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The story has long been told that non-turbo cars from 1989 have bad ECUs. Something about them seems to cause them to fail. I recently looked at a 1990 car, whose owner complained of sputtering, bucking, and misfires while driving. I suspected arcing plug wires, because his car was a 1990, not an '89. But when I got listened to the engine run, I found something surprising. At idle, injectors normally make a nice loud rhythmic ticking. On this car, when one of the misfires occurred, I could hear the injectors issue a rapid series of ticking sounds, before returning to their normal cadence. I replaced the ECU with a known-good one, and the misfires disappeared and the injector ticking went back to normal rhythm.
The failure of his ECU (the start of this missing, sputtering, and injector arrhythmia) occurred after the owner's repeated attempts to jump-start the car. It had run fine the previous day, but it would not start (would only crank). He used a 50-amp jump-pack to resuscitate the car, and when it finally started, it misfired and sputtered because of bad ECU. I assume the ECU failed after shutoff, and would not start the car at all until a lot of current was put through the system. An alternative hypothesis is that he fried it doing a jump, but I find this unlikely, as his battery was fine to start the car subsequently. So it seems his ECU failed hard (no start) and then mended itself to the point where it caused only misfires, before I got a chance to look at it.
At any rate, this may prove helpful to those of us with LH 2.4, trying to diagnose a problem. If the injectors are ticking out of rhythm, suspect the ECU!
posted by 71.169.176...
, Mon, 14 Jan 2013 20:46:27
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