Fast Talk with Jeff Smith: Digital Devices

leadI’ve been doing some research on electronics and issues with electronic interference called radio frequency interference (RFI) and electro-magnetic interference (EMI). I won’t get into all the details but there is an invisible battle going on underneath your hood that most of us probably aren’t aware is happening.

Along the way, I’ve been looking into forums and discussion boards and I see a lot of car guys really frustrated with digital control boxes from many different manufacturers. The frustration level is usually extremely high and I understand that because it’s happened to me on many occasions. I’ve also learned something that is rarely if ever talked about- so here we go.

Essentially it’s the relationship between the user and what is often referred to as “the little black box.” The little black box can be a digital EFI controller, it can be an electronic trans controller, or even a simple data logger. The common denominator is the term digital. When I first started working on cars, I evolved through points ignition and I can remember when the first aftermarket electronic ignition came out when my buddies were racing their ’57 Chevy. It was an Accel unit called the Breakerless Electronic Ignition or BEI. That was around 1974 or so. It was cool – and we didn’t have a clue how it worked!

More to the point, whenever we had a problem that was even remotely associated with timing – we blamed the BEI. Flash forward now to the late ‘80s and I’ve installed a new DFI fuel injection system on my Chevelle. We’d run it on the dyno and everything was great. But when we bolted it in the car, it would start and idle but would die the moment you hit the throttle pedal. The short version was a dead MAP sensor – but it took me a week to figure it out.

Roughly a month or so later the engine suddenly lost spark and died. I instantly blamed the computer. DFI’s then-owner John Meaney went over it with me several times over the phone. He was patient with me for awhile and then finally said – “It’s not the computer – figure it out!” He was right. It turned out the wire to the tach had grounded out under the dash when we didn’t properly route it during an all-day thrash. It became pinched between the steering column and the bracket and it took awhile before it finally disabled the ignition.

Another classic illustration occurred after I had installed the EFI system on my Chevelle. The engine was very inconsistent in returning to a base idle setting. I played around with the electronic tuning side for a day or so and got nowhere. I finally asked a friend who is very good at tuning to look at the car. The first thing he did when the idle didn’t return was to open the hood and touch the throttle linkage. The nice billet throttle body was mechanically hanging up slightly and that was the problem. It had nothing to do with electronics, yet I was again blaming those invisible little electrons for not doing their job. Needless to say, I looked like an idiot.

Can you see a theme beginning to form here? I could probably come up with at least ten more examples of where my inattention to detail caused the problem that I instantly wanted to blame on the little black box.

This can easily be traced to us not trusting the parts that we don’t understand. I’m sure that ancient man was probably completely spooked by the first total eclipse of the sun and wondering what he did wrong when now we know the moon just got in the way. But if you don’t know much about the astrophysics and how the earth, moon, and the sun are arrayed, you might be blaming that eclipse on something else.

The internet forum posts that I mentioned earlier also often claim that the box they sent back was really defective – and some probably were. But then again, maybe not. I recently installed a new 4L65E trans and when it almost immediately started to act up, everybody I spoke to immediately blamed TCI’s control box. But we had tested the trans on my trans builder’s (RaceTrans.com) test stand and it ran great. I suspected an issue related to the installation in my ’64 El Camino. The short version is that my plug wires were more than a bit noisy – generating a nasty electronic cocktail of both RFI and EMI. All that electronic noise invaded the throttle position sensor (TPS) wires and the result was electronic transmission controller chaos.

All we had to do to fix it was separate the plug wires from the TPS sensor wires and the trans now works like a champ and everybody is happy – especially me. But it made me wonder about how many ECU boxes have been returned to companies like MSD, TCI, FAST, Holley, FiTech and all the others where that insidious mixture of RFI and EMI were really to blame. Think of RFI and EMI as placing the moon between you and the sun. If you don’t know what’s really happening – who you gonna blame? My guess is most of the time, it’s not the little black box.

So the point of all this is that it’s human nature to blame the component that you don’t understand or trust the least. While it’s always possible that the box might be at fault, it’s more likely that something else is going wrong. My latest adventure now has me trying to figure out how LS engine crank sensors work. I’m having an issue with a rev limiter that is not working properly. I’m pretty sure it’s probably something I have done. I just have to run it down.

About Jeff Smith

A clue into how long Jeff Smith has been writing technical automotive stories might be his following of second generation readers. Writing continuously for nearly 40 years, his focus with Xceleration covers all things technical. His collection of cars includes a bevy of Chevelles and El Caminos. When not writing about cars, he likes to spend time with his wife Valerye, children Amber and Graham, and granddaughter Celeste.