Problems at Steady Throttle

[pete.jones]

Hi All
I'm struggling to resolve a problem with my bike, an '02 1150 single spark with 35K. After a particularly hot run in France last summer I've noticed that at a constant throttle above 2k rpm the bike will stutter / hesitate slightly as if missing a cycle, so holding for instance 30mph in second is an uncomfortable way to pass the time. It gets worse as the engine reaches operating temp. Open up the throttle and the bike pulls strongly and smoothly all the way to speeds that scare an old 40-something like me. If I hold the engine at 3k rpm in neutral I can hear the engine missing occasionally (every 2 - 3 seconds) so I don't think that it's the drivetrain. The bike does not surge and it starts well.


So, onto the things I've done:

- Valve clearance and float are set fine. TBs are balanced.
- Dealer tells me there are no fault codes logged. They changed the rubber seals on the TBs inlet manifolds as they were leaking slightly.They also gave the bike a full 36k service.
- TPS voltage is set correctly
- Meta immobiliser removed (was playing up)
- I've been through the loom with contact cleaner looking for bad connections. Fixed one bad connection to the air sensor, got excited but it's not fixed it.
- Cleaned injectors (showing a nice spray of fuel before and after)
- Tried a Remus can with Y-piece (and a 2nd hand sensor from Motorworks), no different (in respect of the problem). I've used gum to ensure that there are no leaks upstream of the sensor.
- Removed HIDs (straw and clutching I know..)
- I've run the bike for short periods with the air sensor and exhaust sensor disconnected but the behaiviour remains.
- I've tried the CCP mod and, although I like the effect this has, the behaiviour remains.
- Finally, I've run on the most expensive unleaded (V Power?) and added a little Redex injection cleaner but to no avail.

So, at this stage I'm up at the threshold of my limited knowledge and unsure how to continue. Would there be any value in getting the bike on a dyno - would this help me understand what's happening in the engine to cause this problem and then allow me to focus my efforts (or someone elses) in the right area? And if so, anyone happy to recommend anyone in the Kent / London region?

Thanks for reading fellas!

Pete

 

[Decster]

And if so, anyone happy to recommend anyone in the Kent / London region?

www.gsshop.co.uk

kingston, london

 

[Colban]

They also gave the bike a full 36k service.
Pete

Did they DEFINETLY change the plugs?.You haven't mentioned them.
Possible coil problem?.Maybe ignition hall sensors.
Have you cleaned/checked the connectors to those components.
Any water in the tank?.
Did the problem first occur after you had filled up with fuel in France?.

 

[Comfy Old Boots]

I had a similar problem, got the same but work done but additionally got the lambda sensor replaced. No surging anymore

 

[pete.jones]

Thanks for the input guys.
Yes, plugs definitley changed at service, I've also cleaned the connectors to the coil although not to the Hall sensors. I'll try this over the next couple of days. I'll also have the tank off and check for water. I've found no documented evidence of the fuel filter having been replaced so I'll do this too (I've read it's a b'stard of a job! .)

The first time I noticed was in France, almost certainly after filling up there...

cheers!

Pete

 

[Colban]

Thanks for the input guys.
Yes, plugs definitley changed at service, I've also cleaned the connectors to the coil although not to the Hall sensors. I'll try this over the next couple of days. I'll also have the tank off and check for water. I've found no documented evidence of the fuel filter having been replaced so I'll do this too (I've read it's a b'stard of a job! .)

The first time I noticed was in France, almost certainly after filling up there...

cheers!

Pete

BWM say change fuel filter at 24K miles.I did let mine run until 42K before changing it;but i didn't have a problem to fix.You can check for water while you've got the plate off.
The reason for the France comment was an incident a couple of years ago.
Filled up with sans plomb at a supermarket and all 3 bikes in the party started playing up,misfiring,smoking,pinking;all sorts of shite.
Suspected diesel in the fuel.Had to run 98 RON to clear it out.Maybe some residual fuel problem from then?.

 

[Spout]

I had a similar problem, got the same but work done but additionally got the lambda sensor replaced. No surging anymore

That's what cured mine.
Surging first started after I filled tank with cheap petrol.
After months trying to sort problem I eventually bit the bullet and plugged the bike into the dealers "box of tricks" - O2 sensor (lambda) error picked up.

Good luck.........

 

[junior]

steady throttle

Hi
Fuel fillter is not a bad job just remember to mark one nut and bolt on tank with felt pen so you put it back in the same place took me about 50 mins . Try some brisk spark plugs to.

 

[DrFarkoff]

fuel filter if you are goinf to change the filter and haven't done it before see if there's some one who has near you!

Fiddling with the drain pipes can be a right pain in the ????

and trying not to bend the fuel level arm! etc etc

My Biggest tip!!! Clean the end of the wee studs really really well with a wire brush and spray liberally with WD type stuff

Don't use contact cleaner of the connectors Use ACF50

The dealer should be able to display a realtime graph of the lamda and from this they can tell if it's fecked!