I like to know what my car is thinking. With human-human relationships, this is best fostered through a long and meaningful communication, a lifetime of time spent together. With human-car relationships (yes, there is such a thing), you can just plug in an OBDII device. I ordered mine for $15 from “China, China,” a couple of years ago, and it’s never failed me.
So last week after the idea emerged from my paranoid needle-watching that my WRX might be running rich, I plugged in the little Bluetooth box, paired it to my phone, and communicated. “P1086,” my car replied, sniffling a little. “No worries, little guy,” I said. “I can heal you. Just take it easy for now and stop dumping fuel.” I cleared the code and all was well. But I wrote it down, because it isn’t welcome back. This weekend, I set out to fix it.
After some brief Googles, I found that apparently the “Tumble Generator Valve” may be stuck open. So like any good mechanic, I replenished my supply of brake cleaner and went hunting. I started taking things apart. This was fun! Here was a valve-thingy on top of the throttle body. This looked like the cell-phone pic of a TGV I found online. And it certainly needed some cleaning. That’s weird. It has a coolant channel.
Another item I didn’t fix on Saturday, and one whose very own trouble code I swept away again with the 1086, was the Exhaust Gas Temperature Sensor, which does exactly what it sounds like it does.
What do all of these soon-to-be-abbreviated devices have in common? Two things: They’re all fairly useless emissions clamp-ons, and they can all screw things up for you.
The TGV is a cold-start item within the intake manifold. It’s designed to improve cold-start emissions in extremely cold temperatures, creating a vortex just after the fuel injector to improve the fuel/air mix for that tiny cloud of gas going into the engine. But unless you commute from the upper stratosphere or Antarctica, it makes very little difference. Except when it throws a code and starts trolling your fuel maps, spending extra fuel where it isn’t needed. Then it makes a negative impact on the environment.
The IACV isn’t so useless, but has a useless element: the coolant line running through it. Air density varies with temperature, changing your car’s ideal idle speed. The IACV regulates how much air gets into your engine. Now, at most climates, the coolant line proves more of a hindrance than a help, heating the air that runs into your engine (which, as any intake tuner will tell you, is bad), but never needing to unfreeze much at all.
Instead, the IACV freezes at all climates with dirt and grime, a product of the oil always running into the throttle body via the PCV system, requiring you to clean it out, wasting your precious cotton swabs and initiating your quest for rare, face-shaped gaskets. Yeah, don’t get me started on the PCV.
Side note: If you really want to improve your car’s emissions performance, don’t leave it idling for more than 30 seconds, not even to warm it up. A car warms faster at higher RPMs, anyway.
Least intrusive in this band of emissions misfits is the EGT sensor. Think of it as the O2 sensor’s sidekick, reading the temperature of the exhaust instead of the contents. It’s still a pain to clear that code, but that’s the worst of it, and it can’t remap your fuel injectors like the O2 sensor.
Thankfully, there are ways to bypass all of these systems, and in most climates, there’s no consequence. It’s another way of communicating with your car, I guess.