Possible Bad Coil Pack??

My bike is running great until it is up to full operating temp and then it just seems to drop a cylinder or two randomly.

All fuses are good, battery is good, oil and coolant are good, ground is good, wires and spark plugs are good, no codes, and everything test good in diag mode.

Theory is once the bike get up to temp one of the coil packs is failing. By the temp on the headers it seems to be 2 and 3. Moved wires and coil packs and then it moves to 1 and 4.

Coil packs test within specs cold, gona try to heat them up and retest them hot later on tonight or tommorow.

If its not the coil packs does anyone have any other ideas?

UHcougarJohn said:

My bike is running great until it is up to full operating temp and then it just seems to drop a cylinder or two randomly.

All fuses are good, battery is good, oil and coolant are good, ground is good, wires and spark plugs are good, no codes, and everything test good in diag mode.

Theory is once the bike get up to temp one of the coil packs is failing. By the temp on the headers it seems to be 2 and 3. Moved wires and coil packs and then it moves to 1 and 4.

Coil packs test within specs cold, gona try to heat them up and retest them hot later on tonight or tommorow.

If its not the coil packs does anyone have any other ideas?

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I've posted this many times so perhaps I can condense it into something short and sweet. If it starts and idles the Ohm reading by measuring the coils is nearly useless. Although its good to know its the break down voltage or the leakage energy that we need to know. I suspect you are on the right path if swapping wires moved the issue and it is the coils.
The problem is we don't have the proper tools to test the coils. What you need to know is if the coils secondary energy is making it to the spark plug. Right now its very likely its jumping through either the coil body, coil wires, or even the caps to ground. If I were you I'd get to the darkest place you can and unplug the head light and fire it up. If its missing you may be able to see the arc over from the wire to the frame or other grounded items.
The next option is to mist wires and coil with a spray bottle and see if it causes it to misfire. If it does, it sounds like you need to replace it!

do a search for my user name and coils, wire, mist, arc over, high voltage something like that and I'm sure you'll find other posts like this.

+1^^^^
The fact that you've swapped the coils and can see the cylinders also change is a pretty positive indicator that you're on the right track. The secondary voltages may be arcing over internally in the secondary coil. Or you may have an opening primary winding when the unit heats and expands.

UHcougarJohn said:

My bike is running great until it is up to full operating temp and then it just seems to drop a cylinder or two randomly....Theory is once the bike get up to temp one of the coil packs is failing. By the temp on the headers it seems to be 2 and 3. Moved wires and coil packs and then it moves to 1 and 4....

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Seems to me you have diagnosed the problem properly. The only thing left would be damaged wiring or connection from the ECU to the coil but that is VERY unlikely.

I would purchase a new/used coil.

Thanks all, I am going to order a new coil, and see if it fixes my issue.

The heat test didn't really give me any diffrent results.

I'm sure it will take close to a week to recieve the part, I'll let you know what happens.

UHcougarJohn said:

Thanks all, I am going to order a new coil, and see if it fixes my issue.

The heat test didn't really give me any diffrent results.

I'm sure it will take close to a week to recieve the part, I'll let you know what happens.

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If you have to ride it; you can always apply black electrical tape to the coil wires. If they're breaking down it will add an extra layer of insulation. You can tape the pack too if it arcing from the output to one of the inputs. Cleaning all dirt, oil, grime off them can help too. More than likely its an internal arc over that you can't do anything about (because its heat induced). So at the expense of roughed up knuckle and a roll of tape you can try!

FinalImpact said:

If you have to ride it; you can always apply black electrical tape to the coil wires. If they're breaking down it will add an extra layer of insulation. You can tape the pack too if it arcing from the output to one of the inputs. Cleaning all dirt, oil, grime off them can help too. More than likely its an internal arc over that you can't do anything about (because its heat induced). So at the expense of roughed up knuckle and a roll of tape you can try!

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Yeah I'm just gona park it till I get the coil pack. It doesn't sound good once it starts acting up.

UHcougarJohn said:

Yeah I'm just gona park it till I get the coil pack. It doesn't sound good once it starts acting up.

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Any update??? PS - your gonna need a long 3mm hex driver to get the air box off!

FinalImpact said:

Any update??? PS - your gonna need a long 3mm hex driver to get the air box off!

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I am still waiting for the part. I odered the part a week ago, I'm gona call them tommorow to check on it.

Hopefully I get the part soon, I hate Rollin around in my gas eating dodge ram. Also, I have a planned trip to Colorado the last week of August, so it has to work.

Ok I called RonAyers and the coil is shipping today

Any special tips I should know about swapping out the wires from the old coil to the new coil?

PS - The coils and wires are already out of the bike.

It seems you're way ahead of the game as you diagnosed it yourself, pulled it yourself and have stuff in mail so - not allot to add. While there you may give it some new plugs, check all the other electrical connections and make sure there is no fungus or corrosion inside them and maybe add some dialectic grease to all the connections. . . .

Try not to leave any greasy finger prints on the coils or wires as it attracts debris but that's about it. Have fun with that rubber shield under the air box! Lastly - let us know how it goes!

FinalImpact said:

It seems you're way ahead of the game as you diagnosed it yourself, pulled it yourself and have stuff in mail so - not allot to add. While there you may give it some new plugs, check all the other electrical connections and make sure there is no fungus or corrosion inside them and maybe add some dialectic grease to all the connections. . . .

Try not to leave any greasy finger prints on the coils or wires as it attracts debris but that's about it. Have fun with that rubber shield under the air box! Lastly - let us know how it goes!

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Thanks, and that rubber shield looks like its gona be the best part

Update, changed the coil pack and the bike was running even worse. We check everything in diag mode and ckecked all the sensors We could and everthing seems to be good.

So then we pulled the plugs and swapped them with the old ones I had on hand from when I last changed my plugs. 1,2,4 where wet and 3 seemed normal.

Put the bike back together fired it up and it ran great. So we where off for the test ride and as soon as the bike warmed up, pulled to a stop sign and it died. Same symtoms as before. Runs great till it gets up to temp and then it don't run worth a damn.

Is there a way besides diag mode to check the injectors? Also, is it possible to check the ECU?

It doesn't seem to be ignition but possibly its fuel.

Thanks, I'm going to sleep.

Late to chime in and electrical isn't my strongest point...

Do have access to a timing light (not used much more nowadays except on older cars)?

If you can slip the plug wire end of the tool over the FZ's plugs one at a time and watch the light (you can hook it up to another 12 volt battery to make things easier) when its running both cold and hot???

This would/should let you know for certain if your loosing spark AT TEMP, and which cylinders/coil packs as it won't be lighting up half as much as normal..

A thermal heat gun pointed at the header once hot would help pin point which cylinder is not firing but you still won't know if its lack of spark or the FI system...

One other thing, on the ends of the wires, where they go into the coil packs, were they fairly clean, NO ARCING/carbon?

That's too bad! :thumbdown:
If the plugs are wet implies in some faint way that fuel is present but no spark to burn that fuel off.

Is it fair to say that both the old and new plugs were subjected to the "potentialially bad coil pack?"

I hate to hint at the ECM as being bad but a thorough inspection of the wire harness between the coils and the ECM (you need to ohm them) and check the grounds. Unlikely but also the pick up coil. Any chance the timing chain had gotten to p/u coil??

Those are my first thoughts. . .

In the beginning the symptom seemed to get worse at higher engine temp. The coils were swapped and the condition existed and the miss changed to the opposite cylinders.

Does the bike run okay when cold? Is the ECU dumping lots of fuel because it thinks the bike is in the Tundra!
In order for the ECU to know what the engine temperature is there must be a thermistor. This is a resistor that accurately changes value as temperature changes.
Same thing with altitude. There is an air pressure sensor that measures atmosphere. This can change timing/A:F ratios.


I don't know where the thermistor is. Anyone?

I'm going hunting....

Motogiro said:

In the beginning the symptom seemed to get worse at higher engine temp. The coils were swapped and the condition existed and the miss changed to the opposite cylinders.

Does the bike run okay when cold? Is the ECU dumping lots of fuel because it thinks the bike is in the Tundra!
In order for the ECU to know what the engine temperature is there must be a thermistor. This is a resistor that accurately changes value as temperature changes.
Same thing with altitude. There is an air pressure sensor that measures atmosphere. This can change timing/A:F ratios.


I don't know where the thermistor is. Anyone?

I'm going hunting....

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You sure you pulled the correct coil pack?
Doesn't it share the coolant gauge temp for that? Also its a combo effort of the Air intake temp and engine temp to establish AFR (plus RPM, pressure, TPS, etc). There is also the slim chance that NEW coil is bad. These things do happen and it really complicates matters when replacing bad parts with new bad parts. Lets SAY ITS NOT the COIL(s); IIRC it will run in fail safe mode if it thinks either has a problem but it shouldn't be so NUTS as to flood the thing by dumping Gallons per minute.

To diagnose: One side of the coils go directly to the ECM. The other to the starting circtuit cut-off relay (Essentially +12V when all is well). So other than some ring back from the coils, you should be able to see battery voltage on one side of the coils (Red/blue trace) when running. Also, take note that the SAME LEAD powers the Fuel pump. Have you had any issues there? I'd be pulling every connector apart that touches the items listed below but the primary item is the Starting circuit cut-off relay with RED +12V in => Red/blue trace +12v out to coils. Sadly if not the coils the weakest link is the ECM and the wires between it. Do i hear DRY ICE TO THE CPU TEST???

In the path to kill the ignition is all of the following:
1. Main switch
10.Starting circuit cut-off relay
11.Sidestand switch
12.Neutral switch
17.Lean angle sensor
46. Engine stop switch
60.Clutch switch

Timing has crossed my mind, we tested the coil packs and they are throwing spark.

It does seem as though possibly to much fuel is being dumped in those 3 cylinders that have wet plugs.

And yes after we swapped the plugs it ran good until the bike gets hot. Took it down the street with no issues, came back ready to road test and didnt get off my street when it died at the stop sign and didnt want to turn over.

It does seem that what ever is causing this is getting worse and soon will completely fail.

UHcougarJohn said:

Timing has crossed my mind, we tested the coil packs and they are throwing spark.

It does seem as though possibly to much fuel is being dumped in those 3 cylinders that have wet plugs.

And yes after we swapped the plugs it ran good until the bike gets hot. Took it down the street with no issues, came back ready to road test and didnt get off my street when it died at the stop sign and didnt want to turn over.

It does seem that what ever is causing this is getting worse and soon will completely fail.

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But just because they throw spark in the open air it really means nothing under the load of combustion. Its more of "Warm Fuzzy" than a test that says IT WILL WORK 100%! The best you could hope for is that its throwing a nice white/purple spark (not orange/red). The next step in warm fuzzy is to throw some old plugs in that you can increase the gap step by step until it fails and arcs somewhere other than the plugs gap. Do this and study WHERE that arc-over occurred. As I said before, best tests are misting with water - if it leads to failing and arc over I wouldn't leave the house on it, Watching it in the dark, listening and lastly touching it. If knocks you on your @ss its bad. This is a last resort btw. Rubbing ones hands on the coil wires, caps, coil while running. Again - NEW doesn't always mean defect free. See above post for T/S steps.

Do you by chance have access to an oscilloscope?

PS - the injection system going wide open overly rich theory falls apart as the RPM increases. In that case; it should clean out and run better at higher RPM just as IF the injection system were normally ramping up reaching a higher duty cycle.