Loss of top end power, now running on 2 cylinders

[cmdb]

Hello all,

I recently bought a 2010 Fazer FZ6 S2 with ABS with 22,000 miles. The ABS doesn't work at the moment, but that's a topic for a different day...

Timeline of events:

• First, I noticed that the bike wouldn't rev past about 10k rpm.
  The bike would pull hard to 10k, then the engine light would come on and the bike would lose power, refusing to rev any higher. In fact, as the power reduced, the rpm reduced and the engine light went out again. Then power was restored until I reached 10k rpm again, and the cycle repeated. It felt like a slightly slow, but very aggressive, rev limiter and the EML would flash with each dip in rpm. In neutral, the bike revs to redline and the actual rev limiter.
• I figured this was probably spark related, so I bought a service kit, and replaced the spark plugs. This made no difference.
• I checked the bike for codes and it was showing code 34 (Open circuit is detected in the primary lead of the ignition coil (# 2, #3)). I then found that my bike had 2 identical coils fitted, with leads labelled 1,1,4,4, rather than 1,2,3,4 - not sure if this is relevant.
• I figured I'd play it safe and bought 2 used coils with leads etc, off a low mileage bike. Figured I may as well replace the bad coil and pre-emptively replace the good one. These coils were now slightly different, such that the leads were labelled 1,2,3,4.
• Fitted these to the bike and it made no difference. Still getting code 34 and a refusal to rev past 10k.
• I saw someone suggest swapping the coils over to see if the fault moves from cylinders 1/4 to 2/3. I figured there was a very slim chance I'd replaced a bad coil with another bad coil, so I changed them over. Coil 1/4 now sits where coil 2/3 used to sit, and feeds cylinders 2 and 3; and vice versa.
• Bike started and initially ran fine, went for a test ride but about 3 minutes in the engine light came on at around 5k rpm, with associated power loss. This was much lower than normal. The power would come and go for the next few minutes, but ultimately it got to the point where the engine light was on constant, and the bike was running on 2 cylinders. Lots of vibration, very little power.
• Limped it back home and checked the error codes... no error codes reported! Well, under diag 61, it displays 00 (no errors logged) but under diag 62, which shows the number of codes logged, it displays 01. So, it knows it has logged a code but won't tell me what it is. Very weird.

I'm now at a bit of a loss, but I am suspecting an ECU fault. I've looked online for a 2nd hand ECU but there aren't many, and none for the ABS model, which I believe uses a different ECU? The ones currently for sale are also for the S1 version.

There are a few companies who seem to suggest that ECU repair might be an option. I wonder if this is my best bet.

Not sure what would need to be done regarding coding, but I do have the red key. I'm in the UK so the bike has an immobiliser.

Of course, I also don't want to be spending money on bits that won't fix the bike.

Does anyone have any ideas or suggestions? I'm also open to the suggesting of setting the thing on fire at this point!

Thanks in advance

 

[Gary in NJ]

Get a multi meter on the coils and provide a reading for the primary and secondary. I can’t follow along with random part swaps…it makes diagnostics impossible. Also check the voltage of the (+) at the coil…is should be very close to the static voltage of the battery.

 

[cmdb]

That's fair. I probably made it too complicated to be honest; essentially the problem didn't change when I replaced both coils, but then I switched the new coils around and it got worse.

But for the avoidance of doubt I've cracked out my multimeter and tested the coils I took off the bike, from when the problem first started. Primary readings of 2.0 and 2.0. Touching the leads together gives 0.3.

Secondary readings are 14920 and 14690.

 

[Gary in NJ]

Your coils check out fine. Now check the voltage at the input. If that is within a few tenths of the battery voltage then your ignition system checks out. You could have intermittent ignition due to a faulty side stand switch or the STOP switch by the throttle.

If all of that checks out as ok, then fuel starvation due to a clogged fuel pump screen would be a good place to start looking.

Is this bike stored outdoors?

 

[Motogiro]

Also because coils are high voltage secondary the high voltage can exhibit break down at different ambient and dielectric conditions. DC measurement are the best place to start but there may be intermittent failure because of breakdown at high voltage.
A transistor in the ECU may also be failing. The transistors that provide the ground path for the coils may be at fault and the best way to determine that might be with an oscilloscope on the ground/low side of the offending coil when the failure occurs.
I would also run a temporary jumper across the kill switch to insure there is full current through that path.

 

[Gary in NJ]

To Clif's point above, if any of the coils are showing evidence of cracking, even though they may pass a ohms test at room temperature, they are technically failed as the performance will change over temperature.

 

[AkifLed69]

I can feel you, i had a similar issue. It was the ecu. If you test your ignition coils and the are ok
Which one do you have? I had the fua0018.
In polland are alot of ecus or you could send your ecu to carmo electronic in the Netherlands. But you need to be sure.

 

[cmdb]

Apologies for the slow reply, and thanks for all the answers so far.

None of the coils have shown any cracking.

I can try to jump the kill switch to rule it out, but the bike never cuts out, and the failure is consistent enough that it doesn't seem to me to be a loose connection anywhere. Still, worth a go when I get a chance.

In the meantime, I will remove the coils I've just installed and check those on a multimeter as well, and then revert them back to how they were when the bike was at least rideable.

I also tested the spark plup caps. It was hard to get a reading , but 3 of them gave me around 9000 ohms, but one of them won't get a reading at all. So maybe this is faulty?

I then attached 2 of the good caps to a good coil and tried measuring resistance of the entire thing, but got no result/infinite resistance. The method was the same as measuring the secondary coils, but this time with the spark plug caps installed. I'd have expected the resistance to be the sum of the secondary coil plus both plug caps?

As for the ECU, I have emailed Carmo electronics who say they can help, but they say they need the immobiliser too. Removing this looks to be beyond my ability, so will be a garage job, unless anyone has any experience of getting a repair without removing the ignition barrel.

 

[Gary in NJ]

When I replaced my ignition key set I simply drilled the heads off the tamper proof bolts, remove the shank with pliers, and when I reinstalled the replacement I used regular cap head screws.

 

[cmdb]

To be honest, I'm worried that I'll end up with one bolt out and the other only half out, with the bike now unfixable and unrideable!

In the meantime, today I started the bike and it started on all 4 cylinders first go. I then removed the other coils and measured them on a multimeter and put them back in and went for a test drive. It continued to run on all 4, but with the same problem as it had originally i.e. won't rev past 9500rpm or so unless the clutch is in, engine light comes on at high rpm only. For the time being it is at least usable whilst I figure out what to do with it.

 

[cmdb]

In case it helps, I filmed the problem today.

Failure mode is very slightly different to how I described, perhaps it is related to things like throttle position and engine load. In first gear it will reluctantly increase in rpm.

 

[Gary in NJ]

I would suggest a compression check for an engine that won’t make power under load.

 

[cmdb]

It's not obvious from the video, but when it loses power it's like a switch is pushed and a bunch of power is lost. Up until that point it pulls fine. It's only under load *and* high rpm