MSD Digital 6AL pn 6425

MGlad · #1 (**permalink**) 06-30-2015, 05:30 AM

I just replaced my old 6AL pn 6420. When I started up the Cobra after the winter this year, it was running real rough, decreased power, but not breaking up. Wouldn't want to take it out on the road. Tapped on the MSD box a few times and then it was running just fine. I replaced the box with a new Digital 6AL and now my Lucas ammeter fluctuates between 0 and +25A when the motor revs up. It's stable at idle. I'm guessing the new box is messing with the voltage regulator. A buddy said it's a known issue, but I couldn't find anything googling the issue. Just got the box in yesterday and will call MSD later this AM. Anyone heard of this?

MGlad · #2 (**permalink**) 06-30-2015, 12:41 PM

I called MSD this AM and they just said that box draws a lot of power, you're going to have to live with it. Well, looks like I'm going to have to look for another place to find a solution.

Voyager · #3 (**permalink**) 03-23-2016, 09:47 AM

Mike,

Any solution?

A Superformance dealer just installed a new MSD 6AL ignition box in Superformance (KC 408). Installed for rev-limiter purposes.

Everything worked fine before switching boxes. After installing the new ignition box, the car runs “reasonably” well (maybe a touch rough), but the amp gage is now continually jumping, even at idle.

Not sure this is an issue…so my question to anyone is…does the continually jumping amp gage signify a problem?

Blas · #4 (**permalink**) 03-23-2016, 07:36 PM

Where did they pickup power for the MSD box?

Bernica · #5 (**permalink**) 03-23-2016, 08:29 PM

Just another example of why I finally ripped out the entire MSD system and put in a Pertronix self-contained and rev-limited distributor! A nice polished billet piece. Problems solved (knocking on wood).

Voyager · #6 (**permalink**) 03-24-2016, 06:33 AM

It was a 5 hour job. Believe the Superformance dealer ran power pickup all the way back to the battery in the trunk.

Electricity is not my friend.

Eric 1151 · #7 (**permalink**) 03-24-2016, 08:18 AM

That's why I went to the Crane HI-6 box with the LX-92 coil. 13 years and 96,000 miles on the same box and coil. Got tired of the failed MSD boxes. 2 in less than 5,000 miles. The digital 6 is even worse than the 6AL.
Eric

Nantucket427 · #8 (**permalink**) 03-24-2016, 08:26 AM

If you are a member of the Superformance Group you can pick up a technical bulletin posted to that site about MSD boxes the fix and instal

Voyager · #9 (**permalink**) 03-24-2016, 08:29 AM

Eric,

Don’t think we’ve established that the MSD 6AL has failed.

After installation, my amp gage is bouncing/fluctuating.

Is that a failure or is it a normal condition for an MSD box?

Bob

Voyager · #10 (**permalink**) 03-24-2016, 08:36 AM

Quote:

Originally Posted by Nantucket427

If you are a member of the Superformance Group you can pick up a technical bulletin posted to that site about MSD boxes the fix and instal

For the 7 years I've owned this cobra - have been a member of that group on and off a couple times. Not currently a member...

Have great confidence in the knowledge base resident on this site.

Bob

Eric 1151 · #11 (**permalink**) 03-24-2016, 08:48 AM

My amp gauge is rock steady. For the gauge to bounce that much, the amp draw is changing, probably from the MSD box. The brain trust on SCOF recommends the Crane unit. I won't even consider anything else.
Eric

Voyager · #12 (**permalink**) 03-24-2016, 09:09 AM

I hate electricity!

Could the bouncing gage be a result of loose connection?

Don’t mind buying new box (Crane), but all the other related components are MSD (not sure that matters) and I just paid $475 for installation (cause I was stumped by the tac hookup and my back doesn't play well upside down in the passenger foot well).

Wonder if the crane will plug & play into current wiring setup or will it require additional wiring?

Blas · #13 (**permalink**) 03-24-2016, 02:39 PM

Most MSD problems are related to wiring in one way or another. Improper grounding and incorrect power supply sources are the usual culprits. Coils mounted in the incorrect orientation or too close to hot exhaust headers or in high vibration areas are common issues. A power surge will kill them too. If you don't believe that, just switch off your master kill switch with the car running a few times. MSD is the system we show on the MKIII Wiring Diagrams we sell. A quick way to test the system is to disconnect the main MSD power supply from the car and temporarily power it from a remote battery. See if the bouncing amp meter goes away. Check that your wires going to the distributor from the MSD are not too close to a spark plug wire or taped together with any other wiring. Yes, the SCOF site has a fix for a jumpy amp gauge. But I would think you would be interested to know why it started jumping after the addition of the MSD box. It didn't before, and most cars have no problem. Why yours then?

Voyager · #14 (**permalink**) 03-25-2016, 05:59 AM

Quote:

Originally Posted by Blas

Most MSD problems are related to wiring in one way or another. Improper grounding and incorrect power supply sources are the usual culprits. Coils mounted in the incorrect orientation or too close to hot exhaust headers or in high vibration areas are common issues. A power surge will kill them too. If you don't believe that, just switch off your master kill switch with the car running a few times. MSD is the system we show on the MKIII Wiring Diagrams we sell. A quick way to test the system is to disconnect the main MSD power supply from the car and temporarily power it from a remote battery. See if the bouncing amp meter goes away. Check that your wires going to the distributor from the MSD are not too close to a spark plug wire or taped together with any other wiring. Yes, the SCOF site has a fix for a jumpy amp gauge. But I would think you would be interested to know why it started jumping after the addition of the MSD box. It didn't before, and most cars have no problem. Why yours then?

Will review wiring this weekend. Recall seeing the tech’s wiring work being tightly zip-tied to preexisting wiring trails.

Damn! You have a wiring diagram! You told me that years ago. Doh. Will send you a note this weekend.

STEVE-O · #15 (**permalink**) 03-25-2016, 09:16 AM

Quote:

Originally Posted by Voyager

Eric,

Don’t think we’ve established that the MSD 6AL has failed.

After installation, my amp gage is bouncing/fluctuating.

Is that a failure or is it a normal condition for an MSD box?

Bob

The ammeter bounce may be unrelated to the MSD box installation. There is a known issue with the SPF wiring that causes the ammeter bounce. It has to do with the sense wire in the voltage regulator and involves moving the sense wire to a new location to fix the issue.

There was a fix published at the SCOF site and they will have more info.
I cant recall the actual fix that was found since it was over a year ago and since I dont have my car anymore, I'm not up on the changes.

Hope this helps!

Eric 1151 · #16 (**permalink**) 03-25-2016, 09:35 AM

Since you haven't mentioned an amp gauge problem prior to the MSD Digital install, I am assuming the gauge was ok. Since the only change is the MSD install, that's where I would start looking. The problem with the amp gauge on SPF's was that the wiring was designed for an idiot light, not a gauge. Changes at the voltage regulator was the fix. Not sure what they were. Anyway, that's what Mike from Dynamic told me, over 10 years ago.
Eric

Gaz64 · #17 (**permalink**) 03-25-2016, 07:08 PM

Just rereading.
Mike says the amp gauge goes from 0 to +25.

That is charging, not discharging.

Can we get some more clarification on this?

Maybe how the MSD system was added to the car, can Mike post a circuit diagram please?

STEVE-O · #18 (**permalink**) 03-26-2016, 07:22 AM

Quote:

Originally Posted by Eric 1151

Since you haven't mentioned an amp gauge problem prior to the MSD Digital install, I am assuming the gauge was ok. Since the only change is the MSD install, that's where I would start looking. The problem with the amp gauge on SPF's was that the wiring was designed for an idiot light, not a gauge. Changes at the voltage regulator was the fix. Not sure what they were. Anyway, that's what Mike from Dynamic told me, over 10 years ago.
Eric

Well if it was a fix from 10 years ago, it must have been something else related to the ammeter.
It could be that the recent MSD install just made the ammeter issue more noticeable.
The most recent ammeter fix from a couple of years ago is this:

Bouncing Ammeter

MGlad · #19 (**permalink**) 03-28-2016, 09:28 AM

Hey guys, my Cobra is packed away, not really accessible. I was going to suggest reading the "Bouncing Ammeter" link that Steve-O posted. I won't be addressing this issue for a while, but I'll keep you posted. Has anyone read up on the SCOF tech article on this?

Blas · #20 (**permalink**) 03-28-2016, 05:02 PM

I find it interesting that you had a non-bouncing AMP meter before the addition of the MSD box and a bouncing AMP meter after the MSD installation. Some people have this problem and some don't. Doesn't make sense to me why everyone doesn't have the same problem who has an MSD installed. Got to be on how it is wired into the system. Try separating the MSD wires to and from the coil and distributor. Did they use the MSD supplied wiring to the coil and distributor or make up new wires? Are the zip tied together? Are they longer than what is supplied in the kit?

The SCOF fix works well to cure the bounce. But I like to know why it is happening.

Yes, I have Wiring Diagrams available for the Superformance MKIII (4 versions), Wiring Diagrams and Owner's Manuals for the Superformance MKII Slabside and FIA and Wiring Diagrams for the Superformance GT40 (MKI and MKII versions)
I also have Wiring Diagrams and Owners Manuals for the Shelby 7000 and 8000 cars both Anniversary and non-Anniversary editions.

Really a must-have for owner's.......