Troubleshooting a MSD digital 6 plus

[Jee Ent.]

I'm currently running a engine in the dyno. 2165ccm, IDA, 11,5 CR, Extremely welded and ported heads. No power under 5000rpm.

The ignition system has 20 passes on it. So it's like new.  MSD distributor, HVP coil, msd wires and Digital 6 plus box.

The problem is... It misses at higher rpm under load. And the problem is the digital 6 plus box.

Have tried:
another Distributor... no change
another coil.. no change
other Wires... no change
Relocated all wiring... no change

Changed the box with an older beat up MSD 6 AL. And all the problems are gone. And all the different parts works great with the 6Al.

I've googled the problem but no solutions. Only the same problem...  Has anyone of you had problems with the Digital 6 plus??

Another problem with it is that it has killed two tach's. First one was a Autogauge cheapchit. (the owner blamed the Autogauge.. and didn't think more of it). The second one a Autometer unit. That worked two passes before it went dark.

No need to answer that you have no problem with yours... It's not the first Digital 6 plus I'm dynoing. And there has never been a problem earlier. So I know they can work..

[Ragtop]

Where is it located in the car? A friend of mine had problems with his, it changed the ignition by 10 degrees all of a sudden he moved it outside the car and it worked fine. Something might interfere with it.

[WhiteTrash]

I've had the same problem with the digital 6 in my car.
The box was fitted on the inside of the fire wall and on the rear boot floor.
Always had a misfire above 6500rpm and sudden breakdowns cruising.
Tried different dizzies, coils, wires etc and have taken it out last year after I found out others had the same problems.
Seams they are not the most reliable units and very fragile. At least in a VW Beetle.
Not sure if people with 6 or 8 cylinder cars have the same issue.
As Johan said, maybe try and fit it in the front. Perhaps the dynamo or regulator are interfering. I never tried it.

Frank

[Jee Ent.]

The engine was in my dyno room, not in a car. The digital 6 plus unit was standing on rubber feet, on concrete floor. No alternator was used. Just a normal 220v to 12v  battery charger. Connected to the optima redtop battery that provides 12 volt to the engine electrics. The logger says steady 12,9volt through the whole pull. The coil was hanging in free air 30cm above the engine. All plugwires separated and not near any metal other than the intakes. All other wires separated from metal, eachother and plugwires. The wires, not in use, like the 2 step activation wire. Was separated and insulated.

We spent about 5 hours of troubleshooting. After chancing to the old 6AL unit (that should be more picky about voltage according to the factory specs) all jetting and timing was done in 1 hour 

The engine was also easier to start with the 6AL. Tried both cylinder settings 0 and 4 on the digital 6 plus without any difference. 

I don't have a solution to the problem. And from what I can find online... they will work fine if you test the box with a simulator.

My guess is that is has some gremlins or bad soldering in the retard system. I can't see any spikes or dips in the lambda reading when the missing fire occurs. So I believe it fires... but with a lot of retard.

[Steve D.]

You can look for blame on the install of the digital 6 (you know MSD will if you contact them), or you can just switch to an ignition that just works.  I have seen more people have misfire issues with the digital 6 than I've seen issues with all the other MSD boxes combined.  Even working with MSD will just get your box sent back, analyzed, and returned for a fee with no change in the outcome.  Best case scenario it comes back working with no explanation of anything being wrong, and you wait for it to act up again.

MSD makes some fantastic ignition products- this is not one of them.

[modnrod]

Well then, there you go.

MSD is obviously the "DYNA" of the car world! 

[Jim Ratto]

I recently changed my CD box over from MSD 6A to Crane HI6R

it was a worthwhile change, just from aspect of ease of tuning car now.

[Paul Bahnstormerz]

I've got this ignition going into the car I'm currently building.
After chatting to various people about the ignition setup I'm putting together the consensus was install the MSD Noise Capacitor

http://www.msdignition.com/Products/Accessories/Installation_Acc_/8830_-_Noise_Capacitor,_26_Kufd.aspx

Some additional bits here

http://www.erareplicas.com/427man/wiring/msd-install.htm

[fish]

Run a magneto

[Dave Harryman]

that's why I run a mag