DragStuff

I thought I heard that when you do any welding on your car, to disconnect the ground from the MSD box of you could fry it.

Is this a true statement?

Thanks

Bruce

I pull the plugs (+ & -) on mine when welding on the car.

The reason I'm asking is, my co-worker normally runs 8.8/8.9 and he just got done doing some suspension work which included welding.

He loaded it up, took it to the track and found out the hard way that the 7AL wasn't working. The car wouldn't idle, tach was going crazy and was popping.

I thought somewhere I read you had to pull the ground off the MSD box when welding was done.

thanks

Bruce

I am like John!! I disconnect EVERYTHING that goes to the box. Rather take the time to do that then spend another 700 bucks on another digital 7


Adam

mig welding should be ok but tig i would unplug everything

Thanks,

When you talk about disconnecting everything to the box, isn't that just the ground, power wires and the harness going to the distributor?

John/ 79 Camaro, when you mentioned plugs, are you referring to spark plugs or wire plugs?

Thanks

Bruce

Power plugs - on the Digital 7 box they have connectors on them that makes it quick and easy to unhook it.

If it is a Digital box we remove it from the car.
If your tig'n take the box out. And don't put the box on top of the welder....

Everything on my car is on a floating wiring system. Even the grounds are floated back to the battery. I just unhook the ground strap at the battery and that is it. Have had no problems wih welding on the car without removing the box.

Here's an update, my co-worker got his 7AL back from MSD and nothing was wrong with it, so his next thing was to check all the wiring and make sure everything was good and had tight connections. That all checked out, he ohm'd everything, even the rpm chips and plug wires, but he still has a slight miss with new plugs.

He ran out of time and didn't get to check the coil yet, but is there a way to tell if the coil is bad or weak by using a voltmeter?

Other then the coil, the distrubutor is the only thing left.

I'm going out here on a limb but if the toggle switch for his ignition was going bad, could that do it or is a toggle switch either good or bad and not weak?

Thanks

Bruce

Toggle switch "could" be a problem, but it's unlikely. You could measure the voltage where it supplies the ignition at - wiggle the switch around some to make sure it's not intermittent or has excessive voltage drop across it. You got a coil you can borrow from someone to test?

John,

Yes he has a coil to try and I told him what your thoughts were yesterday when we talked about things.

I'm just trying to help him and rule out everything as we go and like I said, it's down to the coil and distributor.

The car ran fine before this all happened and only after the welding and suspension mods were made, then the miss appeared.

Tracks are closing soon and he wanted to get it down at least one more time and now this.

Thanks,

Bruce

John_Heard wrote:I pull the plugs (+ & -) on mine when welding on the car.

Thats the best AND only way......