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Proper firing order of a 85 GN

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billygeg

Member
Joined
Oct 5, 2009
Messages
440
Hey guys.
I need the proper firing order for the 1985 GN...I have a few different print out sheets showing different firing orders and I am getting confused here. Both print outs are for the 85 GN...Either one of the printouts is wrong or I'm nuts! I need to know which wire goes to which cylinder. I'm no mechanic but I always followed the power coil one cable goes to cylinder 1, 2 cable goes to cylinder 2 and so on...Thats how I always remember it being and cant see why it would be different. looking from the front of the car I need to know which prong is which number on the cap and which plug it goes to..If anyone can help me out I would really appreciate it. Please dont send the links with pictures. I have printouts from them already and they are doing me no good. One link shows one way of wiring and another link shows a different way and they are both for 85 GN so I dont know which is correct, So dont know which to follow.
Thanks guys!
 
The stock buick system is waste spark ignition system. This means the coil will fire both plugs at the same time of the same coil, one on compression and the other on the exhaust stroke.
As long as the wires are swithced to the corresponding cylinders, there should not be an issue.

Example;
Say one of the 3 coils has corresponding numbers 1-4.
Wires go from no #1 tower to cylinder 1, and tower 4 to #4 cylinder.
If you swap those wires around, it sould still be ok.

It sounds weird, but the system works very well.
Now, if the power wires under the coil are incorrectly hooked up there will be issues.
Hope this helps. :wink:

Are you runnng the stock HA or IC module?
 
HA IC? Im not sure what that even means! lol...I just bought the car a few weeks ago as a restore project. I dont know much about them YET! I will soon though! Anyway, I get what you mean by the coil pack thing, I think. What you are saying is, looking at the coil from the front of the car, If I swap the front 3 wires to the back and the back three wires to the front, I should have no problem as long as they stay in the order they are in. Is that correct? If I take the coli pack off the ignition module how do I know which wire goes to where? Thats the next thing I want to check.
Thanks for all your help!

Bill
 
I believe its the stock hot air module. I dont know if theres been upgrades or not. Any way to tell? I had the compter out of the car and its just hanging there right now so if I have to look at it that wouldnt be a problem.
 
If your car is a 84 GN it should have a ECM with service number# 1226459 on a paper tag on the side of the metal case...
 
the stock coil should say computer controlled coil ignition across the top of it- the 86-7 coil has nothing and is physically smaller in size... 84-5 (has 4 base bolts) on left 86-7 (has 3 base bolts and requires adapter to fit HA cars) on right in picture below...

stock-87 coil pics 004.jpg
 
Mine is a 85 module probably the same as the 84 but definitely different then the 86-87..I can see the difference in size. I am in the process of getting a new module and cap for a 86-87...Can I install this without any major changes...I know there is a adapter plate I have to use to mount it but anything else? If not I will pop that in and work on the whole hot wire kit and 86-87 mods after I get the car running right
 
The GM module should have numbers molded in it at the base.

Driver's side of engine, starting at the front=1, 3, 5
Passenger side from front= 2, 4, 6

Just match the numbers molded into the module to the correct plugs.
 
Mine is a 85 module probably the same as the 84 but definitely different then the 86-87..I can see the difference in size. I am in the process of getting a new module and cap for a 86-87...Can I install this without any major changes...I know there is a adapter plate I have to use to mount it but anything else? If not I will pop that in and work on the whole hot wire kit and 86-87 mods after I get the car running right

The 84/85 electrical wiring is different than 86/87.

More on swapping them HERE

Or use THIS harness from Caspers Electronics
 
Just figured I'd let you know that I won that book on ebay. I also went to NAPA yesterday to look around. I see alot of guys on here buy stuff from there. They didnt have much in stock but they sure have a great full color book of about 900 pages on performance parts and accessories. If you dont already have it check it out! Its $7.00 but worth it I think..

Thanks again for all your help!
 
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