Jump to content
TBEXX

FZ07 Sputter/Misfire? PLEASE help

Recommended Posts

TBEXX

My bike has been having this weird issue for about a month now where it makes this weird sputtering sound, it feels like it’s lagging and losing power when it does happen. Sometimes it’s not so bad and sometimes it’s awfulll, so it’s not consistent. and only happens when there’s load and I’m actually on and riding the bike... I can’t get it to replicate on the bike stand.  Seems to act up the most around 6k RPMS. makes the bike sound and feel awful, dont feel safe riding it like this.. 
Thought it may be a fuel issue,  so I tried to swap the fuel pump, spark plugs, coils, entire throttle body assembly with injectors, fuel rail, and all, even the ECU just in case. Deleted the kickstand switch and o2 sensor, even did a throttle body sync. anndddd still no luck.
 

Please tell me someone out there has had this same issue and how did you fix it?? 

I tried to get a video while riding: https://youtu.be/n9QJCP7BOSY

Share this post


Link to post
Share on other sites
mjh937

@TBEXX, have you done any modification to the exhaust or intake?  It is hard to hear what is going on from the YouTube post but have you checked for exhaust leaks?

  • Like 1

Share this post


Link to post
Share on other sites
TBEXX
13 hours ago, mjh937 said:

@TBEXX, have you done any modification to the exhaust or intake?  It is hard to hear what is going on from the YouTube post but have you checked for exhaust leaks?

I bought the bike used almost a year ago with a two brother exhaust already on it, and havent done any other mods to it since. 

I have tried to look myself (im very limited on experience to be completely honest) but I could not find any leaks

Share this post


Link to post
Share on other sites
geophb

Yea I hear the sputtering in the video. You have done most of what I would say to try too.  You replace with a new or used stock ecu?

Does it correlate with bumps in the road? maybe there is something loose, like a ground, plug or battery connection.  Did you try fiddling with the kill switch while its doing it? Maybe the switch is randomly cutting in and out.  

Was thinking maybe crank or cam sensor but they usually either work or they dont.  To me it sounds spark related as that is more prone to intermittent problems than the fueling side.

Share this post


Link to post
Share on other sites
CarGuy7a

It's possible that it may be tune related. I have heard this on other bikes that had tune problems and I've even heard it on my FZ07 the first couple rides I did when the tune was way off with the stock O2 being disconnected while I was starting to tune with the autotune and PCV. What tuning setup does your bike have on it? PCV, FTECU? Is it showing any codes on the dash? If it's extremely rich, it can cause a misfire sound.

I had this problem when I converted a carbureted CRF450R for street use, it was way rich when cruising and sounded like a misfire. I went as far as even buying a brand new CDI box and it didn't fix it. I went through every electrical circuit on the bike and found nothing wrong. Decided to buy a 12v powered AFR gauge and the bike read 10 AFR at cruising!!!!! I jetted it down to 13.2AFR ran like a champ with no misfire go figure.

Extremely rich or lean mixture can be confusing and the symptoms are almost identical unless you've experienced them enough times to pick out the differences. Extreme rich will be sluggish on power and have a misfire sound while holding a steady throttle position. Extreme lean will also be sluggish but the engine will cough (masking a misfire sound) but will also surge very badly while throttle position is steady. Really the easiest way to tell is with an AFR gauge and wideband O2 while running the bike in the problem area.

It could also be a problem related to the deleted kick stand switch. I know I had problems with the bike acting weird just like your's is when I deleted the clutch switch and tied the wires together. The switches run into the ECU and run an entirely different fuel map when those switches are either a complete or incomplete circuit. I know when I shorted the clutch switch wires to simulate the clutch being pulled in all the time so I could start the bike in any gear, I got the same symptom as yours, misfiring and sluggish power. Try that first, put your kickstand switch back on and ride the bike and see if you get the same result.

This might not be the case with your bike just throwing out what I've experienced in the past and something you might look into if you don't have much knowledge what the previous owner did to the bike. I would start with that kickstand switch first without changing anything else. Hook it back up, ride it if the problem goes away then that's what it was. Go one step at a time because it will most likely only be one thing causing the issue.

Share this post


Link to post
Share on other sites
geophb
25 minutes ago, CarGuy7a said:

The switches run into the ECU and run an entirely different fuel map when those switches are either a complete or incomplete circuit.

No. Not the case.

Deleting the kickstand switch cut wont matter, ecu doesnt care, as it would think its always up.  Clutch switch I could see having issues, maybe but doubtful, as the ecu thinks the clutch is always pulled in. This is assuming wiring is done correctly.

I would leave the clutch switch alone because you can start in neutral without clutch pulled in stock form. 

Share this post


Link to post
Share on other sites
CarGuy7a
Posted (edited)
45 minutes ago, geophb said:

No. Not the case.

Deleting the kickstand switch cut wont matter, ecu doesnt care, as it would think its always up.  Clutch switch I could see having issues, maybe but doubtful, as the ecu thinks the clutch is always pulled in. This is assuming wiring is done correctly.

I would leave the clutch switch alone because you can start in neutral without clutch pulled in stock form. 

I've done it. I know it runs differently and I know it runs worse when the clutch wires are constantly contacted. I've installed a normally open switch in place of the clutch switch (so I could press it and still be able to start in gear) due to me wanting a completely different clutch perch setup that doesn't accept the clutch switch (RSC to be exact) I've made an entire thread about it here. If I have the bike in gear clutch pulled in and button open (simulating the clutch being engaged) the idle raises about 300RPM. If I simply push that button in telling the ECU the clutch is pulled in the idle drops so it definitely 100% has something to do with fueling and ignition in the ECU. If you look at the wiring diagram in the service manual (I just did to confirm) you will notice that BOTH the sidestand switch and clutch switches trace directly into the ECU and other components in the fuel system and when those are altered it definitely changes something in the fueling and or ignition. The kickstand switch might not matter, but then again I thought the same about the clutch switch and it definitely does. 

The engineers are doing some weird stuff to the programming of these ECU's from the factory unlike the old days of carbs and CDI boxes where the safety switches didn't matter whether they were there or not. 

Edited by CarGuy7a

Share this post


Link to post
Share on other sites
RobZilla
Posted (edited)

This is interesting. It sounds like the issue is the worst at peak torque. Are you running any type of fuel management, ecu flash or piggyback, or is it a stock ecu?

Edited by RobZilla

Share this post


Link to post
Share on other sites
geophb
Posted (edited)
36 minutes ago, CarGuy7a said:

I've done it. I know it runs differently and I know it runs worse when the clutch wires are constantly contacted. I've installed a normally open switch in place of the clutch switch (so I could press it and still be able to start in gear) due to me wanting a completely different clutch perch setup that doesn't accept the clutch switch (RSC to be exact) I've made an entire thread about it here. If I have the bike in gear clutch pulled in and button open (simulating the clutch being engaged) the idle raises about 300RPM. If I simply push that button in telling the ECU the clutch is pulled in the idle drops so it definitely 100% has something to do with fueling and ignition in the ECU. If you look at the wiring diagram in the service manual (I just did to confirm) you will notice that BOTH the sidestand switch and clutch switches trace directly into the ECU and other components in the fuel system and when those are altered it definitely changes something in the fueling and or ignition. The kickstand switch might not matter, but then again I thought the same about the clutch switch and it definitely does. 

Went through wiring diagram. You are correct. Clutch switch connected to ecu, and you obviously tested it and it does something. Kickstand is just a basic switch to ground so that won't matter though. 

Might have idea for you, will pm, as to not derail thread too much.

Edited by geophb

Share this post


Link to post
Share on other sites
CarGuy7a

Curious if the OP found anything.

Share this post


Link to post
Share on other sites
Voo216

Not sure how much of a help this will be for you knowledgeable guys out there, but I'm the original owner of mine and I'm having a similar issue to the opening poster. I dont mean to hijack the thread, my hope is that by being able to provide input about what mods I've done to mine we can narrow down what the issue is. My setup is as follows...

2018 MT-07, Akrapovic titanium (db killer removed), MWR high performance air filter, ECU reflash done by 2wheeldynoworks

I feel its worth noting that my bike never did this stock or after putting the exhaust on. I had the standard backfiring and popping after switching the exhaust out but never any performance issues. I did the air filter and ECU flash probably 3 or 4 months later (and at the same time). The backfiring/popping are gone like they should be, but the problem has been present ever since. The main difference for me is that it is extremely inconsistent.

My first reaction was that it was a fuel mapping issue, but there are periods where I will ride for 3 or 4 weeks at a time and never experience it happening at all. I've mostly convinced myself its not the ECU flash, seems like if that were the issue it would be present all the time. Usually for me, it seems to present itself after large amounts of rain (I park outside). The first 2 days after a lot of rain it does it pretty often, any other time its completely fine and is a symptom that I can't replicate. 

I never have idling or stalling issues. For me its always right between 5000-6000 rpm, and usually only when under heavy throttle. Also seems to occur more when I'm under heavy throttle while also on an incline. The engine never completely shuts off, sometimes its just a sputter like you hear in his video, but some times its also like you just completely took your hand off the throttle for a second. Just passing through the rev range doesn't seem to do it, the engine has to really be under load for it to happen. It's happened in low gears a few times, but usually it seems to always be in 4th, 5th, or 6th.

Any input is welcomed!

Edited by Voo216

Share this post


Link to post
Share on other sites
CarGuy7a
1 hour ago, Voo216 said:

 Usually for me, it seems to present itself after large amounts of rain (I park outside). The first 2 days after a lot of rain it does it pretty often, any other time its completely fine and is a symptom that I can't replicate. 

That sounds like the water getting into the electrical system somewhere causing the problem.

Share this post


Link to post
Share on other sites
rfmueller

"Thought it may be a fuel issue,  so I tried to swap the fuel pump, spark plugs, coils, entire throttle body assembly with injectors, fuel rail, and all, even the ECU just in case. Deleted the kickstand switch and o2 sensor, even did a throttle body sync. anndddd still no luck."

The symptoms you're describing are that of a bad variable resister:  The throttle position sensor is likely to be either dirty or defective,  or with a dead spot or a short from the rain/moisture.  It's cutting your fuel supply.  You may be able to fix it by simply opening and closing the throttle very quickly about a dozen times which can wipe and clean the carbon or debris out of the way.  Otherwise, it sounds like you need to replace that sensor.  It's not too hard:  Measure the resistance of the sensor in the idle position, EXACTLY with an ohm meter, then install the new one in EXACTLY the same position, making sure you end up with EXACTLY the same resistance at idle.  There are some fancy ways of interfacing with the computer as well, but you'll need to check the service manual or Youtube for those.

 

Share this post


Link to post
Share on other sites
Voo216
15 hours ago, CarGuy7a said:

That sounds like the water getting into the electrical system somewhere causing the problem.

I'd agree that seems to be one of the most likely situations, but how to proceed from there? I wouldn't have any idea about where to start or how to know if I've found it. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×

Important Information

By using this site, you agree to our Terms of Use.