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Official LH2.4 EZK Wasted Spark Conversion - Installation Instructions

Think series circuit:

block -> spark a -> coil -> spark b -> block

The current flow does not alternate... spark plug a is always ground to tip and spark b is always tip to ground.
 
but think about installing a wasted spark system on a Volvo redblock engine. We are using wasted spark.....

GM used wasted spark for years...I still own two vehicles with wasted spark.

Repair Guide - GM Cavalier/Sunbird/Skyhawk/Firenza 1982-1994

The Direct Ignition System (DIS) or Electronic Ignition (EI) is used on the 1987-92 2.0L (VIN 1 and H), 2.2L (VIN G and 4), and all 1987 and later 2.8L (VIN W) and 3.1L (VIN T) engines.

The DIS or EI system does not use the conventional distributor and ignition coil. The system consists of two (4-cylinder) or 3 (6-cylinder) separate ignition coils, an ignition module, DIS ignition module or Ignition Control Module (ICM) as applicable, crankshaft sensor or combination sensor, along with the related connecting wires and Electronic Spark Timing (EST) or Ignition Control (IC) portion of the computer control module (ECM/PCM).

The distributorless system uses a "waste spark" method of spark distribution. Companion cylinders are paired and the spark occurs simultaneously in the cylinder with the piston coming up on the compression stroke and in the companion cylinder with the piston coming up on the exhaust stroke.
 
The polarity of the current never changes for a given pair of spark plugs. One of the plugs in the pair will always have current flowing in the opposite direction of the other.

Here's a random diagram I found on google that illustrates the point: http://1.bp.blogspot.com/-joUcEDP1M...AAAHc/PXz7YCyWXvY/s1600/WasteSparkDiagram.jpg

The circuit for the secondary winding is being completed through the block and the current always flows in the same direction, which means one plug sees opposite current polarity of the other plug.

I have admittedly never given this much thought. If it means the plugs only last X miles instead of Y miles (where X is some 5 digit number) then I'm personally not bothered by it. It's a fair point though, and people should decide for themselves if it's worth getting special spark plugs.
 
With each pair of plugs running wasted spark, the spark on one plug always jumps normally and the spark on the other plug jumps in the opposite direction. For instance, in the 1-4 pair, #1 will always jump normally center to outer electrode, and #4 will always jump backwards outer to center electrode. The path of each spark will be the closest point between center and outer electrodes.

If you can find diagrams that show the internal wiring of an old fashioned single coil (used with a distributor), you'll see that one end of the primary and secondary windings is connected together. This is the return path for the spark energy. With a wasted spark coil pack, the two ends of the secondary winding are connected only to the spark plugs -- the coil gets charged up, the primary is disconnected, and the collapsing magnetic field generates the spark voltage across the secondary. To discharge, a spark needs to simultaneously form on both ends of the coil to complete the electrical path.

I've read the claims that special plugs are needed for wasted spark but I don't get it. Platinum plugs have a shortened center-to-outer electrode path such that the spark is always on the platinum. This allows the plugs to last for 100K miles. If you're going to inspect and change your plugs more frequently, standard copper plugs are fine for wasted spark. (I guess the sharpened electrodes on a platinum plug might be a bit better if you're fowling plugs.)
 
Ok guys, sorry I misunderstood and thought that the argument was that the polarity was somehow being switched to alternately fire cylinder 1 & 4 as pos/neg then neg/pos, for example, within that circuit.

I understand that wasn't the claim now and I think we're all on the same page. The coil secondary circuits are grounded back to the opposite side of the same pair of coils.

Carry on...

IW8simF.gif
 
it means the plugs only last X miles instead of Y miles....

Bingo,...platinum discs exist on both sides, ground and the center electrode, to last a long time.

On GM wasted spark engines, those plugs last a long time...I have no idea if there is a cross-reference to work on redblocks converted to wasted spark setups.
 
price went up. are therr any differences between these and the first run form back in the day?

In group buy form these were $50 each, but Karl sold them individually for $65. I had to raise the price by $2 to $67 each to cover the costs of running a web store. But the upsides are that transactions are quick and easy, and shipping is included, with a tracking number.

This batch of boards is different from the first run, but I don't have all the details. I'll ask Karl to fill you in.

Thanks,
Chris
 
Got my board within 3 days for $2 shipping. I have it all soldered onto the ezk board. Gonna try to use a newer (06 07?) Subaru coil with module built into it. Its a four wire coil. Power, ground, 1+4, 3+2. Anybody have any experience with this? Or another 4 wire coil?
 
Some quick questions...Got my board about a month ago,had Shane solder it up for me and wired it up last night using his diagram. Using a goldbox EZK.

Using LS coils.

---Just pops and cranks like its out of time.

A couple things.
--I sourced 12V from the factory coil power source -- Is that ok?
--I grounded both grounds to the firewall(B and A) signal ground and ground. Am i missing something here? Should one of those grounds come from the factory powerstage?

Do i keep the factory powerstage?

This is the diagram i used...



Thanks for the help,very excited here...Look how nice she looks :)
 
Using LS coils

When I searched this topic out, several years ago, my understanding then was "dwell time" might be an issue since 8 cylinders have a longer "wait" time before coil is charged (dwell time).

Myself, I would find LS coil specs, and do the dwell-timing arithmetic. IIRC, for a 4 cylinder with wasted spark, one might exceed GM's timing-envelope specification with higher RPMs.
 

Sidebar - LS2 Truck Coils

I recently reviewed a 2015 forum thread about coil's dwell time, and then examined two different LS dwell tables here ( factory dwell table for an LQ9), and here (2004 Silverado 5.3 dwell table), from this forum.

Based upon B230F NA LH 2.4 test I did back then, which I plan to recheck with another automotive DVOM in next several weeks, I found an OEM single coil's dwell time range of 6 ms to 3.5 ms (idle RPM to higher RPM).

Vagman posted (May 15, 2013) in that Megasquirt Support Forum that "BTW apparently there are people who "boosted" these coils with up to 6+ms without any spark scatter issues."

As such, if Vagman's statement is true, and NA LH 2.4 idle dwell of 6 ms is true, then these LS2 (D585) coils should not have an issue with wasted spark setup. I would have to see a LH coil dwell table if one was available, but as the RPMs increase, Bosch's LH coil dwell time may be quite similar to GM's dwells.

Duty Cycle wise, a 4 cylinder wasted spark is higher than a 8 cylinder, but duty cycle is more relevant at sustained higher RPMs.

If one wanted to be conservative, the power feed going to these LS2 coils could be dropped down a volt by using a resistor.
 
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