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Discussion Starter · #1 ·
Well my bike has been idling really rough when the throttle is closed. I bought a power commander for my exhaust and corrected the a/f ratio at idle and it still won't go away. Last night I hooked up the power commander to load a map that I averaged out with two difference maps. I went into the menu to check and set the throttle position to make sure that it wasn't something that simple. I noticed that when the throttle is closed and the bike is off or running, the throttle position is all over the place. I realized that it is moving in sync with the rough idle.

I had my tps replaced a month ago and I had the same problem with the previous one. Is this really my second defective tps? It reads fine on the gauge sensor, but the power commander is saying it is moving.

Can someone else that is having the idle problem look at the their throttle position in the power commander software and verify that it is moving?
 

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Did you reset the throttle position for the PC using the PC software? I did it so long ago that I can't remember, but I believe you have to set it for 0% throttle and then 100% throttle. Maybe that just needs to be reset.
 

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Discussion Starter · #5 ·
ktravelet said:
sync the throttle bodies lately?
I assumed they did this at my last service when they did the tps last month. Perhaps they didn't...
Although my main concern is what would cause the sensor to jump around when the bike isn't running and I hook up the 9v to the power commander.
 

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Sidehacker Extraordinaire
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How much does it jump around? For reference, my closed throttle reading is 5192 and it'll move about +-50 all the time. It's nothing to worry about. Are you saying it's jumping up to like 7-8000? If so, that's a problem.

I would trust the PC3 sensor information over the DIAG mode display. The majority of people who had bad TPSes did not show any problems in the diag mode readout. It's just not sensitive enough. When mine went, it eventually went bad enough to trip the check engine light, but it still didn't always show a problem in diag.

It does sound like TPS failure. Out of synch TB's will NOT cause the TPS readout to change at all. Misfiring spark plugs will not cause it. Vacuum leaks, after market exhaust, holes in the cats, and El Nino won't cause it. The only thing that will change the TPS reading is twisting the throttle, or the sensor is bad.

I suppose it's possible that when they replaced the TPS, they simply grabbed one off the shelf instead of using the new revision. The part number on it should tell you the truth about what they did.
 

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Discussion Starter · #14 ·
Jeepcoma,
This is what I was thinking. I saw them pull the part off the shelf. I will check it against the recall tech sheets and see what I can figure out. I called another dealer and he told me a new tps is $130 and that I should deal with my shitty dealer who did the recall. (who keeps trying to rip me off)

If yours moves around a little, I feel that it must just be the throttle body sync. Mine isn't moving around more than 50 or so and is around 5230. If yours does that and idles right, then I guess I just need to sync the throttle body.
 

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I know that this thread is quite old.. I am reviving it as a reference to anyone searching this problem in the future...

Idle speed on fuel injected bikes is controlled by manipulating the throttle body to achieve whatever idle speed is chosen in the ecu. In cars ignition timing is varied as well (on a "quick" feedback loop while throttle position is used on a slow feedback loop. When you install a free flowing exhaust, the reduction in back pressure causes the bike to hunt and overshoot on idle. I'm
Not sure if bike tuning software has this function but increasing the idle speed generally works well to stabilize the idle on turbo'd cars and could help fix the problem. Or just live
With the loping idle cause it sounds pretty damn sweet!
 

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The Angry Blue Mantis!
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I know that this thread is quite old.. I am reviving it as a reference to anyone searching this problem in the future...

Idle speed on fuel injected bikes is controlled by manipulating the throttle body to achieve whatever idle speed is chosen in the ecu. In cars ignition timing is varied as well (on a "quick" feedback loop while throttle position is used on a slow feedback loop. When you install a free flowing exhaust, the reduction in back pressure causes the bike to hunt and overshoot on idle. I'm
Not sure if bike tuning software has this function but increasing the idle speed generally works well to stabilize the idle on turbo'd cars and could help fix the problem. Or just live
With the loping idle cause it sounds pretty damn sweet!
This has me wondering if my scorpion exhaust is the cause of my loping idle. my bike only lopes at idle when it's warm and I restart it and will lope for maybe 30 seconds and then start idling smooth. Also on cold starts it always idles smooth. Strange.
 

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I would think so.. The way I think about it is a restrictive exhaust will keep a constant backpressure at the exhaust ports.. When you eliminate that backpressure with a free-flowing exhaust, the pressure varies and along with it your idle.. Problem is that modern EFI bikes use the throttle body to achieve a set idle speed.. So the feedback can sometimes amplify the idle error.
 

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Where do you get this info? While it may apply to other motorcycles, it does not pertain to the FZ6. The FZ6, unlike a sophisticated system on a car, has no method of adjusting air flow on-the-fly to regulate idle speed. The only thing that adjusts the throttle plate position is the operator's right hand; with no input the throttle plates are 100% closed. Idle air is a separate circuit that bypasses the throttle blades and is regulated by the "master" idle speed screw and a secondary cold warmup system. Essentially for idle conditions, the amount of airflow is a fixed amount and is adjustable only by turning the idle speed screw.

As you stated, car systems typically have a similar bypass circuit but with the addition of a computer-controlled pintle that moves to open or close the circuit, essentially automatically and very quickly adjusting the idle speed screw on the fly to keep idle speed steady (although typically it doesn't need to once it's learned the correct position). And as you mentioned, the computer will also pull or add timing (with RPM deviations as small as 25-50) to keep it rock steady at the commanded idle speed.

What's not known (by me at least) is whether the FZ6's computer is capable of adjusting idle timing to help smooth things out, which would cause idle "hunting" or loping if it's constantly missing it's target RPM. I suspect there is no such functionality however, because without the ECU commanding the idle speed (as in a car with a controlled idle air flow), the idle RPM is determined solely by the idle speed screw, and the ECU has no way of knowing what that speed is supposed to be. The ideal idle speed is also quite a large range which seems to point to the same thing: timing isn't adjusted on the flow.

So, with a fixed airflow and fixed timing, the real reason for loping idle is that the throttle bodies are out of synch. The idle speed air circuit allows a fixed amount of air flow in, but it's the "throttle body synchronization" (which is now a misnomer because it doesn't actually physically adjust the relating blade opening of each cylinder as with carbs) that makes sure each cylinder gets the exact amount of air; if they don't one power stroke will be more powerful than another, the stronger pulses increasing idle and the weaker pulses dropping the idle, in a mostly nice steady rythm.

Idle speed on fuel injected bikes is controlled by manipulating the throttle body to achieve whatever idle speed is chosen in the ecu. In cars ignition timing is varied as well (on a "quick" feedback loop while throttle position is used on a slow feedback loop. When you install a free flowing exhaust, the reduction in back pressure causes the bike to hunt and overshoot on idle. I'm
Not sure if bike tuning software has this function but increasing the idle speed generally works well to stabilize the idle on turbo'd cars and could help fix the problem. Or just live
With the loping idle cause it sounds pretty damn sweet!
 

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FastAss
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+1 on the TPS issue.

It took 4 trips to the stealership, collaboration of the FZ6 forum, and a report from the NHSTA before mine got resolved. (Sept. 04)

I have to say that after that, the FZ6 idled at 1200rpm until I got rid of it last week.
 
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