# Megasquirt skip pulses?



## fugazi885 (Aug 31, 2004)

Can anyone explain what a skip pulse is in second grade english? I got my new ms installed in the car and can't get it to start. I was running on ms1 before and set the base time to 10deg before i swapped the new board in (ms3 code 2.886) it has an audi 3a distributor I set it for falling edge, coil scheme is going high and trigger offset is 64deg. It kinda stumbles when you try to start but it almost seems like it's only firing on one hole? Any thoughts on this?


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt skip pulses? (fugazi885)*

From the Megamanual:
Skip Pulses (no_skip_pulses) is the number of ignition pulses at start-up that MegaSquirt-II (or MicroSquirt) uses to calculate the rpm before sending calculated advance signals. 
More or less how many triggers to wait for steady rpm before it does anything. On cars that crank slow at first (high comp, etc) it helps to have a few in there. Usually it doesn't matter.
If you can get it to crank, and think the fueling is in the ballpark, just rotate the distro and see if you can get it to run.


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## diceman469 (Sep 3, 2003)

*Re: Megasquirt skip pulses? (need_a_VR6)*

I've tried 3 and 1, no difference from what I can see.


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## mk1vw (Oct 17, 2007)

*Re: Megasquirt skip pulses? (fugazi885)*

how many windows does the 3A hall sender vane have?
i thought it was a 1 window distributor.
that may be your problem.


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt skip pulses? (mk1vw)*

3A should be a 4 window, only the ABA/ABF use a single.


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## mk1vw (Oct 17, 2007)

*Re: Megasquirt skip pulses? (need_a_VR6)*

true, the 3A motor doesn't have a VR wheel.


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## fugazi885 (Aug 31, 2004)

*Re: Megasquirt skip pulses? (mk1vw)*

Thanks for the replies, I think I just don't have my distributor adjusted right. Before I installed the new MS I installed the audi distributor and adjusted the timing to 10 deg BTDC while the engine was still running on MS1. I thought I was doing myself a favor at the time and could just adjust the tuning parameters to accomodate this. In another post I was told the fixed angle is adjustable but I don't see where in megatune. Is this feature only available for some code versions? I'm running code 2.886 and I downloaded megatune from DIY's site as it has the appropriate ini files already there. Do I just need to fiddle with the distributor until it runs and use the trigger wizard for the rest?


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt skip pulses? (fugazi885)*

You can change the trigger offset value instead of rotating the distro. Though I would try and get the engine running and then get out the timing light to start checking ms advance vs real advance and adjusting from there. With MS1 low-high mods I run a 60deg trigger angle and a near stock distro position.


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## fugazi885 (Aug 31, 2004)

*Re: Megasquirt skip pulses? (need_a_VR6)*

I've done some more reading in the megamanual since I have some spare time on my hands (stuck at home with the flu) and if I am understang things right, the trigger offset is to compensate for the fixed position of the distributor right? So if my distributor is at 10deg BTDC the the trigger offset should be 10?


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## [email protected] (Sep 8, 2008)

*Re: Megasquirt skip pulses? (fugazi885)*

More or less. If the distributor sends the Megasquirt a pulse at 10 degrees BTDC, the trigger offset should be 10.


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## fugazi885 (Aug 31, 2004)

*Re: Megasquirt skip pulses? ([email protected])*

I finally got to spend a little time with the car and good news, it runs







I changed the trigger offset to 10 and it fired the first try. I still have plenty of tuning to do but I'm getting there. Thanks for all your replies, the megamanual can be a little confusing at times. Someone should write one of those yellow books for dummies about it, I bet you'd make a killing


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