5.0 turbo wasted spark with EDIS coilpacks but no EDIS module - misfire?

[koabi]

Car info:  5.0L turbo Ford engine with EDIS coilpacks configured in wasted spark with MSD DIS4 amplifier (part 62152) but no EDIS module.  ~1250cc injectors with crank trigger only at the moment.

Background:  We were never able to get the car to strongly light the strobe in the timing light, upon cranking but we attributed that to no load in the cylinders.  Also, the ignition test mode would never cause spark.

Once we got the car to start and idle, the strobe was still dim, but idle quality was fine after Bob's recommendation to change the dwell to 3.8ms (previously was at 3.5).  After an initial tuning run, the car was ok but the car would misfire somewhat easily.  By the end of the drive, the car was misfiring rather frequently.  Due to our experiences above, I am skeptical about the spark quality.  What things should I look at?  Would adding an EDIS8 module be of benefit?  I've heard good accounts of using the EDIS8 module, so if that option is taken I still would like to VEMS to keep as much control of the ignition parameters as possible.

Also please note the VE table I ended up with below.  It seems like a huge range, but this is where I ended up for somewhat driveable air/fuel.  Didn't go past ~190kpa.

cfg: http://koabi.lazyslacker.com/VEMS/capri/v3.3_u004181-A-2011.11.17-18.03.52firstroadtune.vemscfg
screen cap of weird VE:


I'd be happy to provide any info that may be relevant.

[rob@vems.co.uk]

The EDIS-8 has the ignition drivers and the RPM decoder, both of which the VEMS has and by virtue of that - you're already using.
First off - are these coils known to be good?  It's possible if they're not new that one of the coils is breaking down as things warm-up.
Next up what are the datalogs telling you about dwell time, you may want to increase dwell time with boost to give you a stronger spark, or just increase the boost.
As you no doubt know, plugs play a role in all this - what are they like when you pull them for a visual inspection?  Also are they the right heat range for the engine? (I know more than one guy who's gone for iridium plugs a couple of grades cooler than standard because they were running higher boost, when his car wasn't detonating it was mis-firing.  The problem went away with NGK Copper plugs of the correct heat grade).

As for the fuel - are you using good values in your lambda target table?

[GintsK]

From MSD manual

The MSD Digital DIS Series Ignitions feature a capacitive discharge ignition design.

So from where we can be sure that EDIS coil will give strong spark with different kind of energy discharge???

[JohnP]

  Well the coils are new Sreaming demon coils. The plugs are ngk standard copper race plugs. They are R5671A-9  I have them gapped to .025 They worked great with my previous hvc2 coil and supported 22 pounds of boost with E85.  They did not appear to be rich or fouled. They even looked great. I am also using the same timing curves as my last A9L/PMS standalone.

  The unique thing is it was running well, After a half hours drive, they began breaking up under load at 13.8afr even out of boost. I can re check later with stock coils and see if the problem is still there..
 
  With new coils, wires, and MSD 62152 dis4 amplifier. Spark was the last concern I thought I would have..  What range dwell should I try? I am open to suggestions.

 The other concern I have is Koabi and I are currently running the car with a primary trigger only. The Vems was ordered thinking we would have a hall secondary trigger. That sensor ended up being VR to my suprise. Any chance the strange VE tables are a direct result of that..

 Is there a simple solution to remedy the hall to vr change?

  Thank you for your time. John

[JohnP]

Next up what are the datalogs telling you about dwell time, you may want to increase dwell time with boost to give you a stronger spark, or just increase the boost.

The dwell is set constant to 3.84ms  @ 13.2v. I do not have anything added to the map scale. Should I have it differently?

 Thanks. John

[GintsK]

Please understand. No OEM EDIS coil nor Screaming demon coils are not designed for capacitative discharge ignition! HVC2 seems  designed for this (if MSD7 is CD).

There is nothing to do with dwell too! Igniter just give short aprox 500V impulse to coil at the end of configured dwell time.

I think you have to find CD coils. Or if you not going to boost sky-high, use VEMS IGBTs  - it turns your system to classical inductive discharge ignition - best ignition for not ultimate race car. IMHO CD is good only for hi-boost/hi-rpm applications.

Regarding secondary Hall->VR you have to look inside your unit - does two LM1815 chips installed.

Gints

[JohnP]

 I understand what you are saying. But please explain why I could not spark the coils enough to run the car without it. The DIS4 does make a greater spark output, and it is sold as an ignition amplifier for the style coil I am running. 

 As far as the coils go, the same coils with the edis8 module have been documented to support cars making 800rwhp and high boost applications. 

 Heres an example..

This module by itself on a 392 cubic inch motor has pulled to 6500 rpm with 19 psi from a Vortech and not missed a lick. On a 32V modular motor with 25 psi it has pulled to 8200rpm with no trouble but that car also has an MSD DIS-4 ignition enhancer to increase up the spark output in such a harsh environment.

  http://www.alternativeauto.com/waterbox/wb_archives/edis.html

 Thats what I was expecting in ignition performance. 

 I appreciate everyones input here.. John

 

[GintsK]

OK.
 Bit unclear: did you already tried run the coils directly from VEMS IGBTs? Does your VEMS unit has IGBTs  (coil drivers) at all? Or you have just logical signal outputs?

[JohnP]

It has the IGBTs the vems is only a couple of weeks old and is the most recent model.

 I have read that the edis module has an ouput dwell time of 3.9-4.1ms. I am going to test the coils at 4.0ms.. I'm thinking it is very possible that the breakup of ignition is due to dwell being just below the coils sweet spot. 

 It could not even rev at 3.5ms and revs great standing still at 3.84ms so we will see what an additional .2ms may do..

[GintsK]

Does coils give strong spark if directly driven by IGBTs?
BTW IGBT presence do not depends from version but from specified options at ordering.

In principle MSD unit should be incurious for dwell. You can try whatever you want. May be it change MSD triggering. But energy for spark can be charged in capacitor in very short time - thousands time shorter than time for inductive coil charging.

[rob@vems.co.uk]

@JohnP - It may be that a few microseconds make all the difference, it all depends on where you are on the exponential charge curve:
http://www.learnabout-electronics.org/ac_theory/dc_ccts45.php
Now that you know the EDIS module kicks out 3.9 to 4.1ms you may find that 4.0 works perfectly, and that with boost you need a few more points of a millisecond to keep the spark strong.
Obviously if you're planning on holding the engine under load and high boost for prolonged periods then you might want to concern yourself with the coils overheating.

[GintsK]

Rob, they trying to run EDIS coil with capacitative discharge (CD) ignition module. Module gives around 400V spike at spark moment.

[koabi]

I can confirm that spark is being triggered by IGBTs

also, I'd like to add that the MSD amplifier has a jumper to allow for trigger bypass which will be handy if any tests are necessary

[GintsK]

Powerful spark?

[JohnP]

  It,s going to be a couple of days before any more test can be made. I discovered the alternator has a short that keeps draining the battery. I have a new one on the way, so I am forced to wait for its arrival.

 JohnP