Possible Bad Coil Pack??

[TownsendsFJR1300]

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....

Several sensors I found that may be related:

Coolant temp sensor
Intake air sensor
Intake air pressure sensor..

I would think the coolant temp sensor in conjunction with the air intake sensor (and perhaps the air pressure sensor if at altitude) would relay their information to the ECU and allow the ECU, ie: if cold richen up the mixture. When at running temp, go back to its normal mixture (again depending on conditions)...

Is it possible the coolant temp sensor is relaying false info to the ECU keeping it in a "rich state" thus flooding it??


I didn't see any other sensors, for the ECU, to gather information from...

 

[Motogiro]

If the temp sending unit is the thermistor for the ECU and we think this could be an issue because the bike seems to die as the engine warms, we could disconnect the temp sending unit and put a fixed value resistor on the wire.

Measure the resistance on the sending unit while the engine is hot. Use that resistance and install a fixed resistor of that value on the wires. Start the motor and see if it stays running. It should still start cold and run a little lean as it warms up but then run okay after it warm up if this is the issue.

I don't think the air temp has anywhere as much influence on the ECU as the engine temp and I don't think there should be that much difference from cold to warm engine fuel mix to flood the engine. The other thing is if the the engine temp sensor was bad you should see the temp gauge go bananas unless it's a 3 wire deal with separate thermistor to the ECU or there is a separate thermistor on the motor to the ECU.

 

[TownsendsFJR1300]

I do know, as my bike warms from cold, high idle, obviously, the temp gauge eventually reads a number (dead cold it reads "LOW" on the digital gauge). As the temp rises, the idle drops and the bike goes out of "cold mode" and eventually into normal temp running mode and a normal lower idle...

I don't know of any other sensors that record the engine temp, for the ECU, besides those noted above, the water temp being the most important for the ECU to make some important decisions on wether to change the mapping or not.


I did have on my old FJR shop manual a section that showed how the FI /ECU changed mapping for different conditions (cold, accelerating, de-celerating, etc) however the book went with the bike when I sold it...

 

[UHcougarJohn]

Not sure about oscilloscope, I would have to ask around.

When I first started having this problem the bike would run at higher rpm fine even though coming to an idle or off an idle it would die, that's how I was able to get home by not stopping.

 

[TownsendsFJR1300]

Not sure about oscilloscope, I would have to ask around.

When I first started having this problem the bike would run at higher rpm fine even though coming to an idle or off an idle it would die, that's how I was able to get home by not stopping.

If its staying in "rich" (cold) map, that would explain the wet plugs, especially at idle, not wanting to idle as well when at operating temp....

 

[FinalImpact]

If its staying in "rich" (cold) map, that would explain the wet plugs, especially at idle, not wanting to idle as well when at operating temp....

As you can both see I'm not board with that. Bluburing RICH and dead are very different. As best I can tell its going from running to total misfire. Having been around 2 strokes and all kinds of other carb'd engines, even total momentary saturation is not the death nail.

Something else is up and you're loosing spark so until you do something different, the results will likely remain the same. Can you put the original coil back? I mean you said it got worse - does it stand to reason it will not be as bad with the half dead coil?

The impact of cold idle vs hot idle is very minimal VS bad TPS (for example). So is the original diagnoses wrong? Have you looked at all the connections? Anything green and growing?

 

[UHcougarJohn]

As you can both see I'm not board with that. Bluburing RICH and dead are very different. As best I can tell its going from running to total misfire. Having been around 2 strokes and all kinds of other carb'd engines, even total momentary saturation is not the death nail.

Something else is up and you're loosing spark so until you do something different, the results will likely remain the same. Can you put the original coil back? I mean you said it got worse - does it stand to reason it will not be as bad with the half dead coil?

The impact of cold idle vs hot idle is very minimal VS bad TPS (for example). So is the original diagnoses wrong? Have you looked at all the connections? Anything green and growing?

The coil pack did not solve or make the issue better so yes it was not totally or possibly even correct. But given the symtoms and variables at the time it made since. Both coils originally tested in spec but one of them was rite on the edge and that's the one changed.

We did check all connectons and we had 4 sets of eyes in a dark garage looking for glowing. We did introduce water at one point and something didn't like it but we couldnt quite trace it so we where not sure if it was the water or if the problem was just getting worse.

 

[TownsendsFJR1300]

As you can both see I'm not board with that. Bluburing RICH and dead are very different. As best I can tell its going from running to total misfire. Having been around 2 strokes and all kinds of other carb'd engines, even total momentary saturation is not the death nail.

Something else is up and you're loosing spark so until you do something different, the results will likely remain the same. Can you put the original coil back? I mean you said it got worse - does it stand to reason it will not be as bad with the half dead coil?

The impact of cold idle vs hot idle is very minimal VS bad TPS (for example). So is the original diagnoses wrong? Have you looked at all the connections? Anything green and growing?

With the initial symptoms and diagnosing, the coils looked to be the culprit.

Just to re-iterate from a previous post, did you see any arcing/carbon build up when you swapped the plug caps to the new coil?

Could it be a bad spark plug cap and you simply moved the problem to the new coil?

Also Randy,
You mentioned something that hasn't come up yet, just a shot in the dark....

UHcougarjohn, just for S&G's, have you checked the TPS thru the instrument panel?

At the top of the tech section is a post about TPS failure symptoms and how to check it... There should be NO SKIPPING of #'s either up or down... It won't take you but a couple of minutes to check it. Your bike was NOT in any TPS re-calls but it doesn't mean the TPS couldn't fail...

 

[Motogiro]

With the initial symptoms and diagnosing, the coils looked to be the culprit.

Just to re-iterate from a previous post, did you see any arcing/carbon build up when you swapped the plug caps to the new coil?

Could it be a bad spark plug cap and you simply moved the problem to the new coil?

Also Randy,
You mentioned something that hasn't come up yet, just a shot in the dark....

UHcougarjohn, just for S&G's, have you checked the TPS thru the instrument panel?

At the top of the tech section is a post about TPS failure symptoms and how to check it... There should be NO SKIPPING of #'s either up or down... It won't take you but a couple of minutes to check it. Your bike was NOT in any TPS re-calls but it doesn't mean the TPS couldn't fail...

+1 Most definitely this! I thought for some reason this was already done. I'm prolly thinking of another thread. Oh yeah deffo check the TPS!

 

[FinalImpact]

The coil pack did not solve or make the issue better so yes it was not totally or possibly even correct. But given the symtoms and variables at the time it made since. Both coils originally tested in spec but one of them was rite on the edge and that's the one changed.

We did check all connectons and we had 4 sets of eyes in a dark garage looking for glowing. We did introduce water at one point and something didn't like it but we couldnt quite trace it so we where not sure if it was the water or if the problem was just getting worse.

What we need to grasp here is that if an engine runs on said coil pack(s), ohming them rarely tells us of there health as its the break down voltage that we need to know but can not test.
Placing me in the same boat; Yes, I would measure the terminal to terminal ohms and terminal to output but its if it runs, it means little. Now if it changes when warmed in the oven for say 30 min at 180F and goes completly out of spec, well that would be something but I bet it won't.

Find a way to check the coil voltage as I said earlier and if an O'scope could be had, we may be able to overt just throwing money at it or you can take it in and throw money it.
Any FZ owners wish to swap ECM's with John?

 

[TownsendsFJR1300]

What we need to grasp here is that if an engine runs on said coil pack(s), ohming them rarely tells us of there health as its the break down voltage that we need to know but can not test.
Placing me in the same boat; Yes, I would measure the terminal to terminal ohms and terminal to output but its if it runs, it means little. Now if it changes when warmed in the oven for say 30 min at 180F and goes completly out of spec, well that would be something but I bet it won't.

Find a way to check the coil voltage as I said earlier and if an O'scope could be had, we may be able to overt just throwing money at it or you can take it in and throw money it.
Any FZ owners wish to swap ECM's with John?

Can a hair dryer / heat gun applied to the coil(s) (in a controlled enviroment-stopped, in the garage) be used to check the coils dead cold, then heat them on the bike and check voltages again heated up? At least to rule them out (or in)..

I'd still like to know if there was any evidence of arcing between the wire(s) and the spark plug cap(s)... Perhaps check resistance there as well...

 

[Piston]

I've been helping John out with this one or at least trying too… With dry plugs in the bike, it will run fine until it warms up at which point you can hear the bike stumble; if you twist the throttle slightly you can hear detonation so we have mostly let it idle (fouling plugs).
We have tested the coils cold and hot, wet and dry, no signs of arching anywhere. Of the original coils, one coil had much high resistance then the other at 175 degrees, so we replaced the coil. After the new coil was installed the symptoms changed to the point the bike would not start. We disconnected the fuel pump, cranked the bike over, clearing the excess fuel, then reconnect the pump and it would run for a minute or two. We then swapped the plugs and the symptoms returned to original. Therefore the coil pack had zero affect…

I’m leaning towards the theory that a sensor is malfunctioning, misinforming the ECU of the bikes status and therefore sending the wrong MAP…
John, See the post below. We need to rule out these 3 sensors.

Thanks for all the Help....:rockon:

Several sensors I found that may be related:

Coolant temp sensor
Intake air sensor
Intake air pressure sensor..

I would think the coolant temp sensor in conjunction with the air intake sensor (and perhaps the air pressure sensor if at altitude) would relay their information to the ECU and allow the ECU, ie: if cold richen up the mixture. When at running temp, go back to its normal mixture (again depending on conditions)...

Is it possible the coolant temp sensor is relaying false info to the ECU keeping it in a "rich state" thus flooding it??


I didn't see any other sensors, for the ECU, to gather information from...

 

[FinalImpact]

Find a way to check the coil voltage as I said earlier . . . .

Measuring the power to the coils with a meter capable of storing Hi and low Peak values quickly eliminates a big chunk of the bikes circuitry.

You really need another Fizzer to swap some parts with. . .

 

[Motogiro]

I've been helping John out with this one or at least trying too… With dry plugs in the bike, it will run fine until it warms up at which point you can hear the bike stumble; if you twist the throttle slightly you can hear detonation so we have mostly let it idle (fouling plugs).
We have tested the coils cold and hot, wet and dry, no signs of arching anywhere. Of the original coils, one coil had much high resistance then the other at 175 degrees, so we replaced the coil. After the new coil was installed the symptoms changed to the point the bike would not start. We disconnected the fuel pump, cranked the bike over, clearing the excess fuel, then reconnect the pump and it would run for a minute or two. We then swapped the plugs and the symptoms returned to original. Therefore the coil pack had zero affect…

I’m leaning towards the theory that a sensor is malfunctioning, misinforming the ECU of the bikes status and therefore sending the wrong MAP…
John, See the post below. We need to rule out these 3 sensors.

Thanks for all the Help....:rockon:

:welcome:to the forum and thanks for helping and clarification!

 

[FinalImpact]

I've been helping John out with this one or at least trying too… With dry plugs in the bike, it will run fine until it warms up at which point you can hear the bike stumble; if you twist the throttle slightly you can hear detonation so we have mostly let it idle (fouling plugs).
We have tested the coils cold and hot, wet and dry, no signs of arching anywhere. Of the original coils, one coil had much high resistance then the other at 175 degrees, so we replaced the coil. After the new coil was installed the symptoms changed to the point the bike would not start. We disconnected the fuel pump, cranked the bike over, clearing the excess fuel, then reconnect the pump and it would run for a minute or two. We then swapped the plugs and the symptoms returned to original. Therefore the coil pack had zero affect…

I’m leaning towards the theory that a sensor is malfunctioning, misinforming the ECU of the bikes status and therefore sending the wrong MAP…
John, See the post below. We need to rule out these 3 sensors.

Thanks for all the Help....:rockon:

That's very helpful. I'm just guessing here but i would think the ECm would detect such a grave error on the part of a single sensor and run in the limp home mode with an error on the dash.

have you guys tried baking the used plugs? A hand held propane torch is helpful. Not to hot tho.

Does it stink of RICH when it does run? Does it have CATs and if so, do they get hot? If being hit with raw gas they will get very hot!

 

[UHcougarJohn]

With the initial symptoms and diagnosing, the coils looked to be the culprit.

Just to re-iterate from a previous post, did you see any arcing/carbon build up when you swapped the plug caps to the new coil?

Could it be a bad spark plug cap and you simply moved the problem to the new coil?

Also Randy,
You mentioned something that hasn't come up yet, just a shot in the dark....

UHcougarjohn, just for S&G's, have you checked the TPS thru the instrument panel?

At the top of the tech section is a post about TPS failure symptoms and how to check it... There should be NO SKIPPING of #'s either up or down... It won't take you but a couple of minutes to check it. Your bike was NOT in any TPS re-calls but it doesn't mean the TPS couldn't fail...

I did not see any carbon build up and have tested the caps and they are all in spec.

In Diag mode the tps is also in spec. Has anyone had an issue with a tps that tested in spec in diag mode?

 

[Piston]

That's very helpful. I'm just guessing here but I would think the ECU would detect such a grave error on the part of a single sensor and run in the limp home mode with an error on the dash. !

I would assume the ECU would report an open or closed circuit or a sensor completely out of range, but would it report a sensor such as a thermister that was providing inaccurate measurements/data as long as the data was within the expected range?

Does it stink of RICH when it does run? Does it have CATs and if so, do they get hot? If being hit with raw gas they will get very hot!

At idle you could smell plenty of fuel, haven't got it off idle recently. Cats on a bike? I sure hope not, if that things has CATS they hid them good. John?


BTW we also checked the TPS throughout the range multiple times cold/hot and OHMed the CPS out, which was within spec (just don't remember the #'s. The plug caps were 9.02k to 9.8k, the book says they should be 10k, we should be good there.

Thanks,

Scott

 

[UHcougarJohn]

I've been helping John out with this one or at least trying too… With dry plugs in the bike, it will run fine until it warms up at which point you can hear the bike stumble; if you twist the throttle slightly you can hear detonation so we have mostly let it idle (fouling plugs).
We have tested the coils cold and hot, wet and dry, no signs of arching anywhere. Of the original coils, one coil had much high resistance then the other at 175 degrees, so we replaced the coil. After the new coil was installed the symptoms changed to the point the bike would not start. We disconnected the fuel pump, cranked the bike over, clearing the excess fuel, then reconnect the pump and it would run for a minute or two. We then swapped the plugs and the symptoms returned to original. Therefore the coil pack had zero affect…

I’m leaning towards the theory that a sensor is malfunctioning, misinforming the ECU of the bikes status and therefore sending the wrong MAP…
John, See the post below. We need to rule out these 3 sensors.

Thanks for all the Help....:rockon:

Thanks Scott I agree, we need to test these.

 

[Motogiro]

I did not see any carbon build up and have tested the caps and they are all in spec.

In Diag mode the tps is also in spec. Has anyone had an issue with a tps that tested in spec in diag mode?

I remember someone once said their TPS tested okay but it wasn't okay. Why would you go through the engineering and testing mode to test something that might still pass the test and be bad? Slowly turn the throttle. If the number change gradually and top and bottom numbers are in spec it is good.

 

[UHcougarJohn]

That's very helpful. I'm just guessing here but i would think the ECm would detect such a grave error on the part of a single sensor and run in the limp home mode with an error on the dash.

have you guys tried baking the used plugs? A hand held propane torch is helpful. Not to hot tho.

Does it stink of RICH when it does run? Does it have CATs and if so, do they get hot? If being hit with raw gas they will get very hot!

We have not baked the plugs.

Yes it smell rich when it runs and yes it has cat, next time I fire it ill make note I'd the cat gets hot.

Thanks everyone for your help:thumbup: