1988 Buick LeSabre Minor Disasters

Okay...a younger brother of mine is driving this car and it develops a miss one day out of the blue. Cylinders 1 and 4 are definitely not firing, and they both share the same tower on the coil pack. Plugs and wires are good. This should be an easy fix!

This car has the "Magnavox" type of ignition system with the three coils in one unit on top and the control (?) module on the bottom.

He replaced the top half of the module and everything was fine once again. But while doing so, one of the wires got snagged around a screw and its insulation was damaged. The system somehow put up with this and ran for quite some time before the car just dropped dead and stalled out later that day. Examining the potting compound showed that the bottom half of the unit had simply overheated. A new lower module was obtained and the car fired up again as soon as I was sure no more wires were being pinched. It was not running properly, and somehow it turned out that two spark plug wires were swapped. I fixed that.

Now it definitely runs better, but it is not right. It starts easily. The exhaust smells heavily of gasoline, it lacks power, and is consuming way too much gasoline while running. Given that two plug wires were somehow in the wrong places, I can't help but think that some of the other wiring (what goes under the module) may be incorrect. The instructions that came with the coil portion aren't unquestionably clear as to which wires go where. It shows two possible configurations, and I simply don't know which one is correct.

Any help would certainly be appreciated. I think what is really needed at this point would be a description of what wires go where when connecting the coil module to the lower portion. I'm hoping that this little wiring disaster hasn't blown something else...

William

Reply to
William R. Walsh
Loading thread data ...

I presume the check engine light is on if it's running that poorly. Have you checked for codes? How many miles on vehicle? Anything else recently replaced?

Reply to
James Goforth

The problem is now fixed.

Yes, the service engine light is on, but it has been for a while because the camshaft position sensor is seemingly not reporting valid data and therefore the ECM cannot enter sequential fuel injection mode. (This is the code it reports, the sensor and its wiring seem to be good, and that's the furthest I've gotten with it. Examining the trigger for the sensor doesn't look to be fun or easy. I'd like to fix it, but the car runs fine in its present state and I have more than enough to do already.)

I started to suspect the top half of the module, so I did some resistance tests on both the primary and secondary sections of each coil. All the primaries tested good, but only two secondaries were good. The last one was open. Looking at the upper half under bright enough light reveals a nasty crack that appears to have been caused by the heat developed when the lower module was shorted to ground. It travels up the coil tower quite a ways and gets thinner, suggesting that as the heat tapered off, so did the stress that caused the crack.

A new upper module was obtained and installed. The car now runs perfectly once again.

This has proven to be an expensive lesson for my brother. I just hope he's more careful next time...

William

Reply to
William R. Walsh

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.