atomic_fungus (atomic_fungus) wrote,

#6196: How do I know that I'm zeroing in on what's causing the shimmy?

Today I had to go to the bank, to check something in the safe deposit boxes. I went out to the driveway, got into the Jeep the same way I have nearly every day for six years, and started it--and it ran like shit.

Now, over the past couple of weeks, I've noticed an occasional stumble at idle. Sitting there at a traffic light, for example, and blup there'd be a little shake of the vehicle. This is what happens when there are approximately 50,000 miles on your spark plugs, right? You won't get a glass-smooth idle, not even with a modern emissions system, when your plugs are old.

Today, though, it was stumbling badly, shaking, no power--and it didn't stop until I put it back in park and revved the engine past 2500 a few times. It smoothed out, so off I went--but even then, when I got to the stop light, it was stumbling in idle, just not as badly as it had been.

After going to the bank, I went to the auto parts store; bought a can of Seafoam and had them check the codes for me. "Misfire on cylinder one" was the result.

Now: a misfire which happens on only one cylinder in a port-injected engine can have three causes. 1) The fuel injector is not working correctly. 2) The spark plug/ignition is not working correctly. 3) Bad compression.

The can of Seafoam ought to rule out #1; having dumped the entire can into the tank and filled it (at $3.10 per gallon of course, it was $2.90 yesterday, argh etc) that should be enough. I know Seafoam works; I was an instant convert when I dumped a can into my 1985 Fiero in 2002, and saw an immediate improvement in how it ran and idled.

If that doesn't fix it, of course the next step is to replace the plugs. WTF--they're due anyway, and they're like $2 apiece. I can't do that today, and Sunday's spoken for already, so probably I'll do that a week from today. Along with fixing the rear brakes, and maybe even the exhaust, which is also still in need of work.

And if that doesn't help? Do a compression check--but a bad result here means that the Jeep is pretty well done. Rebuilding the engine would be cost-prohibitive; the red Escort engine job was about $500 and it was actually more than the car was worth. (I really enjoyed it, though, so WTF.) If it were something simple like a bad lifter I might get away with replacing it, but more likely not--and considering that the Jeep has almost 181,000 on it?

I'd have to look at the title to know what miles were on it when I bought it. Something under 85,000; I think it was around 84k and change. In 11 years I've put almost 100k on it; I'd like to drive it further if I can. We'll see, I suppose.

Going to "bad engine" too quickly, without a compression check, would be dumb. Okay: in 2007, for my Dad's funeral, my late sister, late brother-in-law, and their two kids came out here in their Subaru. On the day they were to leave, it began running badly--on only two cylinders--and I rapidly found (with some help from friends on Pennock's Fiero Forum) that the coil pack had gone bad. Replaced it, changed the oil, good as new for the ride home! (And thank God it didn't do that when they were traveling!) The Jeep uses a coil bar, but it's the same approximate electrical configuration, and that coil bar has--again--181k on it. It's probably not a cheap part but I'd wager it's less expensive than rebuilding the engine.

Replacing the fuel injector would be pretty cheap, too, if that turned out to be the problem. And it could just as easily end up being something electrical, like maybe I didn't put enough dielectric grease on that spark plug and now it's got some corrosion, or the fuel injector wiring needs a little fixing, or-or-or.

So the best thing to do is "wait and see"; I've made a change to the conditions (fuel system cleaner) and we'll see what happens. That's what I can do; that'll have to do. But it does put everything else onto the back burner.
Tags: #1

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