Computers in Cars

Yesterday I had to take my car in for its annual emissions test. When you buy a new car in Utah, you only need an emissions test every other year until it gets to a certain age. Then you need one every year in order to renew the registration. My car is old enough to require a test annually.

There are a number of places you can go to have the test done. I have a favorite place I have been taking my cars to for decades. They don't do anything other than emissions tests and the state restricts what they can charge for the test. Once the test is completed, the state has an immediate record if it passed or not. When it passes, I can log onto the state website and can see that information, pay the registration fee, and wait for the state to mail me my license-plate decals.

Yesterday I drove to the state test site and waited my turn. I didn't have to get out of my car, I just drove to an open garage door and waited for the car in front of me to complete its test. Then the service technicians waved me into the waiting bay. They connected a cable to my car's OBD-II port and my car's computer gave them all the information. A few minutes later the test completed and I found out I passed. I drove out the back of the garage bay and the guy waiting behind me pulled right in.

I remember buying a new car a couple decades ago and having the salesman tell me that the rapid rise in automobile costs had to do with the addition of new computers. Those computers have helped increase the reliability of most engines. They can tell you when a part has failed and needs to be replaced. They can also tell you how much your car is polluting. It is good that states around the country can tap into that information without any difficulty and help keep our air clean.

I left my house yesterday knowing I needed to get my car's emissions tested. Only twelve minutes later, I returned home with the task completed and ready to submit the results to the state. This is one case where computers have helped create efficiencies in my life. Hopefully you feel the same way.

Home for Christmas

Yesterday I made it home after a very adventurous drive. Even after all of my preparations that my wife thought was overkill, I still had a number of unknown variables to deal with. My Jeep had no problem in the snow as I crossed the Sierras on I-80. I did have to stop at the chain control station but the guy waved me right through as he saw I was in a 4-wheel-drive vehicle with awesome snow tires. I was glad I knew where the cheap hotel in Reno was. A word of caution though, the price of the room was only about 60% of the total cost. There were a number of taxes and fees. My $25 room ended up costing $36.04. It was well worth the price as having to spend the night in my car was not something I was looking forward to. I also got a hot shower in the morning.

The real adventure happened after I got through the expected hard part of the trip. My Jeep threw a "check engine" code when I got into Reno. I didn't think anything of it as it was one of those you-can-ignore codes. It turns out, I shouldn't have ignored the code. The engine was running too lean and it was causing problems. Every time I stopped for gas, it would throw a code and the car would struggle to stay running. I would clear the code and the car seemed to run fine only to act up 100 miles later. Eventually I figured out what was going wrong. Whenever you car illuminates the "check engine" light, it runs the fuel a little richer. Your gas mileage goes downhill but the car still runs. Even though you turn off the light, it still runs a bit rich for the next 90 or so miles. I knew this was the case but didn't figure it out until I was about 200 miles from home. Then I left the service light on and limped home. I was glad to pull into my driveway and know that I don't have to go anywhere for the next 20 days.

I still have to work for the next few days but I get to do it from home instead of out in California. That will give me plenty of time to track down the problem on my Jeep, play a few video games, and spend a lot of time skiing.

A Tale of Two Projects

This past weekend I spent time digging a giant hole in my front yard looking for a water main break. Fortunately I found the problem on my first hole as there were two likely places the leak could have been. Once I found the problem but before fixing it, my son decided he would try and resolve a problem with his car. In the process he learned that you never start another project until one is complete. As the water was off in the house, he couldn't wash his hands after working on the car until the first problem was completely solved. He also managed to break both his car and my other son's car in the process and so at the end of the afternoon, we went from having one project to three.

My son's problem was actually fairly simple. In the process of replacing the cylinder head on his 1996 Jeep Cherokee, we broke one of the temperature sensors that screws into the the engine. My son wanted to replace it with a new one and so he went to the auto part store. He immediately broke that sensor in the process of trying to put it in. Naturally that was the only one the store had. Fortunately he was able to bring it back, get his money back, find another sensor at a different auto parts store, and break the new sensor. Another trip to the second auto part store and he got another one. Yes, the temperature sensor is incredibly brittle and breaks easily. One would think they would make them a bit more resilient.

The 1996 Jeep Cherokee actually has two engine temperature sensors and the one my son kept breaking is the one that sends information to the temperature gauge on the dashboard. Unfortunately the new one told my son that his engine was overheating and so my son couldn't go out with friends that evening. He was pretty bummed. When we popped the hood and checked the engine, it didn't seem any hotter than normal and didn't have the usual signs of the radiator boiling over. So we needed to determine if the engine was really overheating or if the temperature gauge was bad.

I'm a firm believer in the saying that "A man with one watch knows what time it is, a man with two isn't quite sure." In 1997, the engineers at Jeep decided the second temperature sensor in the Jeep Cherokee was superfluous and removed it. Fortunately for us, our job was to tap into the second sensor on my son's Cherokee and see if it was giving the same high-temperature results. All we needed to do was to tap into the car's OBD-II computer. Fortunately my son has a code reader that is a little more sophisticated than mine and it reads various parameters that include the engine temperature. The only catch is that the car has to throw a check-engine code first. My son tried unplugging various sensors only to have the engine keep running without any problems. He even tried unplugging one of the spark plugs with no luck. Finally he pulled the plug on one of the fuel injectors and the car threw a code immediately. He checked the code and the engine parameters and discovered that the engine was in its optimal operating temperature. That means the gauge sensor was wrong and his car really wasn't overheating. We now know why the engineers at Jeep took out the separate gauge sensor and just use one now.

The weekend is over and the hole in my front yard is now filled in. My son's Jeeps is running fine and the erroneous temperature gauge seems to be fixing itself. My son has also fixed the problem that arose on my other son's car. It took a couple of days, but things seem to be back to normal. At least until the next weekend.