Re: msd ignition
 

Had a simular problem several years ago, tried everything. Replaced the delay box and every thing was fine. Who knows what causes it. It should be rf from some where. I know run a msd noise filter on the ing box.

Re: msd ignition
 

Had a tach on my stocker did that one time.

Had a crack in my blocke shooting water on a plug do that in my Hot Rod car one time.

A friend once said you will find a 100 things wrong but only one will fix it. I wanted to smack him.LOL
Chip

Re: msd ignition
 

Either borrow or buy an MSD tester and hook it up in place of the cranktrigger. This way you can simulate a full run without starting the engine.Have the driver get in with all his gear on and make a simulated run.In my case I found out when I would turn the wheel slightly the wires for the line lock would touch momentaerly and activate the chip for the burnout. Plus this gives you the ability to rerout wires temperarly to see if it cures your problem or not.
Bill

Re: msd ignition
 

Have installed shielded wires and I think he also put a bigger vent on the fuel cell, only had a #6 vent. Going to the track tomorrow to test if it doesnt RAIN again. We have had record rain this summer, wiped out alot of races so far this year. Once again thanks for all the ideas, will keep you all posted.

Re: msd ignition
 

Steve the dragster is new, new motor and all new ignition this spring. Ran it last weekend and there is still some light popping on the top end. Tried going full rich by chahging the high speed air bleeds and that made it way worse but we didnt get any more runs after that. So we think we must be on to something, we are going to lean it out now and try that. What ign. box did you have problems with? We are running a MSD 7al3 and an HVC coil and a pro billet mag pickup distributor.

Re: msd ignition
 

Johnny, Had my MSD mounted in front of the foot box and had to make the cable back to the motor longer.
Worked fine for one season. Next season car had a miss and would not go past 5000 RPM. Checked everything from ignition to fuel system. Long story short had a bad MSD chip in my ACD air shift box. Changed the chip and car ran fine. Check your RPM chips they can go bad. Hope this helps.

Re: msd ignition
 

I've had a couple of these annoying instances over the years during which we seemed to change everything electronic under the sun. The first, as stated above, was a bad over rev RPM chip. The second was a little more odd. As it turns out a small water circulating pump we use had to be changed a week prior to a miss that developed. Apparently the windings in this particular pump were different. We eventually found it on the suggestion of putting an MSD tester on the car and turning every switch in the car on and off, 1 at a time. When we hit the water pump, the tester went nuts. I had several of these pumps on the car before without a problem. So give the tester a try, you might save some serious headaches.

Re: msd ignition
 

I had this same problem these can be very frustrating mine ended up being the High rev RPM port was bad no matter what chip I put in it would do the same thing than I ran a run without a chip and the problem went away. I send the box to MSD got it back after they said it was repaired put a chip back in and it did the excact same thing finnaly I just replaced the box and never had a problem since.

Re: msd ignition
 

I had tha same problem,the car would break down juat a few times on a run near the finish line and not on every run. I sent the 7al-2 back to MSD 2 times and each time they said it tested ok ,I removed the HIGH rpm chip from the 2 step and that solved my problem.The only problem I now have is that I still don't run the High chip.

Re: msd ignition
 

I once had a similar issue with a 7AL3 box. To make a painfully long story short, it turns out that the 7AL3 didn't like a 12 volt system. At least that was the story I got from MSD back in 2003 when I had the problem. The documentation that came with the box back then said that it would operate between 12 and 16 volts. But I had a miss above 5000-5500rpm that I couldn't figure out on the dyno. Sent the box back in exchange for a digital box and the problem was gone. Don't get me wrong, I'm a fan of MSD's products and I use them on everything. This just happens to be the one problem that I have had with one of their products. Take care.