08 FZ6 stalling, strange idle

[MooseJuice71]

Just picked up an 08 FZ6 with 3k miles and am having trouble with idling. I read the TPS sticky and since mine is an 08, it is not recalled. Here is a description of the problem:

After warm-up, if I rev the engine and quickly close the throttle, the RPMs drop quickly down below normal idle speed. The higher I rev it, the lower the RPMs drop before returning to normal idle speed. If I rev over 7k and quickly close the throttle, the RPMs drop so low that it stalls.

Also, after warm-up if i quickly rev the engine up and down, the engine seems to bog down and stall.

Any idea what this could be?

Thanks,

John

 

[The Dude]

:welcome:

What is the "normal idle speed" you're referring to?

It should be 1250-1350 RPMs. It sounds like your idle is set too low. If your "normal idle speed" is below that range, it's easy to fix. Get a phillips head screwdriver and look for the adjustment screw on the left side of the bike. It's right under the tank (in the area where your left knee normally sits). You can stick the screwdriver right in between the tank and the frame to access it. Turn it clockwise to increase idle speed. Hopefully that will solve it.

 

[MooseJuice71]

Thanks for the reply!

Normal Idle speed is about 1200 RPM, so unfortunately I suspect it might be something else. I looked up TPS problems on youtube and it appears that my problem may indeed be TPS, considering the videos demonstrated the same symptoms I am experiencing. Does this sound like a TPS problem? If so, where is a good place to buy a replacement TPS?

 

[The Dude]

I thought TPS was only an issue on first generation FZ6s.

Is that idle speed once the bike is up to operating temp?

You may need to have your throttle bodies synced. First, I think you should experiment with idle speed. It's super easy to adjust it up and down, and it might just solve your problem.

 

[MooseJuice71]

Ok, I will adjust my idle speed and see what happens. Should the bike be running while I adjust this or should I turn it off, adjust and then check the speed?

Yeah, I thought the TPS was only for 04-05 models. But even if they fixed the TPS in the later models, it is still possible to get a faulty one right?

 

[The Dude]

Should the bike be running while I adjust this or should I turn it off, adjust and then check the speed?

Leave it running so you can see the effects of the adjustment. I would make sure the coolant temp is up in the 165-185 range before you make adjustments.

 

[FinalImpact]

Ok, I will adjust my idle speed and see what happens. Should the bike be running while I adjust this or should I turn it off, adjust and then check the speed?

Yes, have it running and count the turns needed to correct it.

Yeah, I thought the TPS was only for 04-05 models. But even if they fixed the TPS in the later models, it is still possible to get a faulty one right?

Agreed, in the ideal world yours is fine. But it could be the issue. Don't discount it. I'd measure it and see if it reads correctly. If so, inspect the spark plugs and don't disregard the Fuel quality either as it could be directly related too. Try a different supplier and perhaps some injector cleaner too.

 

[MooseJuice71]

Thank you both for the help, I really apprieciate it! I will adjust the idle speed and check the TPS reading after work today. If that reads ~17 closed and ~100 open, it can't be the TPS, correct? If that reads out ok, then I will move on to the plugs and air filter. If those are fine I will try new fuel as well. Hopefully I will find the problem within all of these checks! I will report back with the results.

Thanks again for all the help!

 

[FinalImpact]

. . . .If that reads ~17 closed and ~100 open, it can't be the TPS, correct? If that reads out ok, . . . .

FYI: that's still a ball park. It needs to be a continuous output linear in nature. Any breaks or inconsistencies gives the ECM bad data about the throttle plate angle.

Think of it this way:
With a pencil draw a horizontal line on a paper. The bottom is idle the top is WOT.
Now erase 6 random sections.

Those voids represent a loss of data or incorrect data being sent to the ECM. But the only points you can measure accurately relative to position are start and stop points. The test doesn't mean its free of fault.

If it passes the test I suggest you slowly rotate the throttle and watch the meter. It should be smooth steady increase. Make sense?

The air filter if plugged could hurt throttle response this. Check it while the tank is up.

 

[mrphotoman]

after i installed the twobros exhaust and juicebox mine did the same thing 2008 fz6. i turned the idle up by 200rpms and the problem went away. it was idling a little too low, it is super easy to turn up the idle, give it a try.

 

[MooseJuice71]

FYI: that's still a ball park. It needs to be a continuous output linear in nature. Any breaks or inconsistencies gives the ECM bad data about the throttle plate angle.

Think of it this way:
With a pencil draw a horizontal line on a paper. The bottom is idle the top is WOT.
Now erase 6 random sections.

Those voids represent a loss of data or incorrect data being sent to the ECM. But the only points you can measure accurately relative to position are start and stop points. The test doesn't mean its free of fault.

If it passes the test I suggest you slowly rotate the throttle and watch the meter. It should be smooth steady increase. Make sense?

The air filter if plugged could hurt throttle response this. Check it while the tank is up.

Ah, I get it. I just ran out at lunch to check the TPS and it is 16 Closed/101 Open. I will check to make sure it is a linear progression. Turning slowly, I should be able to see the number increase by one? What would it look like if there was some bad data? Would the meter read nothing at those points?

 

[FinalImpact]

Ah, I get it. I just ran out at lunch to check the TPS and it is 16 Closed/101 Open. I will check to make sure it is a linear progression. Turning slowly, I should be able to see the number increase by one? What would it look like if there was some bad data? Would the meter read nothing at those points?

A +1 increase is not likely obtainable by twisting the grip. IIRC the cam associated with the throttle cable is slightly eccentric which means its not going to be linear 1:1 rate at the throttle shaft aka TPS. Anyway, A dead spot where there is no change and then see the meter jumps or if the meter drops and flutters would indicate a worn or faulty TPS.

The range used most will be that just off idle so spend the most time there making sure it gradually increases without jumping.

** Also snapping the throttle back a dozen times and confirming you get the same ### each time would be important! **

 

[LadyDi]

Just picked up an 08 FZ6 with 3k miles and am having trouble with idling. I read the TPS sticky and since mine is an 08, it is not recalled. Here is a description of the problem:

After warm-up, if I rev the engine and quickly close the throttle, the RPMs drop quickly down below normal idle speed. The higher I rev it, the lower the RPMs drop before returning to normal idle speed. If I rev over 7k and quickly close the throttle, the RPMs drop so low that it stalls.

Also, after warm-up if i quickly rev the engine up and down, the engine seems to bog down and stall.

Any idea what this could be?

Thanks,

John

Is it super hot out? Perhaps the fuel octane is too low and your engine is subject to detonation?... just a guess.

 

[The Dude]

What's the word, MooseJuice? Did you get it straightened out?

 

[bugsterkiton]

Hi Moose,
Just an idea, try to change completely your "old" fuel.(3k for3 years...) I had the same problem because the bike didn't ride for a while(6 months). The fuel quality decreases after only 1 month with the time and the temperature. After that let the engine burn some new fuel and than check the value of the idle.Sorry for my american, I don't know the technical vocabulary.

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