MSefi.com read only forum (Jan.15,2018)

I am working on a vw sand rail that has a pertronix module and have followed the DIY instructions for wiring the Board and ignitor. I have a MSII 3.0 board running 2.92. Originally it would not give any spark, then I turned in R56 and it started up. Ignition events were not consistent. I understand that R52 and R56 need to be turned completely counter clockwise to run, but it won't run at that setting.

I am unable to get the ignition events smooth without mis-fires. Fuel is at 14.0:1 to help assure there is enough fuel and not also causing misses.

It seems to run best with R56 screwed in 1/4 turn before it kills the engine. R 52 seems to help a little and is also not all the way CCW. I do not have access to a scope.

This is driving me nuts - hope someone can help keep me sane as I have been chasing this issue for a week already.

Thanks

Have you been able to run it long enough to get a data log? If so, please include a copy of it and your MSQ to facilitate troubleshooting.

no datalog yet as one of the welds to the fuel rail leaked so as soon as that is fixed I will datalog and post it.

Thanks

Don wrote:I understand that R52 and R56 need to be turned completely counter clockwise to run, but it won't run at that setting.

That is more of a starting point - using a PerTronix as a trigger is likely to require increasing the threshold value a bit.

I'll have a look at the tune and data log when you can post them.

The tune is rough just to get it going. My map value is high at idle I believe is due to the 105 degree LSA cam causing some reversion. I was able to drive it yesterday and have not made changes to anything since then. The engine would not easily rev up much past 3000RPM and frequently coughed and popped out the exhaust. It ran better with light throttle.

I probably need to say that this project is a fresh Turbocharged 1915 VW engine. Comp Ratio 7.76:1, Cam is a 119 Webcam. Intake system uses a single 5.3L GM Throttle Body. Ignition is Pertronix with a 1k resister between the red and black wires of the ignitor in a 009 distributor that the mechanical advance is locked at 10 degrees. It uses 48lb venom injectors @ 45psi and has standard sized valves and standard springs. It does have a boost referenced fuel pressure regulator. I am using the MS relay board. Trigger offset has been done as well as TPS & AFR table calibration.

Thanks

A lot of the weirdness seems to be from acceleration enrichment. Try changing Decel Fuel Amount to 100 (it's a multiplier, so 0 is cut fuel entirely, and 100% is no fuel cut) and try raising the TPSdot threshold to 50% per second. Let me know if that helps.

Matt,

I will adjust it and see how it goes.

Thank you !

Matt,

That made a huge difference but the revs are not nice and crisp yet - I assume further tuning should clean it up. I have been tuning Today and need to figure out why the autotune without a laptop doesn't work - I have some research to do on that topic.

As far as the R52 and R56 go, I guess I can leave them where they are but am still curious as to why the engine won't run with them all the way CCW out. I also have to wonder (this is the notorious "Demon Tweak" in me talking) if the R52 / R56 settings are just getting me by with a so-so spark or how can I tell if they are optimal and if not, how to get there.

Again thanks for the assistance to get me to the next step. The suicidal tendencies are gone for now... lol

Don wrote:As far as the R52 and R56 go, I guess I can leave them where they are but am still curious as to why the engine won't run with them all the way CCW out.

Because all the way CCW causes them to only trigger when the input voltage goes negative. This works great with a sine wave signal, not so well with a 0-12 volt signal.

I also have to wonder (this is the notorious "Demon Tweak" in me talking) if the R52 / R56 settings are just getting me by with a so-so spark or how can I tell if they are optimal and if not, how to get there.

If the RPM is steady, the adjustment is good. If the RPM jumps randomly by 15% or more and back to normal - they need adjustment.