project is a Nissan GTiR, Link LEM 3G.  I wanted to switch to direct spark so got the following

cbr 600 coil-on plugs
Plug that fit into the above
MSD DIS 4 

The car runs find under light load.
The problem I am having is a misfire under load. What I have found is that the larger the dwell number the worse the misfire.

I read that dwell had no effect when running CDI ?

When running 0.5ms I get a small missfire over 5000RPM over 14PSI
The more I turn up the dwell upto 4ms the sooner ( Less load ) the misfire happens

The Spark time is 1ms
Anyone any any advise ?

Thanks

 

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Posted

Make sure your "dwell edge" is set to falling.  Set your whole dwell table to 1.0ms

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Posted

Thanks for the input ,I just set this to falling and all dwell to 1.0ms, but the engine will not start .

 

Put is back to rising, at its start ok, but will will under load ( same as before - the higher the dwell the worse the miss )

Everything Ive read says the MSD needs rising.
 

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Posted

When you are on the g2/g3 software/firmware the edge for ignition is opposite to the newer versions (g4 / g4+).  That is why falling is correct on the g2/g3.

It is "dwell edge" on the g2/g3 vs "Spark Edge" on g4/g4+

 

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Posted

Thanks for the input ,I just set this to falling and all dwell to 1.0ms, but the engine will not start .

 

Put is back to rising, at its start ok, but will will under load ( same as before - the higher the dwell the worse the miss )

Everything Ive read says the MSD needs rising.
 

it needs to be on falling.  You will need to do base timing again as swapping edges will change timing.

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Posted

Thanks.

I'll try this when I get back from work tomorrow

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Posted (edited)

Just trying this now,

I've just done a timing calibration again and the difference when swapping from rising to falling is very small 2-5 degrees ( -120   -125 ) , Also hard to tell on the starter motor.
Fixed at 10.

Still just fires once then stalls when on falling.

What am I missing ?

** UPDATE **

Just got this working, I needed to set the dwell to 2.5ms for the MSD DIS-4 unit..
Tested by swapping to 1ms when running , and the engine stalls

 

Edited by gtir350
Fixed

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