kaldek

Stronger, if I recall correctly. Something to do with high compression making it harder to ignite the mixture. I don't think your coils are a problem at all. The more I look into this, the more it seems to confirm that the problem is just going to turn out to be an incompatibility between the 5th-gen ECU and the newer coils due to the required dwell time.

Wow. I was trying to do some peak voltage tests using my oscilloscope and just couldn't get a reading lower than 268 volts when it should apparently be 100 volts. I'm thinking WTF, but then I find out that my oscilloscope is more sensitive than the equipment generally used for peak voltage testing. So, why am I getting such a weird result? Apparently, when the secondary coil magnetic field collapses, it generates a "high voltage flyback" pulse into the primary coil that lasts not longer than ten microseconds (not milliseconds - MICRO seconds). At the 1 million samples-per-second rate of my oscilloscope, I'm way faster than your average peak voltage detector at 1 million samples per second but I've seen evidence it loses the plot after about 150,000 and starts to alias the signal. That explains why I don't see the true peak which is somewhere around 400 volts. I'm seeing 268 volts, and a peak voltage tester would only see 100 volts because it can't sample fast enough to see the initial burst at all, instead measuring a peak of 100 volts because that's all it can see at its level of accuracy. Check out how fast this pulse is: You can see where that pulse narrows is where my oscilloscope loses its marbles and can't see that tiny 400 volt sliver. This graph was taken by a professional grade peak voltage tester somewhere above 20 million samples per second. Dayum!

CBR coils are also 1.6 ohm.

Cool. About the only thing we haven't discussed is the dwell time for the coils, and whether the ones you're using work best with a much different dwell time than what the ECU is providing. Less resistance would affect dwell time I guess. Maybe it's too much and you're overcharging the coils? Again, I could be talking out my rear-end here. Watching the oscilloscope, you can see that power is rapidly switched on and off to the coil. The time that the coil spends "on" is the dwell time and if it's too short the coil won't charge up enough. Too long and it builds up too much. Here's a great article on dwell time calibration. In short, they appear to say you can't just dump any coil on and hope for the best. They say on that page that if the dwell map is pre-computed at the factory and does not measure the amps, then you're going to cook something in short order. NEVER substitute the coil for another type on a mapped system. The ECU will not know you have done this and will still turn the coil on for a certain time, if your new coil charges quicker (lower inductance) then the coil or ECU will be damaged. If a slower charging coil is fitted (higher inductance) you will get a poor spark. Alternatively, the ECU could be "closed loop" in that it monitors the coil current and dynamically adjusts the dwell time so that the coil tops out at 7 amps. I guess this means that your system on the VFR was always 7 amps, but used a longer dwell time to get there since the inductance/resistance was higher. So, if the 5th-gen VFR uses mapped dwell, you're hosed. If it uses closed-loop dwell control, apparently you should be alright.

And you're sure that's not caused by the 6th-gen throttle bodies yeah? I didn't see how long you had been riding around with the 6th-gen throttle assembly before trying the coils. As they say - change ONE thing, then test it. When you're 100% convinced it's working, then (and only then) change something else. Not that I listen to my own advice though; no, I'm as guilty of this as anyone.

Maybe describe the poor running problems again? You said it was sluggish?

If rangerscott is willing to buy one of the $60 pocket oscilloscopes like what I have, he could well do that. "Lab Scope" is an automotive term which generally means $$$$$. They're just oscilloscopes. It would probably also require a low amp current probe as the input to the oscilloscope, clamped over the coil wire for inductive pickup. I've just ordered one, and it's being shipped to Sebspeed's house right now.

I'm actually starting to think that these coils need to be given the power they want, rather than trying to affect it by adding resistors into the circuit. It's all my fault - it was a stupid idea to talk about resistors in the first place because I knew enough to be an ass and not much else. So I guess the last question then is whether the current pulled by each coil will affect the ECU. And if not, then Ranger's problems with the bike being sluggish are something else altogether and I need to STFU.

Duhh...yeah of course you're right. It's a GROUND trigger not a positive trigger. Man I've really got my "muppet" hat on at the moment.

Kostritzer is right. I just hooked up the oscilloscope to my CBR1000RR and confirmed that the coils are indeed getting a 12 volt feed. They are also most definitely 1.6 ohm coils. So, take everything I said about 6 volts and kick it in the nuts. The coils are 12 volts, so there is no danger of burning anything out. Since it's a ground trigger, it's also hard to say if there will be any problems with the coils pulling 7 amps rather than 3. At this point, it seems that I've been talking out of my ass.

If your existing coil resistances are 3.2 ohm, you'll need to find 3.2 ohm COP units unless we work out if a ballast resistor solution will work. Could this be as simple as splicing a 1.6 ohm resistor on the hot wire to the 1.6ohm COP? That's what I don't know yet. Right now I think I know enough to get into trouble. What I need to freakin' do is get out to my CBR, hook up the oscilloscope to a coil and confirm what the darn volts are. If it's 6 volt it will confirm what I've said so far and we can move on to talking about resistors.

That being said, I think I remember reading somewhere that the 5th gen had individual cylinder timing, maybe it was fuel trim...can't remember. Ignore this - read the posts further on. Wasted spark with two coils in series when the ECU expects there to be four individual coils could be ugly. You would need to have the two coils charged by two separate 12 volt feeds and fire whenever either of those feeds is cut. I'm sure this could be done with a fancy diode arrangement.. But at that point, aren't we getting very complex for the sake of not much in return?

Sometimes I'm just wrong consistently. Ignore everything below here. If your existing coil resistances are 3.2 ohm, you'll need to find 3.2 ohm COP units unless we work out if a ballast resistor solution will work.

OK, I've measured both of my bikes. The CBR1000RR has 1.6 ohm resistance on the primary windings (between the pins). The VFR appears to be unmeasurable due to the fact that it uses a transistor; the readings were either 50Kohms or 1Kohm.

Yeah 3.2 ohms. I'll test mine tonight on my CBR 1000RR (if I can get to it) and the VFR too. My oscilloscope will arrive today as well, so I can use that to tell you exactly how many volts they're getting. Wheeee!

Oh, please keep going! If I sounded negative today it was just so you didn't accidentally fry your electrics.

I'm SO WRONNNNNG. The ECU would be delivering 6 volts rather than 12 volts to them. Much like how the Throttle Position Sensor (TPS) and MAP sensor are given a 5 volt reference signal by the ECU. In the case of the TPS and MAP, the ECU would use linear voltage regulators, but in the case of the coils it's probably using ballast resistors (on bikes that use 6 volt coils).

No, added resistance before the load won't affect the load (the coil) aside from diminish how much voltage it's getting. The only thing I'm not sure about is the exact effect on this particular coil. All the stuff below? ALSO WRONG! Since you say that the source bike does not use a wasted spark system, I would say these are designed to operate with a ballast resistor to drop the source voltage from 12 volts down to 6, with a temporary bypass for a 12 volt kick during starting. If they are 6-volt coils (and I reckon they are), then right now you are: Burning out the CDI transistors The 12 volt CDI transistors are not rated to the 7 amps your new coils are asking of them. You're damaging them every time you run the engine. Burning out the coil The coil is designed to deliver ~30,000 volts based on a 6-volt primary field winding. You are doubling that. I don't know if this means you're generating 60,000 volts (probably not, but I'm not that awesome with the electrical theory). This may or may not be burning out the coil windings, much like how our stators tend to burn out from too much current and heat. Burning out the spark plug electrodes The higher spark voltage might consume the electrode material rapidly. My disclaimer is that I am not 100% sure about the last two points. I could be wrong about higher input voltage on the primary winding affecting voltage generated by the secondary winding.

The different coloured wires are the trigger wires; all others are in parallel on the same circuit as the coil is constant powered with the transistor in the coil head doing the switching.

Everything below here is wrong also! They're probably wired the same as a VFR800, but are likely 6 volt coils rather than 12 volt. Seriously I would stop right now before you blow up your ECU, and go do more research. Maybe ballast resistors is all you will need, I don't know.

He can't do that because that diagram is for a wasted spark system, and the VFR800 is not wasted spark.

EVERYTHING WRITTEN HERE IS WRONG!!! Move on, people. Ok here's an interesting quote regarding 1.6 ohm coils, found on some random forum: A coil that is intended to be used with a ballast resistor has approximately half the resistance of a non-ballast coil. The reason for using a coil and ballast set up is to give you a stronger spark at start up. The ballast coil is essentially a 6 volt coil and the ballast is there to give it a 6 volt supply in normal running. When you start the engine, the ballast is bypassed and the full 12 volts is applied to the coil giving roughly twice the output voltage. This helps cold starting. The fact that these are 6 volt coils is kinda what I was thinking, although I was thinking 5 volts rather than 6 (hey, I'm an IT guy and it's 12 and 5 volts inside PCs). So it looks like you've just chucked a ballast resistor-type coil onto a non-ballast ignition system. I'm not sure what the correct course of action is, but I'd wager that right now you are at risk of frying your ECU. Also, you're probably burning out the spark plug electrodes!

Verrry interesting. I'll check mine tonight but since they're 3-wire coils the results may not be comparable. It could be that these new coils are pulling so much current from the ECU that it is suffering a brownout. Your old coils pulled 3.7 amps each (since they are 3.2 ohms at 12 volts), the new ones pulls 7 amps each. Granted, these are "pulse" figures but that's a doubling of current. I've heard of people using ballast resistors to increase the resistance but then that might affect the spark, because each coil WANTS that 7 amps. More Googling required, methinks.

Across which pins? Beats me. The fsm doesnt state anything on ohms with the coils. On two prongs i just touch the two. No clue on the 3 prongs the 6th gens have. Im getting around 3.1 ohms on the 5th gens and 1.6 ohms on the gsxr's. Less resistance = more current. Are you concerned that the new coils are drawing more current than your ECU can provide?

Across which pins?