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Discussion Starter #1
Hi guys.
I have a 2008 suzuki gsxr600 k8.
I am currently experiencing some problems with acceleration.
My bike usually tops up to 16,000 rpm.
However, its been some weeks that it does not reach its maximum.
It reaches only 6000 rpm or 8000 rpm.
Occasionally, it may reach 14000 to 15000 but very rarely. It mostly stucks on 8000 rpm.


I have checked and clean the fuel pump, cleaned the injectors and used injector cleaner.

Battery was checked and stator as well, works perfectly.
Does NOT seem an electrical problem.

No error code appears on the speedometer.


Bike is still the same. Even today, it stuck nearly on 5000 rpm.

Might it be the throttle sensor giving that troubleshoot?

Anyone having experienced the same?
Any ideas please??

Junaydjkd
 

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Captain Obvious ... because obviously it’s obvious
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Do a fuel flow test.
 

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once you checked all the obvious ones (fuel line, sparks, etc...) a quick test is to disconnect the cables of the exhaust valve

in my case (due to a wrong job by my mechanic) exhaust valve not opening, with no FI error, caused me this exact behaviour: RPM stuck at 8.000
is not the most probable cause, but is so quick to make a test disconnecting cables that you would like to spend 5 minute on this, too
 

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Discussion Starter #5
once you checked all the obvious ones (fuel line, sparks, etc...) a quick test is to disconnect the cables of the exhaust valve

in my case (due to a wrong job by my mechanic) exhaust valve not opening, with no FI error, caused me this exact behaviour: RPM stuck at 8.000
is not the most probable cause, but is so quick to make a test disconnecting cables that you would like to spend 5 minute on this, too
Yes but mine has no cables in exhaust valve.
Has an aftermarket full line yoshimura on it.

Might be the throttle sensor??? (STPA)??
 

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it should throw an error, at least. anyway, just to be sure that the secondary throttle plates dont remain closed (the symptoms should be similar, also if as told i expected an FI becouse there is a check on each key ignition) is quite easy to do an empirycal test: lift tank, remove airbox.. and just disconnect the TPS sensor and the STVA, gently opening them manually and leaving them opened. turn the bike on, it will give you a couple of FI error, but you can give it a quick ride and check if RPM goes high normally

(on my 600 k6, due to a STVA failure, i've them fixed open, with FI error disabled via ecu reflash)
 

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Discussion Starter #7
Did that.
Unplugged the TPS sensor and opened the STVA manually. C29 code appeared.

It went up to 14000 rpm.

However, could not sustain that for long; if i keep the gas open maximum, it would fall back slightly to 10,000 and 8000 rpm.

Problem is that when both sensors are plugged, the rpm goes max to 6000 rpm.

Could it be the fuel pump startimg to default??


Really a headache!!!!
 

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i think you should try to understand if that "limitation" that occurred now, with stva and stp disconnected, is ecu-based.. or not
i mean... when is fuel, is not blocked always exactyl at the same rpm... sometime more, sometime less,. sometime in just goes rough... when instead is ecu-based, is quite easy to replicate it and individuate a precise rpm range where it ALWAYS get stuck.. always at the same conditions

now that im writing, i remeber that when i fried my rectifier, and got c-28 erorr (STVA troubles are quite common when rectifier fail, for some pin on ECU that get fried too), i disconnected STVA and put it open manually
then i remember that when i tried the bike at wide open throttle, me too i got RPM blocked at a certain amount.. maybe 8000 rpm too

i remember i had to reflash ecu to disable c-28 error, and all gone ok since then

im not tellingmyou to keep things disconnected an relfasg your ecu now, but im telli g that with these tests you should be able to understand if it is a "physical" limitation (not enough fuel... etc..) or an "electronic" limitation
the second one is much more easily replicable and give always same result (same exact rpm where it stucks, etc)

i think it could be something ecu-based, due to a faulty tps or stva, if you just said that with all discnnected it revved with no hesitations (if fuel pump has trouble delivering gas, you would have not be able to rev without esitations)


on one of my two k6 600, i've STVA disabled via ecu, exactly for a situation similar to this, but this is just anecdotal :(
 
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