Firing Order: Modern 4x4 Technowizardry (And My Carburetor Icing Story)Posted in Features on May 15, 2017
New 4x4s today are loaded with some serious modern technowizardry. Recently, I’ve been thinking about technology and how it has changed our 4x4s. Even base-model 4x4s are packed with it. Personally, I think I’ve gotten jaded to it, but every once in a while I get grounded by thinking about my ’84 Jeep Cherokee XJ that I owned in the mid-’90s. It reminds me that even fuel injection is awesome.
The Cherokee was powered—and I use that term loosely—by the 2.5L four-cylinder engine, which, by the way, had its own litany of problems. One of the carb’s problems was icing. I lived in northern Illinois, and when the temperature dropped below 0 degrees or so, the engine wouldn’t start sometimes. It was a crank-but-no-fire problem, but it wasn’t consistent. This was vexing to me at first. Eventually, I figured out that when I drove the XJ in very cold weather, the carb was icing. When I shut the engine off, residual engine heat would melt the accumulated ice onto the choke linkage, and because the vehicle was parked outside, it would refreeze as the engine cooled and lock the choke in the open position. The system didn’t have the oomph to overcome the ice and close the choke for a cold start. What made it initially hard to figure out was that on some below-0 mornings the engine started with no problem. Diagnosis: Those were the mornings preceded by warmer weather where ice hadn’t built up on the carb while I was driving.
I never did figure out a way to stop the icing, so I lived with it. It’s been many years, but if I remember correctly, the routine on cold mornings went like this: open the driver door, get inside, pump the gas pedal, pull the hood release, exit the XJ, open the hood, unscrew the air cleaner assembly nut, lift the air cleaner assembly up with one hand while using the other hand to manually break the choke free of its icy cocoon, refit the air cleaner assembly and then tighten up the nut, close the hood, re-enter the XJ, and start the engine. This process often had to be repeated numerous times a day if I was using the vehicle to run errands when temperatures were very cold. I was surprised at how fast the freezing process would occur after shutting the engine down. Naturally, this process was annoying because it was cold outside and this process took time (I can hear those of you that live in warm climates snickering right now).
One cold winter night I went to a monster truck show, and as usual, the choke had frozen by the time the show was over. I went to begin the process of freeing the choke, but the hood latch was frozen. This was a brand-new quandary because a key piece of my finely tuned process wasn’t cooperating. As a bonus, the XJ was parked in a remote parking lot and almost everyone else had left because I had hung out to talk to the monster truck drivers. It was one of those brutally cold nights, around -15 degrees. As I sat in the driver seat and pondered my options, I watched as my exhaled breath hung in the air of the frigid Cherokee, slowly evaporating. The windshield began to frost up. I began to frost up. I don’t remember how, but I somehow got the hood of the XJ open, which allowed me to complete the choke unsticking process.
I traded the XJ in on a new ’97 Jeep Wrangler Sport a few weeks later and enjoyed that the fuel-injected 4.0L engine started without complaint on frigid mornings. That tech left me all warm and fuzzy, which was the opposite of what the XJ’s carburetor left me.