P5 1.8 coil swap project

[Kansei]

It was probably supposed to eliminiate the possibility of bad wires being as you're only using half as many now.

A wasted spark ignition system is only made to be a cost saving. Less plug wires = less cost. two coils instead of four, firing the spark plug twice as often as it needs to be because it means you can have two less coils = less money.

it's pretty much the simplest ignition system I can think of.. no moving parks like in a distributor/rotor setup, no 4 expensive coils to control, etc

 

[Maxx Mazda]

And it's actually just as effective. The only deficit being you need to change plugs twice as often. I'm surprised more manufacturers don't use it...

 

[Kansei]

And it's actually just as effective. The only deficit being you need to change plugs twice as often. I'm surprised more manufacturers don't use it...

maybe coil prices at a wholesale level are low enough that it's barely more expensive? Hell, with how cheap copper NGK plugs are at advance auto parts, I wouldn't mind needing to change them at the oil change interval haha (oh wait, I have been changing them every oil change, and my last three oil changes have been less than 1k miles for various reasons ).

I still wonder who came up with the idea haha.

 

[Maxx Mazda]

Does it not seem to you that wasted spark is actually a betteridea?

 

[Kansei]

Does it not seem to you that wasted spark is actually a betteridea?

better? than direct ignition? with direct ignition, if for some stupid reason you really wanted your plugs to wear twice as fast, you could program the ECU to fire on the same two strokes.

The extra spark does virtually nothing, hence the "wasted"

 

[Maxx Mazda]

Sorry, what I meant by better was i nthe simplicity of the system. In that respect it's far superior.

 

[njaremka]

all wasted spark ignition does is make sure ALL the fuel-air is burned. its all about emmissions.

AND, the 18 set-up is still wasted spark, its just got 4 wires instead of two. all you are doing in the conversion is relocating the coils.

 

[i12drivemyMP5]

Tell the car that. If that's all it does then it would run the same as before. It's noticeably smoother now. Longevity test in progress...............

 

[Kooldino]

From that link

It would have been nice if the dyno sheets all used the same X and Y scales. Unfortunately they didn't. Even so, the difference between the wires looks like experimental noise to me. For instance, the maxpower point cited is between 230 and 234 for all the wires,

Actually 229 to 234...

and the runs on the OEM wires covered that range all by themselves. That is, there's no evidence here that any of these worked better (or worse) than the others, at least in terms of dyno numbers. Given these graphs, how the OEM wires "outperformed" one of the other wires escapes me.

OEM parts are generally decent.

My point is though, that saying that "spark is spark" is oversimplifying things.

 

[Kansei]

all wasted spark ignition does is make sure ALL the fuel-air is burned. its all about emmissions.

AND, the 18 set-up is still wasted spark, its just got 4 wires instead of two. all you are doing in the conversion is relocating the coils.

from what I read (little wikipedia stub article on wasted spark ignition systems) the second spark does nothing.

and yeah I know the 1.8 coil pack setup is still the same wasted spark, I figure our ECU is only set up to drive the two "channels" of spark plugs.

An ignition system in a four-stroke cycle internal combustion engine may fire spark plugs in pairs, on both the exhaust and compression strokes. The extra spark on the exhaust stroke has no effect and is thus "wasted". This design is simpler than a conventional ignition system, but the extra sparks reduce the lifespan of components (contact breaker, spark plugs).

 

[Kooldino]

And it's actually just as effective. The only deficit being you need to change plugs twice as often. I'm surprised more manufacturers don't use it...

I think coils are getting cheap enough to where manufacturers just want to slap one on each cylinder.

 

[Kooldino]

Does it not seem to you that wasted spark is actually a betteridea?

Not really. Like you said, it will increase spark plug wear (probably not by twofold, but it would). And theoretically, it would allow for less dwell time, but I'm not sure how that comes into play in the real world.

 

[Kansei]

Not really. Like you said, it will increase spark plug wear (probably not by twofold, but it would). And theoretically, it would allow for less dwell time, but I'm not sure how that comes into play in the real world.

I think the wear is doubled, the wasted spark is just as strong as the needed spark.. granted there's no explosion the second time but I dunno what % of the wear is caused by the explosion vs just the spark.

 

[pasadena_commut]

but I dunno what % of the wear is caused by the explosion vs just the spark.

I suspect that it's mostly the spark. The spark combines very high heat, very reactive ionized gases, and large electric fields. That's pretty much the ideal formula for removing atoms from the surface of an electrode. I think the only reason spark plugs last as long as they do is that they spend most of their life without a spark. Hook one up for continuous discharge (if you happen to have a 10 kilovolt battery handy) and I bet it would burn out in no time.

On a related note - what happens to the metal that is vaporized off the spark plug electrodes? Does it make it all the way out of the tail pipe, or does it stick to the inside of the cylinder, or does it land somewhere in between? I know it's not a lot of material, but I don't recall seeing an EPA standard for it, and breathing metals, in any form, isn't usually a great idea.

 

[six_dolla_bill]

anyone do this setup and feel a dramatic difference in cutting down hesitation or "lag"? especially on take off to be specific

 

[i12drivemyMP5]

This coil swap, long reach plugs & VTCS removal together have all made a dramatic improvement in smooth & quiet idling & power delivery throughout the rpm range.

 

[Dave_x]

Ok, the pieces are in place. I have my wires, new plugs, valve cover, and I'll pick-up the coil pack from NAPA tonight. I hope to do the swap this weekend. I'm planning on taking some pics and tell how it went.

Any advice from those who have done the swap? How much of a pain is changing the wiring? Any tips/ideas/comments?

Thanks!

 

[njaremka]

moving the wiring harness isn't all that hard, just time consuming. make sure you don't snip through any wires when you are cutting the harness apart.

 

[Dave_x]

moving the wiring harness isn't all that hard, just time consuming. make sure you don't snip through any wires when you are cutting the harness apart.

I thought I read in one of the other threads about re-wrapping the harness with electrical tape. Is that the best means?

 

[Kansei]

Maybe some super duper electrical tape will be fine, but the cheap stuff doesn't hold up well to heat at all.. being that close to the engine it'll turn into goop in no time at all. I'd use a split loom over the wiring and then electrical tape the ends and the seam on that.. that way barely any residue can get on the actual wires.