Strange MSD Digital 2-step issue

Lew Silverman · 06-11-2013, 03:36 PM

How are you enabling the low-side two-step for your launch? Are you using a switch at the brake pedal or a button on the wheel? If the only time the two-step isn't working is when you're staging for a run, I would check for battery voltage on the dark-blue wire to the box. The programmable 6AL-2 has both a launch and retard function. Once properly programmed, there shouldn't be any other reason for the launch-function not to work.

Lew

buzzinhalfdozen · 06-11-2013, 08:32 PM

Ken, you said you tested the 2 step, but did you actually put in on the rev limiter or just observe the light? Also do you have or have access to an MSD ignition tester? If you do try "running" it with the tester while working the 2 step switch, which I'll assume you have on the clutch pedal or linkage? Could it be possible you're "going past" the switch on the starting line, most guys seem to give a lot of leg to the pedal after they've fully staged. As Lew stated may be a good idea to make sure you're actually getting power to the input wire. Good luck Joe

Kens429 · 06-11-2013, 09:17 PM

Joe and Lew, thanks for the response. I do have a McAmis switch mounted to the floorpan, and activated by an adjustable stop on the pedal. This stop is independent of the main pedal stop. The switch is wired in with a dash mounted light, which always works, running or not. I have not tested the blue launch wire yet, but is on the list. I repeatedly tried to simulate the failure that happens on the starting line, including your idea of pushing over center on the switch. The Gopro camera proved that the 2-step light was on, but the engine went right to the high side limiter. It is so strange that it only fails near the starting line.

Lew, I don't run the run retard yet, and haven't even plugged the computer to the box since year. It worked flawlessly until this Saturday. You may be on to something with the blue wire receiving 12 volts. I did a visual inspection, with all looking good. I did not test for 12 volts.

Thanks, Ken

06-11-2013, 03:36 PM	#1
Lew Silverman VIP Member Join Date: Mar 2010 Location: Newport News, VA Posts: 1,435 Likes: 371 Liked 129 Times in 59 Posts	Re: Strange MSD Digital 2-step issue How are you enabling the low-side two-step for your launch? Are you using a switch at the brake pedal or a button on the wheel? If the only time the two-step isn't working is when you're staging for a run, I would check for battery voltage on the dark-blue wire to the box. The programmable 6AL-2 has both a launch and retard function. Once properly programmed, there shouldn't be any other reason for the launch-function not to work. Lew __________________ Lew Silverman #2070 "The Wagon Master" N/SA

06-11-2013, 08:32 PM	#2
buzzinhalfdozen Senior Member Join Date: Sep 2006 Location: Bellevue Ohio Posts: 984 Likes: 0 Liked 11 Times in 8 Posts	Re: Strange MSD Digital 2-step issue Ken, you said you tested the 2 step, but did you actually put in on the rev limiter or just observe the light? Also do you have or have access to an MSD ignition tester? If you do try "running" it with the tester while working the 2 step switch, which I'll assume you have on the clutch pedal or linkage? Could it be possible you're "going past" the switch on the starting line, most guys seem to give a lot of leg to the pedal after they've fully staged. As Lew stated may be a good idea to make sure you're actually getting power to the input wire. Good luck Joe __________________ Joe Buchanan SS/BX 3117 Last edited by buzzinhalfdozen; 06-11-2013 at 08:35 PM.

06-11-2013, 09:17 PM	#3
Kens429 Junior Member Join Date: May 2007 Location: Bright, Indiana Posts: 5 Likes: 0 Liked 0 Times in 0 Posts	Re: Strange MSD Digital 2-step issue Joe and Lew, thanks for the response. I do have a McAmis switch mounted to the floorpan, and activated by an adjustable stop on the pedal. This stop is independent of the main pedal stop. The switch is wired in with a dash mounted light, which always works, running or not. I have not tested the blue launch wire yet, but is on the list. I repeatedly tried to simulate the failure that happens on the starting line, including your idea of pushing over center on the switch. The Gopro camera proved that the 2-step light was on, but the engine went right to the high side limiter. It is so strange that it only fails near the starting line. Lew, I don't run the run retard yet, and haven't even plugged the computer to the box since year. It worked flawlessly until this Saturday. You may be on to something with the blue wire receiving 12 volts. I did a visual inspection, with all looking good. I did not test for 12 volts. Thanks, Ken