MSD Ignition help

CraigH · 08-15-2007, 07:47 AM

I know this has been a bit of a contentious issue here, and I have searched and read what seems several hours of past posts on the MSD install and troubleshooting but cant seem to find the problem I am having. I have a 1979 SC that was having some stall issues and other problems that I think traced back to the ignition (I had a Perma-Tune box). Based on Waynes book, price and other posts, I decided to put in the MSD. I cut the appropriate wire for 6-cylinder enginers and have checked and re-checked the wiring connections many times. I put in a new MSD Blaster coil and new spark plug wires as part of the upgrade.

The car will start but just run horribly - missing, backfiring, etc. I put the old spark plug wires back on with no difference. I wired directly to the coil instead of the harness with no difference. I am starting grasp at straws. The only thing that is different in my installation is that I have as yet not hooked up anything to the tach, although logically in my head (which is often not logical at all) that shouldnt seem to make a difference. My tach is currently not operational as the needle has broken off. I figured I would wait to see if I needed the tach adapter once I got my tach fixed as most past posts seem to indicate the tach still works but the tach adapter may be needed to get a correct reading.

Any thoughts or ideas are appreciated.

kfosburg · kfosburg's Garage

Timing?

moneymanager · 08-15-2007, 07:56 AM

This may or may not help but...are you absolutely sure you have the right wires going to the right plugs? Getting two of them wrong can produce your symptoms.

moneymanager · 08-15-2007, 07:58 AM

BTW, I think you are right about the tach connection...leave that alone until you get your main problem sorted.

Steve@Rennsport · 08-15-2007, 08:16 AM

Craig:

It sure sounds like your plug wires were not installed in the correct order on the cap.

BrokeMyCar · 08-15-2007, 08:37 AM

The two wires that go to the magnetic pickup in the distributor are often swapped, creating a problem like you're describing.

Did you go with the rev-limited MSD? (6al vs. 6a)

fred cook · fred cook's Garage

(Looking at top of plug on wiring harness)

4 5 6

1 2 3

CDI Plug MSD Wires
1 System Ground------------Black coil wire
2 Tachometer Signal--------Black wire from left end of MSD unit (Tach connection)
3 Signal Ground--------------(Green wire shield) Grd. Purple wire
4 Coil Hot +12 volts---------Orange coil wire
5 Switched +12 volts---------Small red wire
6 Signal------------------------(Green wire center conductor) Pos. Green wire

Heavy red wire +12 volts (wire to starter terminal
Heavy black wire Grd. (wire to chassis and engine)

Crimp male terminals on the MSD wires and plug into the
existing wiring harness master plug.

Run a +12V power lead from the main power terminal at
the starter to get direct battery voltage to the MSD unit.

Fasten the heavy black ground wire under a bolt that holds
the CDI mounting bracket to the chassis. I also extended
a ground wire from there to the engine (stud on cam cover)
just to make certain that a proper circuit was established.

Hope this helps!

BrokeMyCar · 08-15-2007, 10:36 AM

One of Fred's earlier posts helped me with my installation (thanks Fred!), I also found the diagram 2-3 messages down on this thread useful too:

MSD Ignition Install

Babak

CraigH · 08-15-2007, 11:49 AM

Thanks for the info. I tried to be as accurate as possible with the wiring and harness connections and checked several times. I printed most of the diagrams ahead of time, including the one above. The only wire I dont have connected is the tach signal (#2). I grounded to the mounting bracket bolt and connected the main power (thick red) to the starter terminal. I will check the connections again if I get a chance to look at it later to make sure.

For the plug wires, I replaced the old wires one at a time to try and make sure they were connected correctly and even double checked with the handy cylinder and cap diagram stickers on the engine bay sill.

Basically, I have been at the same place assuming it was wiring or connections but I cant seem to find the issue, although accepting that I am a novice at this at best. Does anyone think the lack of the tach connection could play a part? The MSD literature hints at it in the troubleshooting section, but it just doesnt make sense to me.

vash · vash's Garage

i think you have the triggers (green/violet wires) swapped.

moneymanager · 08-15-2007, 12:42 PM

The tach wire has nothing to do with it...unless you have somehow connected it to the wrong wire. I ran mine for weeks before getting the tach hooked up.

rwolak@verizon. · 08-15-2007, 05:05 PM

Quote:

Originally Posted by vash

i think you have the triggers (green/violet wires) swapped.

What would be the effects of having the green & violet wires swapped? The PO of my '83 SC installed an MSD SCI-L pn 6320 unit. The car runs fine once warm. On cold start ups, the engine runs very erratic and will not idle. It seems to be starving for either gas or air. He swears the problem wasn't there with the original Bosch electronic box. I've changed the accumulator and fuel pump check valve thinking they might be the problem.

CraigH · 08-28-2007, 07:24 AM

Thanks for all the help. As it turns out, I did have the violet and green wires swapped. I switched them and the car started right up and runs perfectly (interesting that the exhaust tone is a little different - not better or worse, just different).

I dont know whether to be happy that everything works well, or angry at myself for being such an idiot, as I know I checked the wires several times and even had a friend double check as well. I made the jumper wires out of black wire for connection to the ignition harness, and I think that may have added to the confusion.

Thanks again for the help.