Coils possibly gone bad?

[Steinrawr]

Hello fellow riders, I turn to you for hope!

My Fz6 '05 doesn't run smoothly. It's been staggering for a while, and I've had some problems with power loss, and rough idling with drops from 1300rpm to 900rpm, and even stalling on idle. (VIDEO OF PROBLEM)

I've fiddled about for a while now, checking what I could find. Throttle body looks nice, leads have correct specs and spark plugs are completely new with correct clearance.

I think I might have narrowed it down to the coils. But the strange thing is: The bike ran, but now that i check the coils, the readings I get indicate nothing should've worked:

Both coils read ~2k ohms on input. I cant read anything on output. The inside looks a little corroded, but I haven't managed to get a connection at all.

What do you think?

 

[fazil]

It can be a TPS (Throttle position sensor) problem, i also hava a 2005 Fz6 and had similar issues. Yamaha has changed it with a new one free.
There was a recall for some of the 2004 and 2005 models. Check this thread below:

http://www.600riders.com/forum/fz6-technical/181-throttle-position-sensor-issues-you-experiencing-poor-idle-mileage-stalls.html

 

[TownsendsFJR1300]

Can post some pic's of the corrosion?

Their obviously putting out spark (at least part of the time) or it wouldn't run.

Re the sync, that needs to be adjusted/checked with a tool, eye balling like that don't count...
Out of sync would help with the idle but it does sound like a misfire, especially with the up and down idle.

A lazer temp gun pointed at the header, right where it exits the head would narrow down what cylinder / coil
isn't firing with a cooler temp showing. Spritzing some water at the header (same area), can often give you an idea as well

A good cylinder firing will evaporate the water much faster than one misfiring...


How old is the fuel in the bike also?

 

[Steinrawr]

Thanks for the quick replies!

Problems are identical with first answer. I checked with diagnose, and I don't have readings within the parameters specified for the throttle. I get 19 on no throttle, and 104 on max. Should be between13-16 and 94-100 if I remember correctly.

Also: fuel is brand new, and all else seems to be okay.

 

[TownsendsFJR1300]

Did you read the TPS link Fazil posted?

While your #'s are out a little it won't hurt anything and certainly won't screw up the idle IF THE TPS IS GOOD.

Doing the test thru the dash is fine, your looking for any missing #'s in-between, skipping, etc.

Even with ^^, the TPS can still be bad and not show.

IMO, you need to contact Yamaha with your serial # and see if it falls inside the re-call...

Its very possible the culprit...

Pic's of the corrosion?

 

[FinalImpact]

It really sounds like the ignition is just not there on two holes....

The squirt bottle of water to the headers well tell you which one!

Also, because it was ok cold and failed when warm, it is another tell tale sign that coils fail in that manor.

FWIW: coil spade "+" to spade "-" is like 2.0 ohms.
Lead to lead is 15k ohms... there should be no continuity from spade lugs to coil outputs.

Lets say you use the water spritz and find cyl 2&3 are cold.
Now you if ohm the coil on 2&3 and they measures bad, yes, you may have a bad coil and you replace it and all is well.

However, there is potential the ecu died first and the coil is collateral damage!!!

In this case, you need to swap coil inputs and outputs and see if the problem follows the coils or remains at cyl 2&3 as the ecu is the source of the problem.

Another test is time how long it runs from cold until it misfires, let everything cool and unbolt the ecu and surround it in ice packs. Do your run test. If it runs longer before it misfires, a indication the ecu is defective!

 

[Steinrawr]

Thanks FinalImpact.

I did a spark-test, where all plugs fired nicely with a clear blue spark. To me, and a few I've spoken to, this indicates that the problem most likely is not on coils/wiring. Perhaps ECU.

I will take your suggestion to consideration when I get the bike back together, but anyhow mention it and discuss it with a garage tomorrow.

 

[FinalImpact]

Also, when trying to make coil wires reach for a test run (coil swapping) the leads being swapped on waste spark has no impact.

Meaning you can reverse 1 & 4 or 2 & 3 and it is going to start and run if those coils have spark energy to deliver!

 

[FinalImpact]

Take your used plugs and open the gap to say 0.070" and if when warm and firing a purple blue spark, yes, they may be ok! But heat does induce failure. Keep that in mind.

 

[FinalImpact]

[MENTION=27235]Steinrawr[/MENTION] so what came of this?

 

[Steinrawr]

Sorry for being slow. Ive checked everything I can, and need a garage to help me. There's a 3w waiting time for an appointment, so no cruising for me.

Based on Mye explanation the garage also suspects the sensor to be at fault.

 

[FinalImpact]

I hope that is what it is. I find it odd that at steady state it cuts in and out like that.

Have you jumped the kill switch? I.e. bypass it so the coils get all energy? Do you use the kill switch?

They have failed plenty of times...

If it were mine I would remove the battery, airbox and unplug and inspect every electrical connection. Do not forget the ECU and fuses, eveything under both side pods and between the frame rails. You may not find anything or you may find corrosion, burns, or some damaged conductors!

Id be looking before paying a shop!!!

 

[Steinrawr]

I forgot about the ECU, but my local garage did not:

I figured out the problem here, with help from a local garage:

• Throttle body needed adjustment
• ECU contacts had verdigris on contacts
• Verdigris caused Coil damage to Coil firing cyl. 2 & 3

This caused my problems. New coil, and cleaning up the ECU as well as adjusting the TB fixed it. cost: 5500 NOK (~USD $700)

 

[Steinrawr]

Solution: ECU had moisture in it, causing both coils to fail. Also my TB was out of place, and needed adjusting.

ECU was cleaned, coils replaced and now it's somewhat fine. It was perfect for a week or three, but the ECU seems to have taken permament damage, as some of the symptoms have come up again: rpm-drops when idle, down to 1000rpm, and some loss of power at low rpm.