Hello there - could you please bring in a bit more car-related discussion to the thread? Thanks.
Farther up on this page I said I would be teaching my two best English students a few classes on car computers, specifically OBD-II systems. In English.
Of course, that meant I first had to teach them how a car worked. Transmission; drive shaft, differential. Then the engine. I started with a carburetor. The hard part for them seemed to be the Venturi concept. Bernoulli’s principle is not intuitive.
There was a picture of the insides of a motor, with no outsides. You know, crankshaft, pistons, valves, timing belt, etc.
Then I had the engine break out, a diagram of the four strokes of a conventional engine. I told them about the 14.7:1 fuel air mixture.
Then, I showed them a photo of a fuel injector and demonstrated how it worked with a spray can of Wal-mart 29% DEET Sportsmen insect repellent. Seriously, heh, heh. Hey, it worked!
That was a week ago. Yesterday, the older sister could not come. As is often the case Michelle showed up five minutes early. The reason this fact is so significant to me is is shows she is not bored nor stressed by my class. Triedaq knows what I mean. She admitted that when I asked her.
I started my typed materials with a block diagram of a basic microprocessor system, without the A/D chip which I explained in writing.
I had taken the mandated OBD-II tests from the Toyota Shop manual down to the beginning of the manufacturer optional tests. For each one, I listed the code in case of failure, gave my best shot at the type of sensor and how it supplied data to the microprocessor. Also, I attempted to explain the failure. And, when I knew of a car which had that code, I told her.
Foe example, months ago I scanned the city garbage pickup truck and found that coolant temp showed around -39 degrees, and it also had a crankshaft synchronization problem.
The one that gave Michelle the most problem was the piezoelectric knock sensor. But, I think at her age she can simply accept what I tell her without perfect comprehension.
We did not finish the codes in that 65 minutes. (Remember she came five minutes early.) At one point, we trotted outside to my Sienna and had the hood opened, looking in and talking about various things. I pointed out the throttle cable, showed her the foot throttle, and let her see the mechanism move when I pressed the throttle. We had already discussed the throttle valve and how it controlled engine speed by controlling air intake.
I explained the radiator and showed where the thermostat is located (I hope).
While we were studying under the hood, she looked startled. I looked around and her mom was walking by, and seemed to be happy to see what her 12 year old daughter was doing. Mom smiled, waved, and walked on home. She goes by a number of times a day, and thus with 6 kids still has the shape of a high school girl. I haven’t measured it but it must be a mile or more round trip with long hills. And, she usually has heavy food items, or even a grandchild in her arms.
Next Saturday, I will finish the codes and we will hook up the good scanner and see some live data. I want to induce a code, not sure what to do. I thought to loosen the gas cap, but I believe one has to do a drive cycle before it checks EVAP. Any suggestions for a quick failure with a quick reset?
I have to figure out something to put on my car floor so their clothes don’t get dirty when they reach under to plug on the scanner. Yes, it will be hands on as much as I can. I am that cruel!
I think next I will give them some machine language programs, having already looked at higher level programming and engine computer microprocessor diagrams. If I can find anything suitable.
I do have a 1940 Sixth Grade Alice and Jerry Reader (Runaway Home) as backup. 1940 Sixth Grade essentially means college level vocabulary today, so these kids are pretty good readers, in only one hour a week.
Unplug some sensor(s) . . . that should set some codes
Whatever sensor(s) you choose to unplug, make it appear that it IS plugged in. But make sure it does NOT click. Therefore, it will appear to be be plugged in, but is in fact open circuit
The engine can run quite well with certain sensors unplugged, because the PCM will use default values.
Hopefull, the MIL will be lit. Then your students can retrieve fault codes and look at the live data stream. Then they will analyze the data and hopefully find that unplugged sensor
Cool! That is what I was asking for. I Have to see where one is that I can access. There is one right in front on the exhaust manifold but I have to see where the other end is plugged in.
Last year, the heater on one burned out during our trip back to the Snow Zone. I went into a gas type station and the minute I started the car the CEL light came on. So, it should be fast. Thanks.
I probably won’t make them find the problem. I have not taught them diagnostic principles, but that is a good idea if we continue indefinitely. My goal is to keep them interested while advancing their English vocabulary
I’ll show them what the sequence is like, for now.