Haunted Car?

Can a car be haunted? On a muggy night in South Africa in 2004, a Renault Megane turned itself on and began jumping backwards, all on its own. This car is notable because there were several witnesses and news reports. Nine people, including two police officers, heard the Megane's engine start before it "jumped" backwards twice uphill, according to officials. The car apparently roared to life on its own, despite having no keys in the ignition and the parking brake engaged. I thought the 2006 Lincoln LS with a 3.9 was haunted. It came from Shepherdstown, a nearby town so haunted that the local police called in “Ghost Hunters” from the TV series. The LS Sport came from a couple of different shops for intermittent misfires, stalling, MIL on and transmission shifting issues. The work history indicated the plugs were replaced, TAC module was replaced, The PCM was replaced multiple times, the fuel pump replaced and coil assemblies were replaced. The throttle body was cleaned. Road test #1 resulted in an engine stall—just like the ignition was shut off. After the vehicle restarted, a P0607 flagged. The PCM’s internal CPU has encountered an error. This could be a calibration update, or aftermarket performance parts installed, or a damaged PCM. Clem came back with another PCM (number 3) and wants me to install it. I said no way. I did a visual inspection first, especially focusing on the PCM considering it was replaced before. Guess what? I found a damaged CAN (+) wire had several broken strands. I did a wire repair, confident that this was a major issue. I continued testing, though. I checked the ground circuits first. I prefer testing the ground circuits first because the remaining circuits will use this ground to verify they are working correctly.  This includes battery cable connections, which are subject to corrosion. No trouble found. Once the grounds are checked, I then move to the voltage circuits starting with B+ voltage because the Ignition, voltage reference, and control circuits require a functioning B+ circuit. B+ is direct battery voltage to a module or component. Those circuits were good. I checked the ignition circuits which includes ignition circuits that pass through a fuse, module, component, or connection.  When testing ignition circuits, I referenced the wiring schematic as to the ignition switch mode or position needed to achieve a valid reading. The ignition circuit test is referenced to the ground or low reference circuit and requires a functioning B+ circuit for a viable test. I checked the reference voltage circuit next, which is referenced to the ground or low reference circuit and requires a functioning ignition circuit. Satisfied that all PCM circuits were now acceptable, I moved on. Road test #2 flagged a P1270 (Engine RPM or Speed limit reached) and P2112 (TAC Control System). I checked data PIDs IACTRIM and IACKAM2. The sum of IACTRIM and IACKAM2 is the total IAC. Total IAC was 0.54 lb/min. I removed the throttle body and cleaned the edges of the throttle plate and throttle bore. It was bad. I reassembled it and took the vehicle on road test #3. This one resulted in an engine stall—just like the ignition was shut off. After the vehicle restarted, a P0607 flagged. The PCM’s internal CPU has encountered an error. This could be a calibration update, or aftermarket performance parts installed, or a damaged PCM. Clem wanted me to install that PCM. I said not yet. I already checked for the common bad coil issue. I always check the Coil-On-Plug ignition systems for defective coils by back-probing the main coil B+ with my PicoScope on glitch capture and using an injector as cylinder reference. I put the coils through the tests, including idle testing, cold, hot, snap throttle and power braking. With throttle cables gone, plus the 6-way BPPS, it is tougher to check these functions under the hood. I always look for a positive or negative voltage spikes on the coil ignition feeds which will indicate the failing coil(s). This car passed this test with absolutely NTF!

“This car is haunted,” Clem said.

“I have to walk away from it for a while,” I said.

“You can’t fix it?”

“No—I haven’t fixed it. I don’t throw in the towel but I do need a break.”

I thought about it while watching the Shenandoah River go by. A shop said they cleaned the throttle body and I could tell they didn’t. Did they even change the plugs? That was on my list of things to do when I would tackle it again.

“You must have one heck of a load, Bob, with all those cars and trucks to diagnose,” Clem said.

Then it hit me. I smacked my head as a token gesture.

“One heck of a load—you are so right, Clem!”

“Huh?” Clem said.

I got out my extra long test leads and went for a test drive. And I caught it--an ignition voltage spike! Right after the spike I lost the injectors. I also wanted to check that TAC module issue. With my PicoScope hooked up to ignition primary, and both throttle position signals (one on glitch capture), I captured a voltage spike on the TPS signal. The voltage spike is what caused the TAC codes.

The coil failed under a heavy load, hitting the PCM with the spike, causing it to reset.

More history of the LS Sport surfaced. The fuel pump was replaced because the original owner jump-started the car with a heavy-duty diesel truck charger on boost. Why did he do that? Because he was tired of the old battery going dead, procrastinating on buying a new battery, and after the original battery would take a charge, he decided to boost it. After that, he noticed the PCM would not drive the fuel pump so he had the car towed to a shop and had the technician replace the fuel pump.

The COP units were replaced, but a new one was bad to begin with, failing only under very high load. The ghosts were finally “exorcised” from the Lincoln.

I was so happy to get this one diagnosed.

“How can I thank you?” Clem was elated and hugged me and kissed me on the cheek. Now, don’t think that was weird. Clem is short for Clementine.

“You can really thank me by paying my bill, Clem,” I said, handing it to her.

“Now—that’s scarier than any ghost,” she said, after seeing it.

“I can put the ghosts back in the Lincoln, then.”

Clem paid.