To start off, my truck is a '72 Suburban with a 6.0L, Holley 650 double pumper, and a 4L60E run via a FAST EZ TCU box. I got the truck up and running months ago. After putting about 1500 miles on it, it suddenly started running like crap, wouldn't idle, and had no power at all. I verified that only one side of the motor was firing so I limped it over to Outlaws Rod & Custom here in Norfolk, and we got MSD on the phone, and they helped us go through pin by pin, and verify that the harness was good, and that all of the grounds were good. The Box is currently grounded to the passenger side cylinder head, with braided grounding straps connecting the motor to the frame in two places, and a cable connecting the battery to the motor. They then instructed me to send the box in, as everything was point towards a bad box. They currently have that box and are looking into it. In the mean time, as this is my daily driver, I went ahead and ordered a second box. I installed it, had the truck dyno tuned, and its been running great for the past few weeks or so....even made 300 hp and 330 lb/ft to the wheels. Today, as I was coming home from work, everything went to hell again....exactly the same symptoms....truck slowly dies at a red light, fire it back up, have to keep my foot in it to keep it idling, and is making NO power. I haven't had a chance to go verify pins and grounds again, but Im quite certain its the box....AGAIN! The tech at MSD indicated the first time around that they were having real problems with their quality control on the circuit cards in these boxes as of late. Im going to call them again tomorrow, but in the mean time, does anyone have any bright ideas? Or better yet, are there any other options besides the MSD box for running the ignition on a carb'd LS?? Im pretty frustrated at this point, and would greatly appreciate any help. Thanks!

 

Only thing I got is that the box is supposed to be ground directly to the battery. Am not saying that your ground set up is poor, just that their instructions say to ground directly to the battery.

 

yea, I just went through the directions for the 18th time and caught that.....may see if that changes anything, although the fact that the first box went bad, we replaced it without changing anything else, and then it ran fine for another 1500 miles still seems to point to bad boxes but we'll see what MSD says tomorrow

 

I used a Microsquirt to run just the ignition on the last carbed LS I worked on.
Works great.

 

My box is only 8 months old . I bought a complete intake box and carb kit.
I chased a stupid intermitant miss for over a month .
Turned out too be one of the female terminals on the main coil plug was stretched open enough too let the male terminal rattle around.
Only took a poke with a small screw driver too bend it tight again.
It was the msd loom and exact symptems your describing.

 

Interesting...how did you determine by looking at the plug that the female side was too big? I could see finding a bent male pin, but I would think it would be difficult to diagnose the other side.

 

When the engine was idling if you tapped the plug and the motor would stumble . I could see that 1 of the 9 ? holes was clearly bigger .
i stripped the male terminals out of the plug and went over each hole too check and one was sloppy aas hell.
it controled all 4 coils too , if. It was only affecting one it might not have been noticed.
ya gotta check the dumb stuff first aye.!!

 

I tired to mess with it this afternoon but the car won't even idle....it will turn over and start, but unless I keep a boot full of throttle in it, she just dies. It sounds like its the driver's side bank thats dead. I borrowed a friend's MSD box so Im going to start by just swapping the box out and see if that does anything. Im also going to run the ground straight to the battery, although it is still very secure to the back of the head. We'll see what happens.

 

I had this problem. Originally I also thought it was a ground issue as I originally grounded to the same location on the frame as the engine. It would run great, then without warning it would drop the drivers side bank of coils. The quick fix would be to disconnect and reconnect the plug to the coil harness.

After speaking with an MSD tech guy he instructed me to do the ground straight to the battery. I did and for a while it seemed to work, but ultimately it still did it. Turns out the problem was the connection between the msd harness and coil harness. I think the vibrations caused the problem, and found that if I disconnected the plug from the clip holding it to the bracket ( just dangling there held only by the wires rhemselves), it stopped. I was able to put 3k+ miles on the car without issue by doing that, instead of dropping the drivers side bank on a fairly regular basis (4 times in a couple hours one day).

I tried packing the connector with dielectric grease with no improvement. A couple weeks ago I got a new coil harness and installed it, but haven't had much time to put many miles on the car yet.

 

Thanks! That's helpful and interesting...my coils are actually relocated off the valve covers, so I also have an extension harness in the mix between the MSD harness and the coil harness...guess I'll have to start by looking at that. I have considered cutting off the factory style connectors and using aircraft style "cannon plugs"

 

Has MSD gotten back to you with results from the returned box?

 

I had similar problems driver side bank would just start missing. I have the motor on a airboat so I could just turn around and mess with the plug and it would start running good again. Like someone said above I put dielectric grease with no luck. so i ordered two deutsch connectors from jegs and made my own harness connections motor runs perfect now.

 

You have too wonder how often a bad plug is too blame and not the box. Im lucky mine was obvious when i wriggled the plug as the engine
idled

 

yea....MSD still hasn't gotten back to me about the original box, but Im giving serious consideration to pulling it all apart this weekend and hard wiring the MSD harness all the way to the coil in order to take the plugs out of the equation. I build this rig as a reliable daily driver and with these electrical gremlins, its anything but......

 

I too had a problem with the Msd 6010,It would shut of the drivers side bank for some reason.It was only firing the passenger side.So I disconnected the coil plug harness like mentioned above and that seemed to clear it up for a bit,but would start to act up again.I changed the the front#1 coil pack also when it would start misfiring or should I say not firing that bank and that seemed to fix that issuse.Not sure if it was a coil pack or not,but what I also found out that if the Battery is not properly charged it would act up.The alt wasn't charging it,had wrong resistor on it to turn on the alt,so alt was not working and apparently the Msd6010 was running of the batt way below 12.50V it was more like 12.00v or less if I recall correctly.To sum it up its been working.Although still don't drive this ls carb swap that much fixing other stuff on it..

 

Got the original box back from MSD today with a work order saying that it tested properly on their bench at the factory.

That, along with the fact that both times Ive had this problem, its been the driver's side bank leads me to believe I have a wiring problem...most likely the connector. What I may do this weekend is cut the connector off the MSD side of the harness and off the coil side of the harness and hard wire them together to eliminate the connector entirely. In addition to running the ground directly to the battery, that will hopefully remove all variables from the equation.

I did go out and verify that my battery is at 13.5 volts at all times. My TCU trans controller is powered directly off the battery and through the digital programmer, you can read exact battery voltage, so at least I know Im good there.

 

Thanks for the update. It's helpful to all of us as you document your way through this. I'm so concerned about our MSD 6010 that we remove it & bring it inside during Winter.

 

Haha....thats funny and unfortunate at the same time....you'd think with the number of these out there, they'd do something about the issues. As a side note, do you know what the date code is on the back of yours? The one I just got back is SEP of 13. Im going to check the one in the car this weekend. Im just curious if there is a bad year, or a bad batch out there.

 

June 14. We swapped from EFI to carb this past Summer. Had an older one in a mid 2011 build, but, sold the car Winter 2013. So, don't know the exact mfg. date of that one. Did not have issues w/ that box. Hope to not have problems w/ the 2014 box; knock on wood.

Maybe everyone could post their MSD box mfg. dates?

 

Mfg date DEC 13