Wasted Spark Alternative

[AYW550]

i did a search on this already, but want to know more recently, has anyone tried any or the wasted spark alternatives out there? results?

[MissR34]

may i ask why you are considering this method?

[MissR34]

Distributorless ignition systems (DIS) have been around for almost a decade now, and have eliminated much of the maintenance that used to be associated with the ignition system. No distributor means there is no distributor cap or rotor to replace, and no troublesome vacuum or mechanical advance mechanisms to cause timing problems. Consequently, DIS ignition systems are pretty reliable.

Even so, that does not mean they are trouble-free. Failures can and do occur for a variety of reasons. So knowing how to identify and diagnose common DIS problems can save you a lot of guesswork the next time you encounter an engine that cranks but refuses to start, or one that runs but is missing or misfiring on one or more cylinders.

If an engine cranks but will not start, is it fuel, ignition or compression? Ignition is usually the easiest of the three to check because on most engines, all you have to do is pull off a plug wire and check for spark when the engine is cranked. On coil-over-plug DIS systems, there are no plug wires so you have to remove a coil and use a plug wire or adapter to check for a spark.

If there is no spark in one cylinder, try another. No spark in any cylinder would most likely indicate a failed DIS module or crankshaft position (CKP) sensor. Many engines that are equipped with electronic fuel injection also use the crankshaft position sensor signal to trigger the fuel injectors. So, if there is no spark and no injector activity, the problem is likely in the crank position sensor. No spark in only one cylinder or two cylinders that share a coil would tell you a coil has probably failed.

DIS COIL CHECKS

The coils in DIS ignition systems function the same as those in ordinary ignition systems, so testing is essentially the same. But the driveability symptoms caused by a weak coil or dead coil will be limited to one or two cylinders rather than all the cylinders. Many DIS systems use the "waste spark" setup where one coil fires a pair of spark plugs that are opposite one another in the firing order. Others, including the newer coil-over-plug systems, have a separate coil for each spark plug.

Individual DIS coils are tested in essentially the same way as epoxy-filled (square-type) ignition coils. First, isolate the coil pack by disconnecting all the leads. Set the ohmmeter in the low range, and recalibrate if necessary. Connect the ohmmeter leads across the ignition coil primary terminals, and compare the primary resistance reading to specifications (typically less than 2 ohms). Then connect the ohmmeter leads across the coil secondary terminals and compare the secondary resistance reading to specifications (typically 6,000-30,000 ohms). If readings are outside the specified range, the coil is defective and needs to be replaced.

If measuring the secondary resistance of a DIS coil is difficult because of the coils location, try removing the wires from the spark plugs and measure secondary resistance through the plug wires rather than at the secondary terminals on the coils. Just remember to add in a maximum of 8,000 ohms of resistance per foot for the plug wires.

DIS MODULE & SENSOR CHECKS

Here is a little trick that will literally show you if a DIS module and its crankshaft sensor circuit are working: connect a halogen headlamp to the spade terminals that mate the DIS module to the coils. A headlamp is recommended here because it puts more of a load on the module than a test lamp. If the headlamp flashes when the engine is cranked, the DIS module and crankshaft position sensor circuit are functioning. Therefore, the problem is in the coils.

If the headlamp does not flash, or there is no voltage to the module or coil pack when the engine is cranked, the problem is most likely in the crankshaft sensor circuit. On most vehicles, a bad crank position sensor will usually set a fault code, so use a scan tool to check for a code. Or, check the crank sensor itself.

Magnetic crank sensors can be tested by unplugging the electrical connector and checking resistance between the appropriate terminals. If resistance is not within specs, the sensor is bad and needs to be replaced.

Magnetic crank position sensors produce an alternating current when the engine is cranked so a voltage output check is another test that can be performed. With the sensor connected, read the output voltage across the appropriate module terminals while cranking the engine. If you see at least 20 mV on the AC scale, the sensor is good, meaning the fault is probably in the module. If the output voltage is low, remove the sensor and inspect the end of it for rust or debris (magnetic sensors will attract iron and steel particles). Clean the sensor, reinstall it and test again. Make sure it has the proper air gap (if adjustable) because the spacing between the end of the sensor and the reluctor wheel or notches in the crankshaft will affect sensor output voltage. If the air gap is correct and output is still low, replace the sensor.

Hall effect crankshaft position sensors typically have three terminals; one for current feed, one for ground and one for the output signal. The sensor must have voltage and ground to produce a signal, so check these terminals first with an analog voltmeter. Sensor output can be checked by unplugging the DIS module and cranking the engine to see if the sensor produces a voltage signal. The voltmeter needle should jump each time a shutter blade passes through the Hall effect switch. If observed on an oscilloscope, you should see a square waveform. No signal would tell you the sensor has failed.

DIS PERFORMANCE PROBLEMS

In instances where the engine starts and runs but does not perform well (lack of power, poor fuel economy, spark knock, elevated emissions, etc.), the problem may be outside the DIS system. First, the individual coils should be tested to make sure their primary and secondary resistance is within specs. If the coils are all okay, the electronic spark control circuit may be receiving bad information from another sensor.

Low MAP sensor output voltage or a coolant sensor that reads cold all the time will allow more spark advance than normal. This, in turn, may cause detonation (spark knock) problems when the engine is under load. So too can a faulty knock sensor or an EGR valve that is not working.

High MAP output voltage or a misadjusted throttle position sensor can have the opposite effect and cause the spark control system to retard timing more than normal. Retarded timing will reduce performance and fuel economy.

Do not forget, too, that ordinary secondary ignition problems can also cause misfires with DIS the same as a conventional ignition system. A bad spark plug wire or a worn or fouled spark plug will act just like a weak or bad DIS coil. So anytime you find an ignition problem that is isolated to a single cylinder, remove and inspect the spark plug and plug wire to rule out those possibilities.

[bozodos]

again in my own words, instead of copypasta from elsewhere:

I assume you're talking about using either Falcon or Commodore coilpacks and leads instead of the OEM type ones which sit directly on the plugs. From what I've read the two advantages of this are: less heat and its a lot cheaper than shelling out $500+ for coilpacks. I wouldn't bother.

Wasted spark is where there spark is fired in pairs so in one of the cylinders it is being fired on the exhaust stroke, thus being a 'wasted' spark. My Microtech LT10S uses this as it only has 4 outputs, not 6 as in the LTX12 .

[mad082]

wow, cara is really good at copying and pasting stuff isnt she...... and i don't really see how what she posted is even relevant. it doesn't even seem to mention wasted spark systems. so not to be rude cara, but please read what you are copy/pasting before doing so.

this is a "wasted spark for dummies"

the first thing you need to know is what '4 stroke' means when talking about engines, and what each stroke is called. this means that the piston has moved 4 different times between each spark. first there is the intake stroke. this is when the piston is moving down and the intake valves open to allow air and fuel into the cylinder chamber. then you have the compression stroke. the valves shut and the piston moves up to compress the air/fuel mixture read for the bang. the spark happens just before the piston gets to the top. then as the fuel is ignited and burns and expands you have the power stroke as the piston is forced down. this is followed by the final stroke called the exhaust stroke. this is when the piston is moving up pushing the burnt fuel out the exhaust valves into the exhaust system. and because of this 720 degree combusion process nearly every engine with an even number of cylinders will have a piston at the exact same point in the chamber moving in the same direction, but 360 degrees apart.

now that you know that, onto wasted spark.

wasted spark is when you run 3 coils instead of 6. each coil fires 2 cylinders at the same time. the cylinders at paired so that when 1 cylinder is firing on the compression stroke (when it normally fires), the other cylinder is firing on the exhaust stroke. since pretty much all the burnt and unburnt (if there is any) fuel has already been pushed out of the chamber and no fresh air/fuel has entered the chamber yet there is no power gained from this or damage done. it is the equivilant of turning on a light switch that turns on 2 lights but with no light bulb in one of the sockets.

[AYW550]

thanks for the replys guys, i understand how the wasted spark system works, but wanted to know results,,, turns out however that i wont be persuing that route anyways

turns out i would need to supply the guy who makes the wasted spark system with an ignitor from and older model RB motor in order for him to wire it up, cos apparently NEO motors have an ignitor on each coil or something like that,

but now that ive got my coils and plugs out.... my coils look perfectly new, i now suspect my problem is being caused by the spark plugs which have done almost 120,000 km.... pls see my other post "coil update"

[AYW550]

may i ask why you are considering this method?

was consdering this method cos i thought i had some coils that were stuffed and its way cheaper, but now that i got them out they look to be in mint condition, ive examined them VERY closely and cant find any cracks......unless eomthing could have happened to damaged the wrapping of the coils inside the coil? ....im also in NZ, so i dont think my coils get nearly as hot under the hood and your coils in auzzie would ...pls see my new post "coil update"

Edited August 10, 2009 by AYW550

[BoyWhoCriedWolf]

Cara, POST TITS OR GTFO!

[scathing]

Wow, someone can read a brochure.

I'd better street race her so I can get a trip to Japan and learn to dreeeeaft.

[bozodos]

she'll probably just try and sell you a MoTec exhaust though

[BoyWhoCriedWolf]

If you are getting wasted spark install a catch can, you can use it later sort of like the KERS systems on F1 cars.

[mad082]

If you are getting wasted spark install a catch can, you can use it later sort of like the KERS systems on F1 cars.

bahahahahaha

[SL33K]

***THREAD HIJACK***

i just read what wasted spark is above and understand what happens but i am failing to understand the reason why it is done?

what are teh benefits of a wasted spark setup?

[scathing]

i just read what wasted spark is above and understand what happens but i am failing to understand the reason why it is done?

what are teh benefits of a wasted spark setup?

Lets have a squiz, and try and put 2 and 2 together.

Wasted spark is where there spark is fired in pairs so in one of the cylinders it is being fired on the exhaust stroke, thus being a 'wasted' spark. My Microtech LT10S uses this as it only has 4 outputs, not 6 as in the LTX12 .

wasted spark is when you run 3 coils instead of 6. each coil fires 2 cylinders at the same time

It sounds like a method of reducing cost and complexity to me.

Fewer coils = fewer parts (for mad082's quote). It also lets you run a lower spec ECU (in bozodos' case).

[mad082]

in the case of skylines it is the fact that you can get coils of another car for little money and hook them up to work, which also gives a few advantages, such as they can be located in a part of the engine bay that isn't as hot, and then when they do happen to stuff up again they are very cheap to replace, even with brand new ones.

[bozodos]

mind you I didn't fit the godawful Microtech to mine, but yeah that model was designed with 4cyl in mind but can be run on an RB with wasted spark.

[BoyWhoCriedWolf]

KERS kunts, thats where its at

[SL33K]

Lets have a squiz, and try and put 2 and 2 together.

It sounds like a method of reducing cost and complexity to me.

Fewer coils = fewer parts (for mad082's quote). It also lets you run a lower spec ECU (in bozodos' case).

Thanks mate.

[BoyWhoCriedWolf]

No worries Vish brah, happy to help.

[STLKHR]

No worries Vish brah, happy to help.

First off leave Cara the f alone!

I have just converted my ignition to wasted spark, its a shit load better, i did not use some old crummy R32 ignitor either i made my own, pcb, components the lot! i had to cut the end of my loom and wire it into my new setup so it was just plug in and play and i used a VS coilpack...

Only issue i have is i have not figured out how to send the feedback loop to the ECU which means that the engine fault light stays up. anyone know how to fix this????