No Fire, No Go

No Fire, No Go

I had recently purchased a 1984 BMW 318i with 196,000 miles. Buying the car with very little mechanical knowledge or experience – but trying to buy a car that would make a mechanically solid track car – was mostly a matter of luck. After only owning the car for a week or two, the jury was still out on whether I was lucky or not. That's when the problems started, and my heart fell – this relationship wasn't off to a clean start.

The problem began with the car running rough – really rough one afternoon shortly after the "First Date". I had no idea where to start, but it was clear There Was Something Wrong. On the highway, the car jittered and gasped and had very little power. I didn't know where to begin, and hoped (vainly) the problem would just go away. If I had the (limited) mechanical knowledge that I now have I would have quickly been able to isolate the problem to be an issue of "spark" – the car wasn't getting a clean or constant spark on at least one of the cylinders. Internal combustion engines are all about that – combustion – and as I learned in boy scouts (okay, so I never was in boy scouts, but playing with aerosol and matches out in the woods is practically the same thing. Don't do that at home.) to have combustion you need Oxygen (air), Heat (electrical spark) and Fuel (gas). Without the right proportion of these ingredients, the engine won't run smoothly. As I've since learned, a big part of "tuning" an engine for more power comes down to how to get more of those ingredients while keeping proportions constant and making sure the combustion happens at the right time (and yes, a double-decker rear wing with neon lights directly contributes, as do "Mugen" and "No Fear" stickers. So does driving with your seat REALLY far back and one limp wrist over the steering wheel. Its very sophisticated theory. Stephen Hawking can probably explain it, but I'm not smart enough).

The next day, the car wouldn't start at all. It wouldn't even turn over. It just made a little "clicking sound" every time I turned the key – something was trying to happen, but it wasn't working. My heart fell – this was it – I'd just wasted $1500 on a junker, exactly what I was hoping to avoid. I took a deep breath and looked in the Bentley book that had come with the car. When I flipped to the "engine" chapter it provided a brief overview of how engines work (fire, oxygen, fuel and lots of expensive, fragile whirring bits), but didn't shed any light on start-related problems. Looking further, I found a section on troubleshooting hard to start problems. Phew – troubleshooting – finally something I understood.

Troubleshooting 101: be methodical. This is something I've learned from many years of broken computer hardware and software. If you're not methodical, you'll likely overlook the cause of the problem. Try the most likely stuff first. If you must buy parts, buy the cheapest ones first, and try to be as sure as possible before you spend any money. Most critically, think logically – mechanical (and especially electronic) systems work in a logical and understandable manner.

The first test I tried, recommended by the Bentley manual, was to pull out the number 1 spark plug, set it on the valve cover so it was "grounded" and attempt to turn the car over. A blue spark would mean that the "heat" element of the combustion triangle was adequate. I got no spark at all. The manual advised me to troubleshoot the car's electrical system, and provided a series of steps for how to do this.

The first thing the troubleshooting guide in the manual talked about was a multimeter. I went and bought an automotive multimeter at Sears for under a hundred bucks. A multimeter is an electronic tool used to test various kinds of circuits. It has a dial that sets what kind of testing you want to do, a read-out for results and two probes for the actual testing.

Based on the guidelines in the Bentley book, I began testing circuits one by one. The first evening of testing, every circuit tested with a result that was within the spec listed in the manual. At least I could tell that the multimeter and my tests were valid. But I didn't find any problems. Because of my lack of familiarity with mechanical or electrical systems of any kind, a lot of my time was spent trying to figure out what the basically clear instructions were actually talking about. Additionally, I worked very slowly, triple checking everything to avoid making stupid mistakes (okay, so I made a lot of those – to avoid making expensive mistakes would probably be more accurate). Half-way through the second evening I found it – testing between the little Bosche ignition unit mounted on the firewall and distributor's "impulse generator" there was no juice. The distributor is a electrical-mechanical system that "distributes" a properly-timed spark to each cylinder in turn. This was a strong candidate for the problem.

Following the instructions in the Bentley manual, I pulled the entire distributor out of the car. I managed to mangle the distributor rotor (one of the whirring bits, luckily one that's not so expensive) while I was at it – it was time to replace it any way. Continuing to follow the instructions in Bentley book, I disassembled the entire distributor on my living room coffee table (which wasn't a very popular place with my girlfriend, I discovered). This is also where I discovered what a "snap ring" was. If you don't already know, it's a tiny piece of metal used as a clip with the express purpose of being absolutely impossible to remove and even more impossible to put back on without the use of a specific tool (snap ring pliers, which is basically a pliers that works backwards – when you squeeze, it opens). The "impulse generator" turned out to be a small plastic donut. Since I'd already destroyed the rotor, when I went down to the local parts counter the next day, I just decided to replace everything on the distributor except the metal housing. It ended up costing close to $200. Ouch! I was very pessimistic as to whether this would actually fix the problem. After all, I'd never fixed a problem with ANY car before (unless you consider "low on gas" a problem).

A week later, the parts came in, and I set about rebuilding the distributor. I also made a point of thoroughly cleaning it. Essentially the distributor is a set of small electric and mechanical parts that are stacked one on top of the next around a central shaft. It looks kind of like a giant ice-cream cone. The central shaft is driven by the rotation of the car's motor, and makes everything in the distributor spin (whirring bits). Putting the distributor back together was pretty easy, but it took me a good three hours to realize I needed one of those snap ring pliers-thingies (especially since I didn't actually realize such a tool existed before destroying my new snap-rings. Which are, luckily, twenty-cent parts.)

I took the completed distributor and stuck it back in the hole from whence it came, being careful to keep it close to TDC (TDC, aka Top Dead Center, is an arbitrary point that indicates that the #1 piston is at the beginning of its four-stroke cycle). Whenever you do ANYTHING to the whirring bits on an engine, it's critical to keep everything at TDC. Otherwise, the whirring bits run in to each other at really high speed and cause a big mess.) I tried to start the car. Nothing happened. Whoops – forgot to reconnect the positive battery cable. Once I did that, a miracle happened. The Quest for Fire was successful! The car started – although it ran poorly. This was easy, though, according to the Bentley manual. On the old M10 engine, the timing of the engine (when the spark happens vs. the stroke of the piston) is modified by rotating the entire distributor housing. Easily done. I rotated it clockwise (advanced the timing) about 45 degrees until the car was running smoothly.

This was when it happened: I felt really good. I had just fixed a serious problem with my car with nothing but a book, a little luck and some common sense. Maybe it's a guy thing (although I don't think so), but there's something deeply satisfying about making something broken work like new. I realized that if I could do this, I could do just about anything to this car. And I had saved several hundred dollars worth of troubleshooting and labor costs from a professional mechanic, even after buying the multimeter.

I haven't had a problem with the ignition system since. The car starts instantly – just like it did when it was new.