Suzuki GSX-R Motorcycle Forums Gixxer.com banner

1 - 14 of 14 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
Hi I have a gsxr 1000 L2 and have a misfire after 9k but only when throttle is pulled back fast, if I gently pull throttle back all the way the bike don’t misfire at any rev but if then I let off and then pull the throttle back fast it misfires but if I’m under 9k I can pull the throttle back on and off really quick and it won’t misfire, any idea please
 

·
I know things... A lot of things.
Joined
·
3,093 Posts
Define misfire more precisely. For instance, if it's a bogging/stuttering/hesitation, a fuel flow test would probably be in order. The service manual has all the details.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #3
Hi yeah it really feels like a misfire but only does it if I twist throttle fast and after 9k so riding on normal roads I can twist throttle back fast and bike pulls like it should but on ring roads I got to ease it to full throttle then it don’t happen
 

·
Registered
Joined
·
9 Posts
Discussion Starter #4
Also I managed to get a whole fuel pump assembly brand new very cheap and it’s fitted to bike and still does the same plus I swapped the injectors round think it might do the opposite like misfire at lower rev but also still no different
 

·
I know things... A lot of things.
Joined
·
3,093 Posts
So you can still go WOT, at high engine speed, just not too suddenly? I wonder if your TPS is worn feeding spurious inputs into the ECU if you twist the throttle too fast. I wouldn't expect that to have happened on such a relatively new bike, but still, it might also fir with your "happens only above 9k rpm symptom", since I believe that the ECU fuels based on TPS and engine speed only at higher loads. Perhaps you might want to try to disconnect the TPS and see if it makes the problem go away, or at least changes significantly in character. If you try that, note the following:

1. Please exercise all due caution, as I haven't ever ridden without a TPS and am not sure how it would behave. Make sure you ride conservatively, in a safe environment and no longer than necessary for the purposes of troubleshooting.
2. With the TPS disconnected, fueling will be calculated based on the IAPS. At near-WOT and hence near-zero vacuum the IAPS' reading will be rather inexact, so expect potentially choppy operation at near-WOT and concentrate on whether the problem is the same in character during fast opening or not.
3. Again, be careful.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #6
Yeah she will rev all the way to redline only on steady twist of throttle, it’s only past 8 or 9k I can’t twist throttle back fast or it will miss or splutter enough not to climb rpm, I do most work to my bike but must admit I’m rubbish with how the electrical side of things work or behave so your advice is truly appreciated and I will try what you suggested with the cautions you said about thanks, I’ll report back my finding
 

·
I know things... A lot of things.
Joined
·
3,093 Posts
Regarding redlining, note the following: usually such bogging issues are due to fuel starvation, with the most common cause being a clogged fuel filter, usually due to bad gas. Now the fuel requirements at a certain operating point of the engine basically depend on both engine speed and throttle opening (as the latter roughly determines the fuel demands per cycle and the former the cycles per minute). So redlining doesn't mean much. It's one thing to redline the engine in neutral for instance where it only has to pull its own weight, requiring a relatively small throttle opening, and another to redline it in sixth.

So say if, starting with idle speed and a suitable gear, you can open the throttle to WOT relatively smoothly and the engine will pull through to red line at WOT (even though you've reached WOT before passing the 7-8000 rpm mark say, then your problem is likely not due to fuel starvation. If on the other hand, you can redline the engine in lower gears by not going WOT, but not if you're at WOT inside the power band, then a fuel starvation is quite likely.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #8
So say I’m in second gear from 3k revs and now wack It back to full throttle and keep it there it will climb rpm as it should and will hit redline but then if I let off and straight back on full throttle fast it will then misfire or splutter, would that be fuel starvation
 

·
I know things... A lot of things.
Joined
·
3,093 Posts
No, if you whack it open at 3000 rpm and it can climb past the power band and up to redline with the throttle held wide open, then you shouldn't have a fueling problem. (There is one small caveat here: it is quite likely that the ECU increases the fuel to the engine when it detects the throttle being whacked open. The reason is that air is lighter than fuel and will arrive faster, so the extra fuel is meant to prevent a lean condition from developing. Now if your filter is clogged just enough it might have trouble only when you whack it open while crossing the power band, or something like that, so it would still be best to measure how much fuel the pump discharges per 10 seconds, to properly rule it out.)
 

·
Registered
Joined
·
9 Posts
Discussion Starter #10
I disconnected the TPS plug like you advised and took it up the ring road and my problem has gone completely intact I nailed it in first and went in to second just before redline and the front wheel slightly lifted, I haven’t felt her so fast in a long time plus did all the on off throttle fast and my misfire I had before has gone so it has to be the TPS sensor at fault??
 

·
I know things... A lot of things.
Joined
·
3,093 Posts
so it has to be the TPS sensor at fault??
It does look that way. Now the question is whether it's a matter of replacement or adjustment. Try warming up the engine, adjusting idle if necessary based on what's specified in the service manual and, while it's idling, switching to dealer mode. You'll see a dash followed by C00 where the coolant temperature readout is. The dash should be centered. If it's at the top or bottom, you'll need to adjust the TPS.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #12
The line was in the middle so I purchased a new TPS sensor and it’s a lot better now but still not perfect, my manual says once fitted and adjusted take to a dealer and get it learned, do you know what that is about?
 

·
I know things... A lot of things.
Joined
·
3,093 Posts
Note that it probably is important to adjust the TPS dash with the engine running and warmed up. If you haven't done so, it's probably off. On the newer models, such as yours the TPS can also be adjusted without manual rotation I believe, via the SDS. Check the service manual for more information. You'll probably have to take it to the dealer though (or purchase a used/knock-off SDS).
 
1 - 14 of 14 Posts
About this Discussion
13 Replies
2 Participants
scoodee17
Suzuki GSX-R Motorcycle Forums Gixxer.com
A forum community dedicated to the Suzuki GSX-R motorcycle. Discuss the GSX-R600, GSX-R750, GSX-R1000, and GSX-R1100, and more!
Full Forum Listing
Top