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5th gen "coil on plug" setup.


Ranger77

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I know but they might have different dwell times as you stated.

The dwell time is controlled by the ECU, it basically grounds the coil for a certain amount of time. The lower resistance coils, like the CBR coils, require less dwell than the higher resistance coil. I believe this is where the problems arise. If you have too much dwell with a low resistance coil, you could eventually damage it or the CDI/TCI/ECU. If you ran a high resistance coil with a short dwell, then you won't charge the coil long enough to get a powerful spark.

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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:

3acb9f24642.gif

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!

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100V is the minimum. The GSXR manual says: 80V and more. I'm wondering if these coils might not be strong enough? I would think so. Would you need a stronger spark with an low compression or high compression engine?

Edited by Ranger77
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100V is the minimum. The GSXR manual says: 80V and more. I'm wondering if these coils might not be strong enough? I would think so. Would you need a stronger spark with an low compression or high compression engine?

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.

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It would be interesting to see what the spec is on the 6th gen coils. I have a feeling they have built in ignitors judging by the extra wire.

They do! They're one of very few 3-wire coils that seem to be out there in use on bikes. Not sure what the VFR1200 uses.

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I just realized, that I may actually have a set of CBR600F4i sticks in the bottom of my magical bin of wiring harnesses and electrical supplies... I'll dig around in there when I get home. If I find them, I'll measure the resistance and post up!

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Got some riding vids. Their shakey since all I have is RAM mounts.

She road better today. Felt pretty much normal with the coil sticks.

Edited by Ranger77
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I just realized, that I may actually have a set of CBR600F4i sticks in the bottom of my magical bin of wiring harnesses and electrical supplies... I'll dig around in there when I get home. If I find them, I'll measure the resistance and post up!

Interested...... :lurk:

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The best was on my way home. I was stopped at an intersection then took off slow when the light turned green. I held the throttle steady but fumbled and the rpms dropped some. I romped on the throttle and my rear just spun threw the intersection until I let off the throttle. These are rare occasions and I get gitty when they happen. The great thing is the rear never fish tails.

There's not a dyno even close to me so I use the "feel" dyno.

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She rode better today. Felt pretty much normal with the coil sticks.

I suppose this means the Viffer has a closed loop ignition dwell system then. Keep us posted.

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Well, I'm running Raid 0 on my desktop and I think one of my harddrives just took a dump so my time is going to be switched. Yea! Happy birthday to me.

You didn't RAID-0 your OS drive did you? Naughty!!

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Hey rangerscott, what are the chances of finding someone in your area that could do a current test using a low amp current probe and an oscilloscope on your primary coil wires?

If you could run that test, we could confirm if the coils are being saturated or if they're working OK. 7 amps of current with a nice clean "ramp" on the waveform is what we'd be looking for.

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She rode better today. Felt pretty much normal with the coil sticks.

I suppose this means the Viffer has a closed loop ignition dwell system then. Keep us posted.

Which would mean that 2 wire 1.6 ohm sticks will work fine? :unsure:

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I suppose this means the Viffer has a closed loop ignition dwell system then. Keep us posted.

Which would mean that 2 wire 1.6 ohm sticks will work fine? :unsure:

Yeah, it should mean that, if I'm anywhere near right. Which, I'm also :unsure: about. We either wait to see what happens with ranger's bike after a few weeks, or he manages to hook up a current clamp to one of the coils with an oscilloscope and we look for a good or bad waveform. All the material I can find points to a reading of 7 amps with a good waveform meaning it's all A-OK.

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Hey rangerscott, what are the chances of finding someone in your area that could do a current test using a low amp current probe and an oscilloscope on your primary coil wires?

If you could run that test, we could confirm if the coils are being saturated or if they're working OK. 7 amps of current with a nice clean "ramp" on the waveform is what we'd be looking for.

Ehhhh.......not sure. What type of business would most likely be using them?

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Hey rangerscott, what are the chances of finding someone in your area that could do a current test using a low amp current probe and an oscilloscope on your primary coil wires?

If you could run that test, we could confirm if the coils are being saturated or if they're working OK. 7 amps of current with a nice clean "ramp" on the waveform is what we'd be looking for.

Ehhhh.......not sure. What type of business would most likely be using them?

Your best bet is a good automotive diagnostic shop. We have a Bosch MTS 5200 lab scope at the shop where I work, complete with a low current clamp, and a bunch of other interesting test adapters(even a pressure transducer for testing running engine compression!). There has to be someone in your area that does a lot of automotive driveability and electrical diagnostics.

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Just a thought here, mostly directed to rangerscott69

Did you change the spark plug gap at all?

the lower resistance in the primary winding of the COP will increase the potential high voltage in the secondary coil.

If you don't open up the spark plug gap, your going to get a long yellowish buzzing spark, which you don't want.

You want to open up that gap a few thousands (I'd try steps of .002"), to get that spark back to a nice bright blue white arc that "snaps".

I see it all the time with the younger guys in my car clubs.

The get new heavy duty COP's with low resistance primary windings and then complain that their rides are sluggish.

The ford/lincoln guys particularly seem to suffer from this as OEM ford COP's are crap.

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