Strange MSD Digital 2-step issue

[Kens429]

I race an old stock eliminator car in the UMTR. I have been running a MSD Digilal 6 programable ignition for the past 2 years with no issues until last night. The 2-step is not working only at the starting line. I checked it in the pits,; no problems. I checked it in the staging lanes; no problem. I checked it in the water box; still good. Then as I stage; no 2-step. After the pass, I test back at the trailer without shutting the car off, it freakin works fine! I have a light on the dash that indicates that the switch is activated, it was lit every time. The line lock is wired separate, and is released by hand. All tests were preformed with and without the line lock to rule it out. I can see no wiring problems. I made 5 passes, with the same result. Could the track timing equipment be causing some sort of interference?

BTW first time racing at the very nice Lyons Raceway.

Ken

[buzzinhalfdozen]

Tracks equipment...NO. I've had this issue before, where in relation to your ignition box is the 2 step module? And where do you have it grounded? Also you say you tested it...you actually ran engine up to the limiter or observed the light coming on? I've had 1 RPM switch and 1 2 step that when place on the ignition box (MSD 7al2's) would not work, as soon as I moved them and grounded them at a separate point they worked fine. One other thing I've seen on my sons car pins spread out on the 2step his would work at times but not every time, simple fix for his used small pick tool to tighten female terminals. Joe

[Kens429]

Joe, thanks for the reply. I don't have separate modules with this system. It is the digital programmable box(model 6530). I have to use a laptop to change the 2-step. I checked most of the grounds at the track Saturday, and will be checking the rest this week.

Thanks, Ken

[buzzinhalfdozen]

Ok sorry completely read over the digital part.

[Lew Silverman]

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]

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]

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