Had our first race this weekend and the launch RPM on my wife’s car with a 7AL3 (red box) acted up in the beginning of the day.

Warmed the car up and checked the 2 step in the morning. Has a 4400 chip in it. It went to 5200 on the transbrake with the 2 step activated. I tried a different 4400 chip, went to 5200 again, both chips had the same resistance on my meter.

Tried a 4200 chip and it went to 5000, 200 rpm less. So the limiter was working but about 800 rpm off.

Decided to test the burnout RPM limiter so put a 3000 chip in it, hit the button and brought it up to 3000 and the chip worked as normal. Put the 3000 rpm chip into the launch and it went to about 3700.

Finally put s 3600 chip into the launch hoping to get around 4400 and it went to 3600. Put the original 4400 chip in it and it went to 4400. In other words it fixed itself.

Any thoughts? My only theory is that there was some type of corrosion in the chip receptacle that was increasing the resistance and plugging and unplugging multiple chips cleaned it up. The car also had inconsistent 60 times (slower than usual) this weekend. Not sure if it’s related but it ran good after the 60 and had good mph. We’re going to get a data logger on it before the next race.

quote:

My only theory is that there was some type of corrosion in the chip receptacle that was increasing the resistance and plugging and unplugging multiple chips cleaned it up.

This is very possible, and quite likely, especially if your area has high humidity, and being first outing of the season, even more so if the car is stored over the winter with exposure to the drastic temperature and humidity changes.
I worked on high-tech electronics in the field for 20 years, and one of my most effective tools was a set of various pencil erasers. Pulled out many non-functional circuit boards and modules, cleaned the contacts, reinstall and problem solved. Even just disconnecting and re-inserting connectors would frequently fix issues. High-end boards, modules, and wiring terminals are usually plated with precious metals, which helps, but most conductive metals do tarnish, and the working voltage of electronics is very small compared to A/C stuff. Usually 3-5 Volts DC, some operate on millivolts. So any bit of resistance can have an effect.
One of my pre-season car prep rituals is checking all electrical and electronic "connections", replacing wire terminals, fuses, etc. (This sometimes includes switches, and removable modules). And throughout the racing season, I often will begin the day by cycling every switch several times, and I will plug-unplug connectors to clean them up, if the car has sat for a couple weeks or more.
When you swap out a chip, I recommend you always do a double-take - (insert, remove, and re-insert them). We spend too much money at this sport to leave stuff to chance. I learned this over 15 years ago, when I was in semis, and car cranked but refused to fire as they rolled us into the water. Acted like dead ignition box. My opponent was very sportsmanlike, and chose to wait while I frantically checked things inside, then dove under the hood as the starter signaled I was on a 1 minute clock. The 10 gauge power feed to the ignition had an inline fuse holder at mid-fender, I opened it, pulled fuse, scraped the brass button ends inside it with a screwdriver, put it together and car fired. Wound up winning that round, and the final. Difference of $450 between Semi and win money. Lesson learned.
Oh, and afterward I tried to give my semi opponent some $$, he politely refused. He was not a regular, never saw him again, but that deal gave me a whole other lesson that I have tried to stick with.

Thanks for the reply. It’s been super rainy here in the northeast the last few weeks and the car has been in the trailer the whole time. We’re finally getting a data logger on the car this weekend so I’ll be able to keep a better eye on it.

Jamie

I didn't even think to tell you Sunday that I have an MSD tester as well if you need to use it to test chips. Didn't have it with me Sunday but I can bring it next race if needed.

Thanks B.J. Frank B has one at the track that I’ve used before as well.

Make sure the socket that the chip plugs into is tight on both pins. I had one loosen up and rpms where all over the place. I would cut a chip in half so you can test each side of the plug seperately.

I know a while back, before I switched to the Grid I had a red al3 that would't shift every now and then... I would make the pass, wouldn't shift so I would come back to the trailer and put in a 3000, take it on a back road in pits and let it shift at 3000 no problem. Put in the actual shift rpm chip again, and would be fine for an unknown amount of time. It did it at random, had it go almost a year and sometimes just a month or so. I never really knew what it was, but every time it did it I could put in the 3000 and it would be completely fine afterwards.