A New Formula In Our Stall

[GTRS Fiero]

If so, what does the Duke do with the wasted pulse?

[Fierofool]

Steve, you're correct about the waste spark.  GM uses 1 coil for 2 cylinders on the DIS systems.  Melanie's Grand AM and Grand Prix was like that.  I remember the Grand Am had the cylinder numbers printed on the coil next to each terminal.  The ICM fired both cylinders on a coil at the same time, rather than separating them. 

They should only be interpreted as 1 pulse because that's the input. 

[GTRS Fiero]

On mine, the tach is sccurate, with the sinhle coil for 2 cylinders.

[TopNotch]

Today I flushed the cooling system on the 3800 car. After my test drive last weekend, the fresh coolant I had put in turned rust colored, so I figured I'd better flush it. Before that, I replaced the coolant overflow reservoir with one i had in the garage. The old one looked like this:

There was a lot of rusty sediment in the bottom. The "new" one looks like this:

It's not new, and has a bit of crud caked on the inside, but it's a lot better.
Here's the other overflow reservoir I put in the back:

There wasn't room in the engine bay for it, with that big 3800 in there. I also replaced the hood with the better one Fierofool had brought over a while back.

It looks a lot better now.
Now all I need is for the board of directors to decide how much to sell this thing to me for, because i'm bringing my checkbook to the next meeting.

[GTRS Fiero]

I'm not on the board, but I'd like to make several points:
1. TopNotch has done most of the work to get this Fiero to where it is now
2. Whatever monies have been spent out of his own pocket on this Fiero, no progress would have been made without TopNotch's efforts
3. Although I am not privy to the conditions under which this Fiero came to GFC, the Fiero needs to go to someone who wants it, and can get it back on the road.
4. It would fair that, if TopNotch wants to purchase this Fiero, he should have first shot at it
5. It would be reasonable for this Fiero to be sold to TopNotch priced for the condition it was in, prior to TopNotch's efforts
6. It would seem that the club needs to offload things, when it can

[Fierofool]

If so, what does the Duke do with the wasted pulse?

You never got an answer on this.  I think it works to help give a little cleaner exhaust.  I recall another vehicle that used that method.  I think it was a Nissan truck.  The 4 cylinder that had 8 spark plugs. 

[GTRS Fiero]

So, it ignites remaining fumes in the exhaust?  Of course, almost everything would have been pushed out of the cylinder, by then.

[Fierofool]

It would depend upon where in the stroke that cylinder was.  If it were at the bottom of the power stroke, it could burn residuals.  I don't know how the cylinders on an individual coil relate to each other in their cycles.  This is only my theory, so there's no real technical basis on my part. 

It could also be that this was the most efficient way rather than having an ICM that would fire 6 individual coils.  That has been overcome by the coil-on-plug systems where each cylinder has it's own coil. 

[GTRS Fiero]

I think it's just wasted, on mine.

[Fierofool]

The firing order of the 3800 is different from the Fiero.  The cylinders are numbered differently because it was front wheel drive.  The number 2 cylinder on the Fiero corresponds to the number 1 on the 3800.  The odd cylinder bank is at the back glass and the even cylinder bank is at the trunk.  Firing order runs 1-6-5-4-3-2. 

The coil packs combine 1-4, 5-2, and 3-6 on the Buick engine.  Autozone lists the order as 1-2, 5-4, 3-6.  All others list the former. 

[GTRS Fiero]

The 3800 is a 90-degree V6

[Fierofool]

The F series 3.4 has the same cylinders combined on a coil as the Buick 3800, though.  1-4, 5-2, and 3-6, however it does appear that the coils are placed in different sequence between the two engines. 

[Raydar]

If so, what does the Duke do with the wasted pulse?

Instead of firing just before the top of the compression stroke (as the other side of the coil pack is doing) it will fire just before the top of the exhaust stroke.
It may help to ignite any remaining fuel, as it leaves the cylinder. Or it may not. I'm thinking that most of the oxygen will have been depleted by that point, but it really doesn't matter. It doesn't contribute anything to the power output of the engine. I think that it was just a convenient way to configure the coil packs. 

[GTRS Fiero]

No oxygen or compression.

[MikeMac]

I'm not on the board, but I'd like to make several points:
1. TopNotch has done most of the work to get this Fiero to where it is now
2. Whatever monies have been spent out of his own pocket on this Fiero, no progress would have been made without TopNotch's efforts
3. Although I am not privy to the conditions under which this Fiero came to GFC, the Fiero needs to go to someone who wants it, and can get it back on the road.
4. It would fair that, if TopNotch wants to purchase this Fiero, he should have first shot at it
5. It would be reasonable for this Fiero to be sold to TopNotch priced for the condition it was in, prior to TopNotch's efforts
6. It would seem that the club needs to offload things, when it can

I agree with all of the above. Well put.