I have a pretty lengthy history as a mechanic and in all of my years I’ve only seen 2 bad ECMs,
One was an ECM that was very questionable on a Subaru.
The other was on a Volvo and believe it or not, it was killed by a bit of orange juice from a Donald Duck can of juice. The ECM was under the passenger front seat. The owner was a traveling rep and frequently threw things into the passnger front floor. The near empy can of juice rolled under the seat and the remaining bit of juice oozed past the ECM connector onto the printed circuit board where the acid ate up a dime sized bit of the circuit.
That led to the injectors staying open all of the time, belching black smoke, and running like garbage. Took me a while to sort that one out and probably ranks as the weirdest failure cause I’ve ever seen in my life.
read the above for a better understanding of that malfunction code. Not to belabor the obvious but the ECM did identify the cylinder fault, like others I very much doubt yours is bad. A lot of other more likely possibilities exist.
Thank you much for sharing your experience and expertise. The evidence is mounting that the likelihood of a ECM failure is very remote. I really like my FX35 and I’m getting an invaluable education for more effective future maintenance. Do you think I should restrict future repairs to a dealer or those who specialize?
A friend of mine had his Subie in a flash flood, where him and his wife went into some shopping center and the big rainstorm came in while they were inside, so they exited to the bunch of cars FLOATING in the parking lot. He said that after few hours water finally came down and he was able to drive away on his 200+K miles Subie, but ever since he had weird stuttering time to time and other things, which went away with replacing ECM.
Not seeng any description of operation info for the FX50 listed for 2007, no FX 50 for that year, but on the FX 45 using a 4.5L V8 engine the computer uses these input sensors to determine when to fire the coils:
crank position sensor, cam position sensor, mass airflow sensor, engine coolant temp sensor, throttle position sensor, accel pedal position sensor, knock sensor, park/neutral safety sensor, wheel speed sensor.
So a fails to start could be any of those, in addition to a battery/wiring harness problem. To fire the coil the ECM outputs a low power trigger signal directly to the coil. Inside the coil ass’y is a power transistor, which is what provided the high electrical power needed to fire the coil and produce a robust spark at the spark plug. Usually when there’s a failure on a PCB it’s in the high power area of the circuit; but the high power part of the ignition circuit occurs at the coil , not on the ECM.
The first step in the diagnosis is to probe the ECM’s output trigger signals to the coils, using a lab o’scope. If there’s no signals output, next step is to investigate if there’s an input that’s missing. The most likely missing inputs that would cause a fails to start are the crank position sensor (which would usually cause a cranks ok but won’t catch and run) and park/neutral safety sensor (which would usually cause a fails to crank).
Another idea, since this happened soon after a repair, it could be something as simple as a ground connector coming loose b/c it wasn’t properly seated upon reconnecting everything back up.
Just a thought but could his issue be related to a bad pcv valve? I think his might have two of them. On a 2007 his might still be original, and gunked up.
Thanks so much for that vital info. I didn’t know there was such a place and having that info turned the tide. I contacted “SIAELEC” followed their instructions for getting the repair and the car is now running great. The problem turned out to be both the ECM and the ignition coils. When reinstalled the repaired ECM produced additional codes revealing that (4) ignitions coils had to be replaced and that they were most likely at the root of the problem. It was an rather expensive repair but that’s a darn sight better than ending up with a useless vehicle. Thanks so much to you, all the members with great advice and the “Car Talk Community” for providing this invaluable service.
old Donal Duck excuse