Success! - 400Pontiac, MSD Distributor, 6AL

[krisr]

I've finally got it running and have begun tuning (until the laptop batteries died)..

Need to play with injector opening times & squirts per cycle etc... It's running very rich at idle but autotune might help me out with a few miles of driving.....

The MSD probillet distributor does indeed need to have the wiring inverted to trigger properly, i.e. purple is (+), orange is (-). VB921 is driving the MSD 6AL, no pullup resister required. I also found the most reliable spark was given with Last Interval predictor algorithm...

Input Capture: Falling Edge
Cranking Trigger: Trigger Rise
Coil: Standard Coil
Spark Output: Going High (Inverted)
Dwell and Duration: 25.5

Does anyone have a 400 or 383 cube MS2V3 2.3x MSQ they wouldn't mind sharing? I want to compare accel & decel enrichment settings and need to get my head around it more on how each feature works.

It's a good day none-the-less!!!!!

Kris

[ChevelleFan]

Krisr,

Congrats on getting it running!

I have an MSQ from my 406 in my Success Story link in my sig. Should be at the very bottom.

Do you really need the VB921 to drive the MSD box? I was under the impression the MS could drive it directly.

-Dave

[krisr]

Uhmm i'm not entirely sure man. I just went by what the manual said really. It might not need it but I guess it really can't hurt as there isn't really any load on the driver, it's just sending logic signals out Pin36... Are you doing ignition with yours or still tweaking the fuel side of things?

How did you do your VE table in yours? Auto tune, MS Tweak, dyno or manually? It's just your bins below 2000rpm look like where mind need to be. Like I generated the table and let auto tune do it's thing for about 20 miles, noticed the part throttle & cruising bins have dropped about 20%, but i'm getting a slight hesitation as it's not tuning below 1000rpm for some reason.... Once i get this VE plotted near enough i'll start to play with the accel enrichment side..

Confidence is growing though!

[blk 02]

The reason you had to have the ingition reversed is because you used the vb921 or at least im pretty sure. you'll want to tune your idle yourself, autotune wont do that. Just keep adjusting the Ve table untill you have the highest ( low numerical value) map reading. Good job and good luck

Graham

[ChevelleFan]

Uhmm i'm not entirely sure man. I just went by what the manual said really. It might not need it but I guess it really can't hurt as there isn't really any load on the driver, it's just sending logic signals out Pin36... Are you doing ignition with yours or still tweaking the fuel side of things?

How did you do your VE table in yours? Auto tune, MS Tweak, dyno or manually? It's just your bins below 2000rpm look like where mind need to be. Like I generated the table and let auto tune do it's thing for about 20 miles, noticed the part throttle & cruising bins have dropped about 20%, but i'm getting a slight hesitation as it's not tuning below 1000rpm for some reason.... Once i get this VE plotted near enough i'll start to play with the accel enrichment side..

Confidence is growing though!

Right now my engine is apart for a cylinder head swap. But before that, I was running fuel only. I plan on doing ignition once I put it back together. I'm also mounting my Megasquirt and MSD box under my dash, so I want to make sure I get the wiring right the first time.

My table is a combination of MSTweak plus manual tuning. Autotune didn't exist yet. If you can get MSTweak to work with MS-II, I highly recommend it. My setup started with MS-I and a NBO2 and that's what I did my logging/MSTweaking with. Shortly after that, I got my MS-II and a WBO2. I imported my MS-I table and then did some manual tuning to further lean out the cruise range.

If the VB921 works for sure, I guess that's good enough for me. I'll make sure to pick one up.

-Dave

[ChevelleFan]

Uhmm i'm not entirely sure man. I just went by what the manual said really. It might not need it but I guess it really can't hurt as there isn't really any load on the driver, it's just sending logic signals out Pin36... Are you doing ignition with yours or still tweaking the fuel side of things?

How did you do your VE table in yours? Auto tune, MS Tweak, dyno or manually? It's just your bins below 2000rpm look like where mind need to be. Like I generated the table and let auto tune do it's thing for about 20 miles, noticed the part throttle & cruising bins have dropped about 20%, but i'm getting a slight hesitation as it's not tuning below 1000rpm for some reason.... Once i get this VE plotted near enough i'll start to play with the accel enrichment side..

Confidence is growing though!

Right now my engine is apart for a cylinder head swap. But before that, I was running fuel only. I plan on doing ignition once I put it back together. I'm also mounting my Megasquirt and MSD box under my dash, so I want to make sure I get the wiring right the first time.

My table is a combination of MSTweak plus manual tuning. Autotune didn't exist yet. If you can get MSTweak to work with MS-II, I highly recommend it. My setup started with MS-I and a NBO2 and that's what I did my logging/MSTweaking with. Shortly after that, I got my MS-II and a WBO2. I imported my MS-I table and then did some manual tuning to further lean out the cruise range.

If the VB921 works for sure, I guess that's good enough for me. I'll make sure to pick one up.

-Dave

[krisr]

The reason you had to have the ingition reversed is because you used the vb921 or at least im pretty sure. you'll want to tune your idle yourself, autotune wont do that. Just keep adjusting the Ve table untill you have the highest ( low numerical value) map reading. Good job and good luck

Graham

Thanks for the tips Graham. I had a bit of a head scratch session whether to populate the VB921 to drive MSD, but I was still unsure whether the processor could drive MSD directly but I opted for the safe route and bought 2 VB921's (1 spare)... No complaints yet... atleast I got rid of that HEI module I was running in between the distributor/MS2 and MSD.

[krisr]

Right now my engine is apart for a cylinder head swap. But before that, I was running fuel only. I plan on doing ignition once I put it back together. I'm also mounting my Megasquirt and MSD box under my dash, so I want to make sure I get the wiring right the first time.

I had mounted my MS2 box on the inside of the firewall with about 3/16" airgap between the firewall & ECU. Basically I used 4x 3/16" bolts with 2 nuts on each bolt so I could remove the computer by myself without having anyone hold the bolt... Good theft deterant.

My table is a combination of MSTweak plus manual tuning. Autotune didn't exist yet. If you can get MSTweak to work with MS-II, I highly recommend it. My setup started with MS-I and a NBO2 and that's what I did my logging/MSTweaking with. Shortly after that, I got my MS-II and a WBO2. I imported my MS-I table and then did some manual tuning to further lean out the cruise range.

If the VB921 works for sure, I guess that's good enough for me. I'll make sure to pick one up.

Lovely, thanks for the tips also! Yeah with all the issues I had with VB921 last year trying to get it working has sort of left me with egg on my face as I had thought i tried every combination possible with wiring & settings, but obviously not ALL

I did about 20miles yesterday after the battery in my laptop semi-charged up then it died again. AutoTune was happily mapping part throttle and cruise away. Good times!!!

[96 Comp T/A]

The MSD probillet distributor does indeed need to have the wiring inverted to trigger properly, i.e. purple is (+), orange is (-). VB921 is driving the MSD 6AL, no pullup resister required. I also found the most reliable spark was given with Last Interval predictor algorithm...


Kris

Snipped for brevity. I do have a couple of questions as I am getting ready to wire up this exact combination of parts. You say the wires on the distributror need to be inverted, but you also say that purple is + and the orange is -. According to the documentation from http://www.megasquirt.info/ms2/msd6a.htm it says that on an MSD the purple lead is the + and the green is - in the first place. Can you specify which pin on the megasquirt that you wired each msd wire color too?

[krisr]

Purple and Green I think apply to the wires on the MSD ignition unit itself from memory. On a Probillet distributor they are orange and purple striped. Dieselgeek warned me initially that he had to invert his wires so I checked wit ha scope and indeed he's right.

This is how I set mine up for an MS2:
Send Purple to Pin24, Orange to the same ground plane as MS2.
If using VB921, send pin 36 to white wire on MSD.

Megatune settings:
Input capture: Falling edge
Spark Output: Going High (Inverted)
Cranking Trigger: Trigger Rise

Be sure to have your trigger offset reasonable with Trigger Rise. 0-10BTDC is fine. Turn the distributor to get your timing marks to line up and sync with MT.

Kris