How to hook up wasted spark on a V6 using VB921

turbosundance · Post by **turbosundance** » Mon May 01, 2006 10:15 am

I've only been able to find posts talking about using VB921's to run wasted spark on a 4 cylinder. I want to run wated spark on my V6 without having to use a EDIS module. Could someone give me some information how to wire this up and if it can be dont. I assume that the 6 coils are wired up in pairs with a VB921 for each coil. I see spark output A and B but what about C?

enginewrecker · Post by **enginewrecker** » Tue May 02, 2006 3:30 am

you might wanna check this
http://megasquirt.sourceforge.net/extra ... wheel.html

but better study the entire site

http://megasquirt.sourceforge.net/extra/

milosch01 · Post by **milosch01** » Thu May 04, 2006 6:24 am

I just did this on a straight-6. There is an output C, and actually more than that. I used ABC, and split the firing order using a 3-coil pack: A: 1&6, B: 5&2, C: 3&4.

turbosundance · Post by **turbosundance** » Thu May 04, 2006 8:56 am

Thanks a lot

Jon k · Post by **Jon k** » Sun May 07, 2006 9:48 am

milosch01 wrote:I just did this on a straight-6. There is an output C, and actually more than that. I used ABC, and split the firing order using a 3-coil pack: A: 1&6, B: 5&2, C: 3&4.

Miosch01 - care to snap some pictures of your board and how you mounted a heatsink etc? Also, how did you get the output wires from the VB921s to the coil packs? Did you use a connector or something?

milosch01 · Post by **milosch01** » Sun May 07, 2006 11:18 am

I mounted the transistors to the top of the case over and parallel with the DB37. I ran the 3 wires out seperate from the DB37 connection, which runs to my relay board. I used a GM weatherpack connector so I can remove the ECU from the car (which has been happening a a lot!). I didn't think I would need a heatsink, and I have yet to see those transistors get hot. I am barely now getting the fuel to work so I will have to see what happens after it actually runs for awhile. But, I ran with a single VB921 mounted this way for almost a year.

Jon k · Post by **Jon k** » Sun May 07, 2006 11:42 am

milosch01 wrote:I mounted the transistors to the top of the case over and parallel with the DB37. I ran the 3 wires out seperate from the DB37 connection, which runs to my relay board. I used a GM weatherpack connector so I can remove the ECU from the car (which has been happening a a lot!). I didn't think I would need a heatsink, and I have yet to see those transistors get hot. I am barely now getting the fuel to work so I will have to see what happens after it actually runs for awhile. But, I ran with a single VB921 mounted this way for almost a year.

So you only have 3 VB921s? I guess your coil pack is a 3 coil... I am going for 6 COP, so I need 6 VB921s... where did you get the GM weather grade connector

milosch01 · Post by **milosch01** » Sun May 07, 2006 12:56 pm

Pep Boys carries them. We also have a place called XL Parts that has them, but I have not seen them at O'Reilly or Autozone.

Man, for six transistors I guess you could use a second box to mount them in. Might be too much to do all on the main ecu case.

Jon k · Post by **Jon k** » Sun May 07, 2006 1:10 pm

milosch01 wrote:Pep Boys carries them. We also have a place called XL Parts that has them, but I have not seen them at O'Reilly or Autozone.

Man, for six transistors I guess you could use a second box to mount them in. Might be too much to do all on the main ecu case.

I have the idea of stacking a 2nd heatsink ontop of the stock one useing plastic spacers to rise it up.

milosch01 · Post by **milosch01** » Sun May 07, 2006 1:38 pm

That should work if you have the room. I don't, really. Suddenly today I lost my trigger signal today. RPM during start was erratic and now is nonexistant. Time for some more hardware work, unfortunately.

ptegler · Post by **ptegler** » Sun May 07, 2006 3:16 pm

I'm doing exactly the same thing. 3 wasted spark twin tower coils on a straight six. Same firing arrangement as well.
I'm using a V3 MSnS-E setup. I installed the 3 VB921's in the bottom of the coil pack. I ran the wires out the pins that were originally for the stepper motor idle lines. (pins 25?,27?,& 29?)

pics of the coil pack stuff at http://www.teglerizer.com/fi/megasquirt/ms_ignition_module.html

A shot of the engine about to get wired up this evening.... you can seethe coil pack...right rear of the engine....
http://www.teglerizer.com/triumphstuff/spit6whiteyFI/spit6_sneak_peek1.jpg

Paul Tegler
ptegler@cablespeed.com (ptegler@cablespeed.com)
www.teglerizer.com

----- Original Message -----
From: Jon k (jkensy@comcast.net)
To: megasquirt-mss@msefi.com (megasquirt-mss@msefi.com)
Sent: Sunday, May 07, 2006 12:48 PM
Subject: How to hook up wasted spark on a V6 using VB921

milosch01 wrote: I just did this on a straight-6. There is an output C, and actually more than that. I used ABC, and split the firing order using a 3-coil pack: A: 1&6, B: 5&2, C: 3&4.

Miosch01 - care to snap some pictures of your board and how you mounted a heatsink etc? Also, how did you get the output wires from the VB921s to the coil packs? Did you use a connector or something?

This post is at: http://www.msefi.com/viewtopic.php?p=118429#118429

Posted by email.

milosch01 · Post by **milosch01** » Sun May 07, 2006 4:28 pm

Cool. Good to see another straight 6 out there. I got my trigger back now but I think I finally ran out of gas :0 Wasn't more than 2-3 gallons in there last weekend since I had emptied it to replace the sending unit. My coil pack is an AC Delco flat pack, D552 or something like that. Good luck making fire (inside).

Jon k · Post by **Jon k** » Sun May 07, 2006 4:30 pm

milosch01 wrote:Cool. Good to see another straight 6 out there. I got my trigger back now but I think I finally ran out of gas :0 Wasn't more than 2-3 gallons in there last weekend since I had emptied it to replace the sending unit. My coil pack is an AC Delco flat pack, D552 or something like that. Good luck making fire (inside).

Straight 6 here too... but going to try and use coil on plug, 6 cop, wasted spark via 6 VB921s... shoudl work, right?

milosch01 · Post by **milosch01** » Mon May 08, 2006 4:24 am

With six coils, would that still be wasted spark?

Jon k · Post by **Jon k** » Sat May 13, 2006 10:17 am

milosch01 wrote:With six coils, would that still be wasted spark?

Its wasted spark because of 3 spark outputs driving 6 coils. That means 2 coils are firing at the same time, wasting one spark.

milosch01 · Post by **milosch01** » Sat May 13, 2006 11:37 am

Gotcha. I would guess the 921 can handle running both coils. But, if you can spare the other outputs I think you could drive each one seperately with recent code.

Jon k · Post by **Jon k** » Sat May 13, 2006 2:24 pm

milosch01 wrote:Gotcha. I would guess the 921 can handle running both coils. But, if you can spare the other outputs I think you could drive each one seperately with recent code.

I am doing something else. To use sequential coil firing you need a 2nd trigger... a camshaft input.... i don't want all that hassle, so I have each spark output A, B, and C going to 2 VB921s, so the VB's are each driving only one coil. The spark outputs are triggering 2.

Brad-Man · Post by **Brad-Man** » Thu May 18, 2006 2:02 pm

It is my understanding that for sequential COP, you need to have 6 VB921's, each with its' own trigger signal.

If you are only using 3 trigger signals, then even with 6 VB921's you will still be wasted spark.

Once again, this is my admittedly limited understanding.

My concern is with wasted spark, are the coils for most cars capable of handling dowble duty.

To address this, I was thinking of using some coils off of a motorcycle that are not CDI - if there are any....

I am very interested in having my knowledge improved, and will state once again - this is only the understanding I have and I'm not sure I am right...

Malachy · Post by **Malachy** » Sun May 21, 2006 10:08 am

[quote="Jon k"][quote="milosch01"]Pep Boys carries them. We also have a place called XL Parts that has them, but I have not seen them at O'Reilly or Autozone.

Man, for six transistors I guess you could use a second box to mount them in. Might be too much to do all on the main ecu case.[/quote]

I have the idea of stacking a 2nd heatsink ontop of the stock one useing plastic spacers to rise it up.[/quote]
why not just bolt it underneeth the board?so you have the board sandwiched inbetween 2 heatsinks?

Jon k · Post by **Jon k** » Sun May 21, 2006 10:09 am

Malachy wrote:
Jon k wrote:
milosch01 wrote:Pep Boys carries them. We also have a place called XL Parts that has them, but I have not seen them at O'Reilly or Autozone.

Man, for six transistors I guess you could use a second box to mount them in. Might be too much to do all on the main ecu case.
I have the idea of stacking a 2nd heatsink ontop of the stock one useing plastic spacers to rise it up.
why not just bolt it underneeth the board?so you have the board sandwiched inbetween 2 heatsinks?

Thats what I ended up doing.