Electromotive ignition problem

I had the 308 out today for an FCA rally and luncheon. Had a great time, drove the car around 150 miles, and it ran perfectly. Absolutely great day, until I was about 2 to 3 miles from home. I turned a corner, hit a bump in the road, and it was like the ignition switched off. Pulled to the side of the road and tried to diagnose it. Fuel pump was working. No fuses were blown. Timing wheel and crank sensor were in place. No evidence of damage to any of the wiring. Engine cranked with the starter, but refused to start.

So I had the car flatbedded home. I checked the Electromotive unit with the help of a friend. The first time we tried it, the status light turned green when I put the ignition on, and then when I cranked it over, the status light blinked red once, and then nothing. Turned off the ignition, waited a moment, turned ignition on, status light went green. Then cranked it over and it flashed red twice, and then nothing. Turned ignition off, waited a moment, turned ignition on, and nothing at all happened with the status light, it stayed dark. Turned it on and off several more times, still nothing at all. And the car won't start, no spark.

So, any ideas what could be wrong??

 

It's the XDi unit, I got it from Nick's Forza two years ago. Yes, one of the first things I checked was the timing wheel and crank sensor. They appeared to be fine, neither had shifted, moved, touched, etc. Both locked in place, as they should be.

 

Thanks Michael. I spoke with tech support at Electromotive a short time ago. They basically told me to do the same testing that you described, and if the status light is not coming on and functioning properly after verifying power supply and ground and all other connections, to send the unit back to them for testing.

It's just very strange that this would have happened at this point. I could understand if it happened at the time of installation. But the car has run perfectly for over a year, including all day yesterday, and then POOF, 2 miles from home, she dies. Makes no sense.

I'll let you know what my testing shows.

Steve

 

The XDi unit, the relays, the fuses and the tach unit are all mounted in the rear trunk area. So they are not exposed to the weather, engine heat or any other adverse environmental issues. The wiring harness passes through a hole in the wall between the rear trunk space and the engine compartment, but is wrapped in plastic flex tubing to protect it. I'm going to check the power source and ground connections, and the crank sensor with my multi-meter before sending the unit back, just in case it's a wiring problem, not the XDi.

 

Okay, I checked the voltage on the leads and found something unusual. So let's see what you guys think.

With the ignition off, I measured 12.3 to 12.4 volts across the battery terminals. I also measured 12.3 at the two fuses in the hot leads to the coils that is connected to the terminal on the starter. I disconnected the XDi plug with the wiring harness and measured pin 6, the power lead that runs from the ignition switch, to ground and got 0, as it should be with the switch off.

Now, I turned the ignition switch on to the run position. I got 12.3 across the battery terminals. Pin 6 to ground showed 9.1 volts (that would explain why the XDi was not working, it needs at least 10.5 volts to operate). Now here's the really odd part -- I measured the hot lead to the coils from the starter, and it measured 9.3 volts also.

So what's going on? Could I have a short somewhere? But if so, wouldn't a fuse have blown if I had a dead short? Doesn't make a whole lot of sense. Any suggestions welcome.

 

Okay, problem solved!!

It was NOT a problem with the Electromotive unit. The XDi is working perfectly. Not a problem with relays, battery, fuses, coil packs, etc. All of that stuff is working perfectly.

So, the problem?? -- THE GROUND WIRE!! When I hit that bump, it must have caused the engine to shift enough that it partially pulled the ground wire out of its connector, enough so that it could not handle the load of all of the wiring to the XDi system that was running through it. It was not a total break, which would have been easy to diagnose. Instead, under load there was enough resistance that it was dropping the voltage in the XDi circuits down to between 8 and 9 volts, not enough for the XDi to fire the system. When we hooked up an alternate ground wire, the car fired right up.

Now I just have to rewire the ground. I spoke to Nick at Forza Ferrari and he suggested doubling up the ground wires. I'm going to do that, one to the engine, one to the chassis to avoid future problems like this. Just glad it was an easy fix.

While my friend Paul and I were trying to figure this out, we called another friend of ours who is great with this stuff. He said "Check the ground wires. It's almost always the ground wires." Well, he was exactly right. Good lesson that I'd actually learned a long time ago, but forgot -- 99% of all electrical problems are bad grounds. So tomorrow, I'm picking up some wire and new connectors and I'll be running new grounds for the system.

 

Thanks Eulk. BTW, while we are checking things out, I noticed that the old grounding strap from the engine to the chassis was looking kind of fraid. Since I have the car up anyway, I'm going to change that too.

 

I've heard about the ellusive sucker but don't know where it is. Where exactly can I find it hiding?

Thanks,
Steve

 

She's back up and running!! Hooray! Sweet sound of the Ferrari. I love it.