Hi All. I am building a MPFI 383 using megasquirt V3 to control fuel and spark. I am finally at the point where I am getting the car fired up and tuned. My problem is, things don't seem to be responding correctly. My Pulsewidth is jumping all over the place, and I can't really do any useful tuning because of this. I think it might be my VR ignition trigger. I am using a standard electronic ignition distributor for spark pick up. I doublechecked all my wiring and it is OK, and the controller works as expected on the bench with stim hooked up.

I guess what I am looking for is anyone who has set up their megasquirt this way and if there is anything I should be looking out for. Thanks in advance for any advice or suggestions.

Do you have a lean burn dizzy and/or did you lock out the mechanical advance and leave the vac adv unhooked? I use a lean burn 400 dizzy to trigger my classic FAST efi in inductive pickup mode.

It is a non-lean burn unit. It worked just fine behind the classic orange box when the car was in carb mode. But now in EFI mode, the RPM is jumping wildly. It obviously may be another problem, I just wanted to see if these mopar distributor pickups are "finicky" in EFI applications, or are rock solid and I should start looking elsewhere to chase down my issues.

As an aside, I don't have the unit on lockdown, but for now I just set my timing table with all zeros, and when I get the thing working reliably, I'll lock out the distributor advance and set up a table

Two other important parts to this post:

1. It's actually megasquirt 2, with V3 main board. May not make a difference for my specific questions.

2. Another part of my question, really to anyone with EFI, is that I'm running a standard alternator (with '71 up style regulator). Are these noisy, and does that ever contribute to EFI tuning issues?

Pulsewidth will jump if the RPM signal is noisy.
The -neg of the coil is a noisy place to get an RPM signal (is that where you connected?).

Don't forget to check the MS forums for info, too.

Did you follow the instructions here when setting up your ignition wiring?

http://www.diyautotune.com/tech_articles/how_to_megasquirt_your_vintage_mopar_engine.htm

On my Holley system I had to shield the pick-up wires all the way from the pick-up and out of the distributor in order to get a clean rpm sig. The inside of a distributor is a VERY noisy place.

Also, if MS is controlling the ign and you are using a mechanical advance dist, do you have the advance locked out? I wound up using a locked MSD billet with a cap-adapt so I could re-phase the rotor so the pick-up signal was at least 10 deg in advance of the ignition signal.

Kevin

My 360 MS2 is set up through a 7 pin HEI module so the computer can control timing. I figured it was best to isolate the wiring away from the computer itself, and let the HEI do all the work. I did have to turn on some noise filtering to get a smooth RPM signal. Have you adjusted the pot on the main board? Using the VR input directly from the distributor requires some adjustment IIRC.

To answer a few questions:
Yes, I followed the mopar VR ignition setup and wiring per the DIY auto link. I also have been adjusting the pots on the 2 resistors. I kinda did it by feel (like tuning a carb!) to get the best sounding performance. I have not locked out my mechanical advance yet, but right now I have my spark table set to all zeros, and an appropriate advance offset, so the spark is behaving as it did before with the carb. Once I get things workign correctly I'll lock out the dist and start populating the advance tables.

I have not really tried adjusting any input smoothing parameters. I might play with that a bit.

Out of curiosity, how specifically did you wire up your HEI module? Are you running an HEI distributor? I am very curious.

This explains how I wired/configured the HEI.

http://www.msextra.com/doc/ms2extra/MS2-Extra_HEI.htm

Here's my stealth setup to pass emissions here