Hi I have an 1990 Buick lesabre with the 3800 engin... The engine is only getting spark on cylinders 3 and 6.... Initially it had loss of power and backfired through intake after the car heated up but the other day it fell dead and wasn't getting any spark I replaced the crankshaft sensor now its only getting spar on 2 cylinders I bought a new coil pack and had the module ... There is no check engine light although it was on when I bought the car I'm at a total loss right now and could use all the help I can get pleassee

OK, first of all, the fact you had spark on a couple of cylinders, means the cranks sensor is ok....if it was bad, you would have no spark....

You say you have a check engine light on....you can check for codes by jumping A to B in the ALDL connector, with the key on, engine not running, and counting the flash codes to retrieve the codes....


I assume you have 3 separate coils, as opposed to one coil with 6 terminals?

You bought one coil? How did you determine it was bad? What you should have done was, if you had spark from two terminals of one coil, swap it with another....if you still had spark on the same two wires, you know that the coil you swapped, was good....

What I would do, is disconnect the wires(label them if not numbered), and remove the coils(mark them so you know which way they were on the ICM).....

Each coil is attached to the ICM by two terminals......get a test light...attach it to the first set of terminals, and crank vehicle...the test light should flash.....do the same for the other two sets of terminals.....they should all flash.....if none flash, either bad crank sensor(but you say you replaced it with a new one), or bad ICM, or wiring in between.....if one set of terminals flashecsc, but either one or both of the others doesn't, you need an ICM.....If they all flash, then you have a coil(*) problem.....

Its magnavox type one with one big coil pack I got two different icms tested and the both tested good could it have jumped timing?

Even if the timing "jumped", you would still have spark on all cylinders......

So you have the Magnavox coil.....one quick check is to take a secondary resistance reading of all three pairs of coil.....I believe they should all measure between 9K-12K ohms(9,000-12,000 ohms), depending on temp.....higher the temp the higher the resistance from the coil......they should all be withina few hundreds of each other.....for example, let'* say you test a coil on a cold engine.....one pair is 9.6K, another is 9.4k, but the third is 12.6K or even higher....that coil pair is bad, and unfortunately the whole coil has to be replaced......

So, did you do a coil output test of 1/4, 2/5, 3/6? Did they all spark?

If one or more didn't, remove the coil.....you will find one line with three connectors on it.....then there will be three different colored lines with one connector on each......attach one end of your test light to the line with three connectors(attach to any of the three connectors)...... you will then attach the other end to one of the single wire connectors......crank the vehicle and the light should flash.....disconnect from the single wire connector and go to the next single wire and attach.....crank vehicle, light should flash....do the same for the last wire......if all three wires flash, ICM is ok, and you need a coil.....if one or two wires do not flash, you need an ICM.....

Only sparking on cylinders 3 and 6 .... What ever the culprit is was overheating because when the car got hot it would always misfire

Really? T2 gave you a detailed description of what to look for and that'* what you come back with?

Switch the 3/6 coil with the 1/4 coils and see if the spark moves to cylinders one and four. If it does, you need two new coil packs. Marginal coil packs can misfire when they get hot.

2kg4u, he can't, he has the single Magnavox coil......but he can do the test I showed him....