View Full Version : 98 Buick Century 3.1 Firing order in Haynes not consistant with markings on Ignition Module??

07-21-2011, 08:27 PM
On my 98 Buick Century 3.1 my Haynes Manual shows a firing order on the coils of 5,2,3,6,4,1. However, I am replacing the ignition module and I see that the order which is marked on the old module as well as on the new module is 2,5,3,6,4,1. I recently replaced the left coil which seems to be marked backwords in Haynes, (but I hooked up the wires as Haynes instructed), and now about 6 weeks later the ignition module went out and the same left coil is cracked on the side. I need to know if I should hook up the wires according to the numbers on the ignition module (2,5,3,6,4,1), or if this module going out was a freak occurance and I should put them the same way Haynes instructed (5,2,3,6,4,1) again and assume that I was sold a faulty coil.
Also I want to note: I put my multimeter on the terminals on the ignition module to test resistance, and the multimeter would only give me a reading if I put the poitive and negative leads on a certain way. This worked for the middle (3,6) coil and the right (4,1) coil, but when I tested the terminals for the left (5,2) coil, I had to reverse the polarity on the leads of my multimeter, in order to get a reading. PLEASE HELP ME!

07-21-2011, 10:33 PM

I checked with the factory service manual and found that the coil is numbered the same way as in the Haynes manual. But really, it wouldn't matter if you swapped the wires as long as each pairing of wires is connected to the proper coil. This is because the ignition system uses what is known as a "waste spark" system - each set of companion cylinders fires simultaneously (one coming up on the compression stroke, the other on the exhaust stroke).

07-21-2011, 11:50 PM
Hi, I went ahead and plugged the wires accordingly, as directed by Haynes, with my new Ignition Module. My car is running like a champion! I am grateful for you checking into this for me--I was concerned that having those two wires backwords would cause future problems, but I trust they won't. I'll just have to return my cracked coil pack to the auto parts store, and assume that it was a manufacturer problem. I have always purchased a Haynes manual for each vehicle that I purchase, and I have used this forum today for the first time. Your work today has made me appreciate Haynes all the more! I'll always recommend your books, and now, your website.

07-22-2011, 02:13 AM
Well thank YOU! I'm glad your car is running well now.