In the good old days, Japanese pilots would join their ancestors by diving their planes into our aircraft carriers. I think one of these pilots’ spirits is now dwelling in the engine computer in my 2003 Subaru Baja.
When I start it in the morning, it idles normally at about 650 rpm. However, when I’ve been on the highway for a few minutes, the idle rises to about 2000-3000 rpm, which is normally not a big problem except I live in the mountains of Colorado. On the steep downhill dive going into Denver, its like a suicidal dive into the Capital building downtown.
The car has otherwise been fine for its 180,000 miles of loyal service. Being rather cheap (my wife has noted this several times over the years), I have been working on diagnosing the problem myself. I have cleaned the idle air control (IAC) several times, and did resistance checks on the IAC, the engine temperature sensor, the transmission neutral switch, the TPS, and the air pressure sensor in the throttle body. All were great. I have checked everywhere for vacuum leaks using propane and WD40. Couldnt find any leaks, but I currently run the motor with every vacuum port capped to avoid even a chance that a leaky device or hose could affect its idling. The throttle cable has plenty of slack, and I have disconnected the cable going to the cruise control to be sure its not infuencing anything.
I broke down and bought a new IAC thinking it would help but it had no effect, everything was the same… Note that I bought an aftermarket IAC for a lot less that the dealer wanted. It was exact fit part, but maybe you get what you pay for?
The ‘check engine’ light has not turned on, either (except when it should, when you first start it). A friend lent me his sophisticated car scanner and it didnt turm up any trouble codes, but it did show one weird thing- when the car is allowed to warm up in the garage, the scanner shows the idle throttle position stays at 0%, and its idle stays at 650 rpm, all day. When you take it on the road, though, the high idle will manifest itself, and the scanner says the idle throttle position has crept up to 2%, and idle rpm is about 2000. Oddly, though, if you shut off the engine and restart it immediately, it usually goes back to 0% and 650 rpm…
I have verified continuity and voltages on all 6 circuits between the IAC and engine computer. So the IAC seems to be doing what the engine computer is telling it to do.
I can only conclude that the spirit of a long deceased Japanese pilot crept into the engine’s computer sometime when my car was being assembled in Japan, and he is trying to do our country harm by crashing me and it into the Capital building.
Could I be correct in this? what should I do next? A new car is not in the trade space - we are living on my pension, and I am far too cheap, anyway.