Define the waste spark system

[maybe2fast]

I was just wondering what the waste spark system does on our cars? I just was wondering if there was a benifit to it.

[topless94style]

Not exactly, when the coil discharges or sends spark to the plugs to fire the mixture, another cylinder gets a spark at the same time that does nothing.

[maybe2fast]

hence the two prong coil

[DaveFromColorado]

actually...

 

the way the wasted spart system works is let's just say you have a 2 cyl engine (just to simplify things)

 

Cyl 1 is on it's compression stroke, the coil fires a positive charge, the charge passes thru the wire and into cyl 2 on it's exhaust stroke from the center electrode to the ground electrode (getting rid of some of the extra unburned fuel and cleaning the emissions) the energy then passes thru the block and jumps the gap on the sparkplug on cyl 1 from the ground electrode to the center electrode burning the mixture in that cylinder.

 

it works almost backwards from what you'd think it should be doing.

 

--Dave.

[maybe2fast]

strang....

[solid_raiden223]

Now... Why does it do this?

[GnatGoSplat]

Now... Why does it do this?

 

TO SAVE MONEY!

It's cheaper to run 2 plugs off one coil than 1 plug off 1 coil. It also takes up less space. It also requires half the driver transistors in the ignition module, and is a lot less complex.

 

Technology has improved to where they can make real small coils now, so these days engines get Coil On Plug for DOHC, or Coil Near Plug for pushrod engines. That's where there is a small coil for each plug. COP ignition has coils directly mounted on the spark plugs (no plug wires at all) while CNP has the coil mounted usually on the valve cover with a real short (3-4") plug wire going to the plug.

[Canada]

Dave....did you write the books I have from school? Thats like a textbook definition.

 

Cost....and it works well for emissions. You make a part that can save 1 cent per car, and you build 1 million cars using that part.....thats $10,000 saved.

 

I'm not exactly sure if they are still firing the plug on the exhaust stroke on the COP/CNP ignition systems.....does anyone on here???

 

A thing to remember about watse spark and DynoJet (as well as anything else that is trying to read spark for rpm)......you place a pickup around the #1 wire and a computer running the dyno is able to see when that plug is fired and bases that for rpm.

 

This is why a lot of the DIS cars typically don't show a torque curve and are always horsepower vs mph.

[DaveFromColorado]

I do believe the F-body cars still fire the plug on the exhaust stroke.. not 100% sure tho.

 

I know more then I ever wanted to about ignition systems, as it's what I specialized in when I was going to school, that and drivability, two of the most worthless things I ever learned, as I don't use them at my job ... my job is mostly ball joint replacements on explorers, expeditions, blazers/jimmy's and of course, you can't forget all the 3.1/3.4 (pushrod) intake manifold gaskets.

 

--Dave.

[GnatGoSplat]

I'm not exactly sure if they are still firing the plug on the exhaust stroke on the COP/CNP ignition systems.....does anyone on here???

 

No, they don't need to. It works similar to the SFI system using crank and cam sensors to fire each plug independently.

[Canada]

I understand they don't NEED to.....but do they WANT to.

 

Dave....where did you go to school again? And where do you work again?

 

4.3 Blazers are VERY good money. Intake gaskets, valve cover gaskets, timing covers gasket, PS front pump seal, ball joints....all pay well and are fairly easy to do.

 

On 3400 U vans (Venture) do you take off the rear valve cover? You might want to try this......leave the coil packs and alternator on there (they are a BITCH)....take the bolts out of the lower intake normally and just pick the front up and walk it out. Matco makes a nice long ratching 10 mm wrench for accessing the rocker arms, its tight, but it works...and saves big time. Just be sure to squirt some GMS in the covers of the valve cover and be sure you don't roll the valve cover gasket when setting the intake back down. Sure, you aren't replacing the rear valve cover gasket......but its not like they leak anyways.

 

Also......I hate messing with the TB coolant lines......so I unhook the heater core hose as it meets that pipe and unbolt the water pump bolt and pull the upper intake and pipe off in one unit.

[DaveFromColorado]

I went to school at Eden Prairie Hennepin Tech. for my AAS, which I haven't completed yet (because of all my general classes) I work for a Tires Plus out here in Chaska, but I won't be working there much longer, soon I'll be working for the management company that own's the area that I live in - it's more money, and better use of my other skills for now (but I'll still be doing LOTS of side-work with all the specialized tools that I already have for drivability and ignition/electrical problems)

 

I haven't done any of the U vans. mostly the beretta/corsica's and w-boddied cars, and at least 2 N body cars (both grand am's) I hate* workin' on the 660's anymore, workin' at that job killed all* my fun in it, altho I'm the only one who has the tools to do the timing belts on the 3.4 DOHC engines (and yet I still have to replace my own timing belt)

 

--Dave.

[Canada]

The right tools, and the LQ1 is VERY good money.

[GnatGoSplat]

I understand they don't NEED to.....but do they WANT to.

 

Nope, it doesn't.

Eight ignition coils/modules are individually mounted above each cylinder on the rocker covers. The coils/modules are fired sequentially. There is an Ignition Control (IC) circuit for each ignition coil/module. The eight ignition control circuits are connected to the PCM. The PCM triggers each ignition coil/module individually and makes all timing decisions. The ignition coil/modules are supplied with the following circuits:

 

Ignition feed circuit

Ignition control circuit

Ground circuit

Reference low circuit

The ignition feed circuits are fused separately for each bank of the engine. The two fuses also supply the power for the injectors for that bank of the engine. Each coil/module is serviced separately.

 

This system puts out very high ignition energy for plug firing. Less energy is lost to ignition wire resistance because the ignition wires are shorter. Since the firing is sequential, each coil has seven events to saturate as opposed to the three in a waste spark arrangement. Futhermore, no energy is lost to the resistance of a waste spark system.