Logic spark wiring

[kjones6039]

What about on a microsquirt module? I'll be using a generic Bosch 0 227 100 211 4 channel driver, with 3 coils, for 3 cylinder wasted spark.

I just gotta ask..... How do you do wasted spark on a 3 cylinder???

Ken

[wmax351]

What about on a microsquirt module? I'll be using a generic Bosch 0 227 100 211 4 channel driver, with 3 coils, for 3 cylinder wasted spark.

I just gotta ask..... How do you do wasted spark on a 3 cylinder???

Ken

It fires each rotation of the engine, I won't be able to have a cam sensor.

[racingmini_mtl]

On a 3-cylinder (or other engines with odd number of cylinders) you still need a cam sensor for wasted spark because the code can't double the number of sparks per cycle. The only way is to "cheat" and tell the MS that you're running a 6-cylinder in wasted spark and re-order the spark outputs.

Jean

[kjones6039]

Ah ha...... The bulb comes on! Thanks Jean!

Ken

[dontz125]

Maybe it's just me, but I really don't see the difference between firing A-B every 180° and firing A-B-C every 120°… (scratching head)

[racingmini_mtl]

Firing a spark every 180° is the same whether or not you're doing sequential or wasted spark. Firing every 120° means you double the number of spark events. Moreover, firing A-B-C means you're actually firing A-C-B.

So while it is definitely doable since you can "cheat" as I described so the code could do it, it would require substantially different code which would also need to take into consideration the spark re-ordering I mentioned. And this re-ordering is specific to the number of cylinders (3,5,7,...).

Jean

[wmax351]

Firing a spark every 180° is the same whether or not you're doing sequential or wasted spark. Firing every 120° means you double the number of spark events. Moreover, firing A-B-C means you're actually firing A-C-B.

So while it is definitely doable since you can "cheat" as I described so the code could do it, it would require substantially different code which would also need to take into consideration the spark re-ordering I mentioned. And this re-ordering is specific to the number of cylinders (3,5,7,...).

Jean

The re-ordering can be done with the wiring, I suppose.

I guess I will be running my 3-cylinder as a 6. That also lets me do 2 squirts per cycle.

[racingmini_mtl]

The re-ordering can be done with the wiring, I suppose.

If you use the current code and the "cheat" then yes.

However that wouldn't be a solution for an updated code because that would mean that if someone changes their settings from semi-sequential to sequential (enable the cam sensor) then the engine would not run until the wires are switched around. Also, you wouldn't be able to sync in semi-sequential then go full sequential.

Jean

[prof315]

Just about ready, I should be testing this weekend.

We have had a couple of small setbacks with the car we will be using as a test mule but hope to have things resolved and a report on how things work in a few days.

[piledriver]

... The second step is to power the coils via the fuel pump relay. As the relay is not activated until the chip is ready, the coils are not powered until the CPU is able to control them. In the event of a processor failure, the relay deactivates and the coils are left unpowered.

I like that plan.
(In fact, I like it so much I have been doing that since installation ~3 years ago)

No power? No problem.
Easy to daisy chain relay logic.
Easier to throw a big ferrite and cap on the power feed when it's isolated.
Easy to route to a switch for inhibit when burning firmware or for security.

[mazdaspeed]

i am going to order many of the TC4427 for testing seem a great solution to me simple and easy and think a dedicated reg is also a good idea.
just some quick q,s the chip inputs are high impedance?? no need to have a current limiting resistor to the inputs from CPU? and this should work on ms1 also??

[dontz125]

The input pins are high impedance; the input current is on the order of +/-1.0 to 10 uA over the operating temperature range. No input resistor is needed. This should work just as well with the MS1.

[weeblebiker]

I was looking into this before.
http://www.msextra.com/forums/viewtopic ... 67&t=52198
I got some new info that indicates the vag coil should be controlled by a a gate driver
http://forums.vwvortex.com/showthread.p ... s-from-ECU

This is the claimed datasheet for the vw 1.8T ecu ignition driver chip designed to run the red top vag coils.
http://www.bosch-semiconductors.de/medi ... t_Info.pdf

i ended up with a couple Maxim MAX4427's in my parts bin and built up a proto board with them a few months ago, but it is cumbersome in my v2.2 box, so I just ordered some TC4422's to try and fit my jb perf 4channel board with some "creative" leg crossovering.

Jean, will you make a 4 channel board that has gate drivers instead of the igbt's soon? it looks like there is plenty of space for the 2 ic's and ancillary components. the ixdn404 gate driver datasheet page 10 has a good suggestion on cap sizes and grounding to ensure solid switching without a dedicated voltage regulator. The Maxim max4427 datasheet has good supply and grounding considerations also

[racingmini_mtl]

Jean, will you make a 4 channel board that has gate drivers instead of the igbt's soon? it looks like there is plenty of space for the 2 ic's and ancillary components. the ixdn404 gate driver datasheet page 10 has a good suggestion on cap sizes and grounding to ensure solid switching without a dedicated voltage regulator.

I may end up doing an hybrid board that can either have the 4427s or the IGBTs. That would probably be the best solution for me and wouldn't have any real drawback for users of either solution. The 2 connector pins per ignition output would not be needed with the logic level circuits but should not be an issue either.

Jean

[prof315]

Just about ready, I should be testing this weekend.

We have had a couple of small setbacks with the car we will be using as a test mule but hope to have things resolved and a report on how things work in a few days.

Success! Toyota COPs, Honda COPs, LS coils and 01 and later VAG coils all work with a 10 Ohm resistor on the output.

[davcol]

Can this chip work also (TC427CPA), it is what i have available now at the local electronic store but if not then i just have to order the correct one.

[dontz125]

Can this chip work also (TC427CPA), it is what i have available now at the local electronic store but if not then i just have to order the correct one.

Looking at the datasheet, that should work nicely.

[weeblebiker]

quick question about the current suggested 5v pnp drive circuit using 2n4033 for vag coils in the manual.

I'm concerned there is nothing holding the 5v signal input to the coil to ground when the coil is "off" with this circuit. The bosch ignition driver ic triggers an npn to ground when the coil is supposed to be "off". what about putting a 4k7 or higher pull down resistor between the 2n4033 and the vag coil?

not ideal I know, but would keep the coil input from floating.

the gate driver is the best solution, but it's not an easy circuit to stuff in the ms case until a pcb is made.

[elaw]

That's actually a very good thought. When I built mine, I think I used 10K pulldown resistors but 4.7K would work fine too.

[dontz125]

Pull down resistors tend to have fairly high values, generally 100k, to avoid voltage divider issues. I'm not sure that matters in this case.

Weeblbiker - I see you're using a V2.2; the gate driver circuit could be made using a fairly small proto board, or even just done in "dead bug" style, with the ICs glued to the lid.