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Discussion Starter #1
I've been struggling with new Digital 6 Plus on my El Camino for a while now. Above 5000 rpm it gives me an inconsistent miss, like a cylinder gets dropped, that wasn't and is not there when I run it without the MSD. I'm running an older pre billet HEI and I've never replaced the coil in the cap. I've called MSD 3 times to get information and i keep getting the same canned answers, I've run the magnetic pick up wiring away from everything that could cuase electrical interference. I've changed the plugs, plug wires which are now the super conducter wires MSD reccommended, changed the cap and rotor, added a sheilded magnetic pick up harness that was reccommended, and moved the box from under the hood to the passenger side kick panel where the factory computer used to be and even returned it for a new Digital 6 Plus in case the unit was causing my trouble, it still misses above 5000 rpm. I've also borrowed a 6al from a friend to try in place of the digital 6 plus to see if the problem is i my car or the box, i have yet to test it, but i will this weekend. Any chance that my older coil is going bad and can't keep up with the MSD's power output at higher RPM? It seems to run fine below 5000 but I've lost races with the miss and I can't be consistent when it misses. When i run it without the box it runs clean up to my 6000 rpm shift point. Sorry for the long read, thanks for any help or insight you can offer.
 

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VINTAGE MOTORHEAD
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Eric, I have a 6al box on my 64. I raced for decades with MSD ignitions. I am glad you are going to swap out the two boxes as a possible source. I only have a few suggestions for you.
Replace your coil with one of the MSD Blaster coils.
Ensure that your box is properly grounded.
Set your plug gap @ no less than. 050". If that sounds too big consider that many racers remove the ground tab from their plugs,as the unit will still bridge the wide gap easily.

Don't hesitate to speak to a MSD techie. No less than three times ocer the years that company stood behind their product and sent me replacement units or repairs. Pro bono! I suspect your coil is weak and the breakdown is your problem.
Also make certain you are not running lean @ WOT.
The company wants you to be happy with their systems. Watch any pro racing and you will see red MSD equipment on the vast majority of race cars.
james
 

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Discussion Starter #3
Replacing with a blaster coil is the option i'm going to go if i need to, i borrowed a good stock hei coil when borrowed the 6al just in case my coil is the problem and its an option to try for the sake of trying too. My plug gap is .055" and the box is grounded out right to the battery on a clean connection, the battery isn't that old and its an optima, so its clean. When a coil and module went bad when this car was in its stock form many years ago, it missed more under a load than spinning freely, and it seemed to miss more under a load now, so i think my problem may honestly be with the coil. I'll see what i can find and! Thanks for your help!
 

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VINTAGE MOTORHEAD
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I have the Blaster 2, and an MSD dizzy. Never had a miss. Starts instantly and runs clean and hard to the redline.l
I assume you are aware of the prohibition on welding on and near the vehicle it is mounted to and that battery charging requires disconnect of ground.
Take your concerns to the seller. Ask him for another.
Take your concerns to MSD.The people there are motorheads. They know what you want from their product. They are not clerks. They are motorheads.:dontknow:

Have you run the car with the MSD unit bypassed? You should try thst to see if you can eliminate the box as the culprit.
 

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Also check shaft side and end play.:texas:
Definitely make sure its not lean.:beer:
 

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Discussion Starter #6
I've run the MSD pro billet HEI for several years by itself and never had a miss or hiccup from it. I raced once this year with the Digital 6 and went out first round. I've been bypassing it for every race (about 7 this year so far) and hooking it all back up to try and make it work again. I'll be calling MSD back if i find the 6al works while the digital 6 doesn't.

The distributor shaft is tight with no measurable enplay. The timing is stable when i rev it up with a timing light on it. The mixture is about as dead on as i can make it without putting an O2 sensor on it, plugs aren't lean white and the procelin is clean I did richen it up and it just made a bigger pop in the exhaust when the missed cylinders mixture lit off.
 

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high speed miss

after reading this post and researching, there are 2 things going on, your right the coil is the culprit, also triple check your fuel curve as strange as it sounds i have chased a similar problem on a southern outlaw hot stock. turned out it was the 1000.00 wyllis outlaw alcohol carb was defective from the factory, although rare it does happen. worth a check in my opinion :beer:
 

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This is directly from your owner's manual:

"
INSTALLATION INSTRUCTIONS 9
MS D WWW.MS D P E R F O RMA N C E . C OM • ( 9 1 5 ) 8 5 7 - 5 2 0 0 • F A X ( 9 1 5 ) 8 5 7 - 3 3 4 4 MISSES AND INTERMITTENT PROBLEMS
Experience at the races has shown that if your engine is experiencing a miss or hesitation at higher rpm, it is usually not directly ignition. Most probable causes include faulty wiring, a coil or plug wire failure, arcing from the cap or boot plug to ground or spark ionization inside the cap. Several items to inspect are:
• Always inspect the plug wires at the cap and at the plug for a tight connection and visually inspect for cuts, abrasions or burns.
• Inspect the Primary Coil Wire connections. Because the MSD is a Capacitive Discharge ignition and it receives a direct 12 volt source from the battery, there will not be any voltage at the Coil Positive (+) terminal even with the key turned On. During cranking or while the engine is running, very high voltage will be present and no test equipment should be connected.
WARNING: Do not touch the coil terminals during cranking or while the engine is running.
• Make sure that the battery is fully charged and the connections are clean and tight. If you are not running an alternator this is an imperative check. If the battery voltage falls below 9 volts during a race, the MSD output voltage will drop and the current draw will increase.
• Is the engine running lean? Inspect the spark plugs and complete fuel system.
• Inspect all wiring connections for corrosion or damage. Remember to always use proper connections followed by soldering and seal the connections completely.
If everything checks positive, use the following procedure to test the ignition for spark. MSD also offers an Ignition Tester, PN 8998 or PN 8996. This tool allows you to check your complete ignition system while it is in the car as well as the operation of rpm limits, activated switches and shift lights."

**Have you checked both rev control limit settings to make sure you don't have one set at 5,000 rpm?
 

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Discussion Starter #9
I've turned both rev limiters up to 9900. I've read over that page many times and the part about a faulty coil is what helped sterer me towards the coil, the last part (aside from the mechanical aspects of the distributor itself) that I haven't changed. I also haven't shortened any of the wiring on the unit, they were about perfect as they sat, so its all the factory connections.

I'm thinking I'm going to swap out the coil first and then see if it misses before i swap boxes. If the miss shows signs of going away, i might entertain the thought of adding a jet to both sides to richen it up a hair just to see what it does.
 

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Discussion Starter #11
The porcelin stays clean and white, not like a lean burned white, inside the body of the plug there is a little black carbon where the body meets the porcelin to about half way up, and the electrode in the porcelin stays the black color, and the ground strap has the discolored mark halfway along the radius to the body of the plug. Honestly they look very clean. There is no evidence of detonation or white / whitish brown deposits from running lean. I pulled a plug at the track and had someone ask me how long they had been in there and were surprised when i said six months and tons of passes. The car only picks up about .02 when the sun goes down and the temps drop 15-20 derees.
 

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Discussion Starter #13
It hasn't seen more than 50 street miles this year, mostly its in the trailer to the track and the short hop to gas station around the corner. In the past the plugs really haven't looked a lot different after traffic, maybe a little more carbon on them from a slightly rich idle circuit. Its been in the garage getting the body prepped for paint when I'm not working with this ignition issue and I don't really want to get it dirty and road grimey getting ready for paint.
 

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Discussion Starter #16
750 annular discharge mechanical secondary Demon. It was after they got their quality straightened out but before they went under and quality fell off again. Its been rock solid my entire time with it.

I notched the frame and tubbed the body to put a pair of 29x11 hoosiers under it, it will cut a 1.75 60' on a decent track, mostly my local track i run 1.80-1.86 depending on the night and type of cars around. Unfortunatley no videos on youtube. Its run as fast as 12.96 @102 but Im averaging 13.0-13.2 at around 100-101 again depending on the day and humidity.
 

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Very Cool, lets get this ignition issue taken care of so you can run in the 12's every pass...:)


I don't know alot about the dig 6, but it allows you to map a timing curve with a laptop right?


So, your distributor is locked out, the rotor is phased and timing is adjusted by the box itself?

Timing is retarded at startup and added with engine rpm via the box?
 

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Discussion Starter #18
You're thinking more of the programmable 6 and 7 sereis ignition, the Digital 6 is a non programmable unit with two rev limiters, and a start retard and switchable retard for nitrous. There's several that race with them at my local track, but nobody really knows how troubleshoot them like this. My distributor is not locked out so i run 12 degrees initial and 34 total. I've never played with a car with a locked out distributor.

I'm going to get some wrench time in later, should i replace the coil before I swap in the borrowed 6al? That's the way I'm leaning, if the coil is going bad I'd rather know that before I wire in another box and spend too much time on that. At the moment, there is no wasted time, just more information gathered from these experiments.
 
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