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MSD 6a install problems

6K views 62 replies 12 participants last post by  AlexThePhotoGuy 
#1 ·
Hey y'all. It's been a while since I've posted on here. Having two young kids has put a big slowdown on much of my Jeep work. But the youngest is almost ready to ride in it so I wanted to get my CJ7 tuned up for fall!


Background:. I have a 1985 CJ7 with the i6 engine. It has the Team Rush upgrade, new plugs, wires, Nutter bypass, and a new Motorcraft carb on it. The carb was the latest addition and that install went fairly flawlessly, including changing the timing to 8 Degrees BTDC (vaccum advance plugged for that timing change, then plugged back to the bottom of the carb once everything set up).


The carb upgrade made a big difference in power, but my mpgs were still terrible (10mpg or so? Same as before) and the exhaust sometimes smelled like unspent fuel. I figured my next best step would be to get the MSD 6a to help with spark detonation.


I installed everything as described in the MSD diagram (attached). I also put in a new MSD Blaster coil to replace the stock one.


-Big black to negative on battery
-Big red to positive on battery
-small orange (+) and black (-) to the coil.
-magnetic pickup to distributor
-small red to the red coming out of the original coil connector. That one was the only thing I cut and spliced- the stock coil (horseshoe shape) connector had a red wire coming back out of the red side, so I cut that wire and crimped on a connection that would mate with the small red coming from the MSD.


These were all the notes and instructions I found in the MSD manual and Jeep Forums. The only thing I found the differed was that I cut one of the loops on the 6A. I didn't see this in any of the Jeep forum notes but in the MSD install notes it said to cut one of the loops if you have a six-cylinder engine. It comes from the factory ready for 8-cylinder. Can anyone confirm this is correct on an inline6 CJ7?


Once everything was installed and took a few minutes to get it to fire up. It eventually started but ran pretty rough. I didn't feel comfortable even revving it because it sounded like it was way off. I'm just a hobby Jeep mechanic so I couldn't tell you if it was backfiring, timing was off, or something else. when I would stick my head in the engine bay it sounded okay at idle but sounded terrible at the tailpipe. And then whenever I would rev the engine it sounded terrible.


Seeing as I think I connected everything correctly and it was running fine before installing the new coil and MSD, I have no idea where to start. All of the connections are very solid, though I haven't soldered or weather sealed them yet because I wanted to make sure it would run first.


Any thoughts would be appreciated! Please see attached photos for each connection.
 

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#5 ·
I was thinking about that red wire.

Isn't that a resistance wire that depending upon the load the MSD gives it could drop the voltage down making it erratic.?

There are two red wires on there, One to the Starter solenoid and one (the resistance wire) to the ignition switch, (through the tach if equipt)



I think that MSD terminal was suppose to be plugged in the the horseshoe connector without any cutting. You can plug it into the side that slips over the coil.
I'm worries just what you cut there.

You can see if it makes any difference if you connected it directly to the (+) on the battery. IF that helps then you can connect it to the red lead in the 2 pin connection for the ICM.
 
#7 ·
Being the resistance wire 'shouldn't' cause an issue as that is just a turn on/off signal for the msd box and should turn the box on with it's approx 9 volts. Thinking about it more, I think the OP is running into the same issue with when you switch to an HEI and have a run on issue, being that a diode is needed to be added to the alternator sense wire to stop the backflow of electricity keeping the Jeep running. Page 8 of the instructions deals with run on and a gm style alternator. OP, have you reset the timing since converting over to the msd box? Also what wires are you running? The MSD specifically states that solid core wires will not work. Did you also adjust the plug gap per msd's instructions?

https://documents.holley.com/6201.pdf
 
#8 ·
I have the same MSD 6AL unit on my CJ and don't recall ever having to cut a wire for the 6 cylinder engine, but could be wrong, it was a long time ago.

Here's a wiring diagram I used pictured below. I use a E-coil instead of a canister coil but it makes no difference.

You may need to add a diode to the eliminate the "run on" condition you are experiencing too.
 

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#9 ·
OP, I have to ask, did you cut the correct loop on the MSD unit? IIRC, it's the red loop that gets cut for a 6 cylinder engine.

Beyond that, It sounds like you did everything correctly. I have heard of some MSD 6a units not working straight from the box. You may have to send your unit back to them for testing.

Matt
 
#10 ·
Loop color doesn't matter. It says pick one in the instructions.


OP my suggestion would be to make sure your firing order/plugs are correct on your wires. Second suggestion is to route try and mess with the routing of the wiring that goes from your coil to the box, and ensure the other wiring to and from the box is not near the coil wires or plug wires. There is a ton of electrical noise and EMF in those areas; I've seen problems when all the wires are next to each other and getting erratic running.
 
#11 ·
have you checked manifold vacuum and tuned the carb correctly? Gas smell, poor mileage and engine dieseling... Could be running too rich and compression is keeping it going until a load is applied.


The MSD systems do have a possibility to feedback and cause themselves to run-on so in some set ups you need to install a capacitor in the ignition wire (i think). It is well documented on all the MSD/teamrush posts so check those. I think it is even in the MSD install documents about where to install it. There was one in my kit when I bought it. I put this on my AMC 360 and the thing practically starts itself now. It is a beautiful sound and I am thinking of installing a big shiny red push start button.



-MAP
 
#12 ·
Thanks y'all for the quick responses. I'll test the small red wire volts as well as try to run it from the battery. The wire I connected it into was simply a red wire that comes back out of the horseshoe connector. It has just been dangling there unconnected to anything since I owned it. All I did was cut the tip off and used a crimp connection. I'll keep you posted.

As far as plug wires and spark gaps, I have them both from the recommendations on the Definitive Team Rush thread on Jeep Forum - plug wires are Motorcraft WR4050... But I can't find anywhere from the descriptions online whether those are solid core? And the plug gap was 0.045, but I may as well double check those.

I'll also tie back the old loose wires to be safe.
 
#18 ·
The hoseshoe is just hanging out for the ride, it is not connected to anything. Keith's diagram only shows using the horseshoe if you retained the factory coil. The op is using a new msd blaster 2 coil with ring terminals on the orange and black wires.
 
#17 ·
The jeep would not start if the was hooked to the - side of horseshoe. The green wire is no longer hooked to anything at the other end as it was hooked into the duraspark ignition module. All the red wire that is hooked to the red wire in the horseshoe is doing is telling the msd box to turn on.
 
#20 ·
Can anyone tell me if these are solid core spark plug wires? I can't tell.

https://www.oreillyauto.com/detail/...orcraft-ignition-plug-wire-set/wr4050/4493539

WR4050 is the p/n for the set and the wires themselves say E5595.

And here is a photo of the horseshoe setup at the moment. Going into the horseshoe connector is a red wire with a white stripe on one side and a green wire on the other side. Then coming out of the red side is another red wire. This is the wire that was not connected to anything before and I put a crimp connector on the end to connect to the MSD.
 

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#23 ·
Can anyone tell me if these are solid core spark plug wires? I can't tell.

https://www.oreillyauto.com/detail/...orcraft-ignition-plug-wire-set/wr4050/4493539

WR4050 is the p/n for the set and the wires themselves say E5595.
.
Don't think so. They are Noise Suppression type and typically those type are not solid core.

Specifications:

Boot Type:180 degrees
Color:GrayCore
Material:SiliconeLength:11,11, 13, 15, 15, 17 Coil 14,12 in
Material:SiliconeNoise
Suppression Type:Yes
Wire Quantity:8Wire
Size:8.0 mm
 
#22 ·
Alex,

The red wire you connected to was originally connected to a radio interference condenser. As mentioned, it should be adequate for switching the MSD box on, but I'm still not a fan of using that power source. Those horseshoe connectors are notorious for failing, and you are getting something less than 12V to the box because that circuit has a resistor in it. I've installed the MSD ignition on both my 258 and 360. Both times I spliced into the factory ignition wiring upstream of that resister, and both installs went flawlessly. That may not be your problem, but it may be contributing to it.

Did you determine if your plug wires are solid core, or not?

Matt
 
#32 ·
Alex,

The red wire you connected to was originally connected to a radio interference condenser. As mentioned, it should be adequate for switching the MSD box on, but I'm still not a fan of using that power source. Those horseshoe connectors are notorious for failing, and you are getting something less than 12V to the box because that circuit has a resistor in it. I've installed the MSD ignition on both my 258 and 360. Both times I spliced into the factory ignition wiring upstream of that resister, and both installs went flawlessly. That may not be your problem, but it may be contributing to it.

Did you determine if your plug wires are solid core, or not?

Matt
Alex,
I would ditch that horseshoe clip to the coil. The CDI boxes that I use have 525 volt going to the coil. MSD claims more than that. https://www.holley.com/products/ignition/ignition_boxes/street/parts/6425
I run those wires from the CDI box directly to the coil, (no splices) and power source directly to the battery, then you on/off keyed/switched power source, then your triggering wire either from the points, or the stater/ignition pick-up in the distributor.

Plugs are as personal as what engine oil you think is best.
Autolite 985,
(I like these) Champion RFN14LY (82),
NGK ZFR5N (3459)

UTN
 
#24 ·
I ran a test yesterday connecting the small red wire directly to the battery as well as trying to move the other wires around to decrease interference... No luck, same problems. I'm thinking it's either the MSD box itself, or somehow my timing is a problem. I also had my head in the engine area and pulled the throttle and when it revved up there was a knocking/ clicking sound from the engine.

Here are a couple other photos. Any other thoughts? Could the ziptie bunch of wires next to the battery a problem? Those are all the new MSD wires.






engine.
 

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#26 ·
Nothing back from Holley yet. I have until Thursday to return it under a normal return policy.

I disconnected it and reconnected stock ignition (plus the new MSD coil). It fired up as usual and ran pretty well. I adjusted the idle screws (one side was running fairly rich) and the float (it was slightly low, but not bad). I also re-confirmed timing is 8 degrees BTDC. Don't think I have any vacuum leaks- as of the moment I only have the PCV and dist advance connected to the carb (no fuel vent or EGR).

I'm going to double check my plug gaps... But other than that I'm at a loss. My battery grounds to the block and I have a strap connecting it to the frame. I confirmed that it still runs poorly with the MSD even when I connected the small red wire directly to the battery.

Any other ideas?
 
#27 ·
My vote is for sending the MSD box back.
 
#29 ·
Quick update. I returned the box and got a new 6AL. I haven't hooked it up yet, but plan to this week.

I pulled the plugs to check the gap and they all were around 0.45" (though it ran rougher after I did this so I may have overgapped them).

Here is what they all fairly consistently look like. I knew it was running rich but this I believe confirms it. I adjusted the float and idle screws (one of the idle screws was about 1.5 turns out further than the other).

What do I check next? Jet size? I bought the 2150 off the eBay guy and initially was quite happy until I discovered I'm still getting 9mpg and it all smells fuelly.

Wood Fastener Engineering Gas Household hardware
 
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