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Low idle / Fueling issue
19 posts · Started by Bink · 29 Jan 2010
Post 2 by ktmguy,
#2Could be all sorts of things mate!
Start with Lowrance's advise and check for water in the big connector near the radiator thank.
Some other suggestions
Cracked hoses that bleed air like on the SAS and to the map sensores?
Second butterflies closing? Balancing the cilinders could help...
Soo many things...
Start with Lowrance's advise and check for water in the big connector near the radiator thank.
Some other suggestions
Cracked hoses that bleed air like on the SAS and to the map sensores?
Second butterflies closing? Balancing the cilinders could help...
Soo many things...
Post 3 by Lowrance,
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Post 4 by Bink,
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Post 5 by Lowrance,
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Post 6 by Bink,
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Post 7 by ktmguy,
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Post 8 by smoky,
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Post 9 by Bink,
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Post 10 by Bink,
#10Thanks Lads, not much time available to do all the checks but will get back to you all when I do.
In the mean time I have added some to the unleaded - it might just make (some) difference?
Thought I might as well try it seeing that I won't have a chance to go through the troubleshooting steps any day soon.
In the mean time I have added some to the unleaded - it might just make (some) difference?
Thought I might as well try it seeing that I won't have a chance to go through the troubleshooting steps any day soon.
Post 11 by Bink,
#11Well folks I've managed to make progress.
I took the Throttle Bodies (TBs) off the boots but left them connected to the wiring & throttle cables. (did not dare to go as far as that)
They were clearly in need of a clean – I cleaned them while still in the air box and they look much better now.
Also checked the vacuum hoses and all seem fine.
Since then the idle has become much more convincing and consistent - happily sits strongly at 1400rpm now.
I did the ECU reset the next day during my lunch break - bike stalled 5m15s into the run - restarted and completed the 15mins.
Current status:
She still drops the idle to 1000rpm when closing the throttle & clutching-in while coming to a stop but now returns much quicker back to 1400rpm (both in neutral or clutch/1st gear engaged).
Stalling still happens but is more abrupt i.e. stalls @1400rpm rather than idle speed dropping off and then stalling. Restarts straight away no issue when pressing the starter button.
Also noticed hesitation (Hic up) @ idle.
I am still running the STP Fuel Treatment - another 2 tanks to go through to complete the bottle. Not sure if it has any impact but probably doesn’t do any harm.
What’s next?
Going by the above I do think the issue is down to a breathing issue. (caused by dirt?) When closing the throttle the valves close and cause the idle to drop below 1400 before re-adjusting.
As I did not take the TB out fully, could I have missed some of the bypass passages while cleaning? ()
Are these any bypasses on these TBs? I can’t see any on the Workshop Manual diagrams.
What else could cause an abrupt stall?
I think I am on the right path but as I’m not a mechanic know too little to know what I am doing right or wrong.
Thanks again…
I took the Throttle Bodies (TBs) off the boots but left them connected to the wiring & throttle cables. (did not dare to go as far as that)
They were clearly in need of a clean – I cleaned them while still in the air box and they look much better now.
Also checked the vacuum hoses and all seem fine.
Since then the idle has become much more convincing and consistent - happily sits strongly at 1400rpm now.
I did the ECU reset the next day during my lunch break - bike stalled 5m15s into the run - restarted and completed the 15mins.
Current status:
She still drops the idle to 1000rpm when closing the throttle & clutching-in while coming to a stop but now returns much quicker back to 1400rpm (both in neutral or clutch/1st gear engaged).
Stalling still happens but is more abrupt i.e. stalls @1400rpm rather than idle speed dropping off and then stalling. Restarts straight away no issue when pressing the starter button.
Also noticed hesitation (Hic up) @ idle.
I am still running the STP Fuel Treatment - another 2 tanks to go through to complete the bottle. Not sure if it has any impact but probably doesn’t do any harm.
What’s next?
Going by the above I do think the issue is down to a breathing issue. (caused by dirt?) When closing the throttle the valves close and cause the idle to drop below 1400 before re-adjusting.
As I did not take the TB out fully, could I have missed some of the bypass passages while cleaning? ()
Are these any bypasses on these TBs? I can’t see any on the Workshop Manual diagrams.
What else could cause an abrupt stall?
I think I am on the right path but as I’m not a mechanic know too little to know what I am doing right or wrong.
Thanks again…
Post 12 by Bink,
#12Hi Bink, The bike's ECU should throw a fault code, I suspect it is not. By chance did you ask the mechanic that performed the service to take a look or what he thought of this problem? I am not the most attentive reader but have you balanced your TB's yet? If your SD is totally stock you have quite a few vacuum lines that could possibly cause this symptom, I would try a can of WD-40 with the spray straw installed on the nozzle and while the bike is at a steady idle spray as many vacuum line connectors and all intake surfaces, if the idle raises when you spray a particular place, this would indicate you have a vacuum leak. I think that motorcycle shops are equipped with a harmless smoke tool/device that works a little better than the WD-40 method, simply because it can be tested when engine is shut down. They close the valves on one cylinder at a time and fill the cavity with this smoke, any leaks will piss the smoke out revealing the leak. By reading the explanation, I gather when your bike was in storage was it in the weather?
Post 13 by Bink,
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Post 14 by Lowrance,
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Post 15 by Bink,
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Post 16 by Bink,
#16Just did the TPS check.
Found that the front TPS (black connector) was showing 0.75v at closed throttle & 3.66v at full open.
Made some adjustments and the front TPS (black connector) was showing 0.64v at closed throttle & 3.51v at full open.
Did the 15min idle and she sits and idles fine.
After the ECU reset I started the bike up again and she went up to 3000rpm, before dropping back down to 1500rpm. When I run the engine and I hold the revs at say a steady 3000rpm all seems OK but when i increase the throttle at 3500 or 4000rpm the revs start to 'bounce' up and down. (~500rpm up/down)
Went for a short test ride and the symptoms are the same plus it doesn't drop the revs below 3000rpm when I close the throttle in gear.
So went back to the house.
Why is it that when the TPS is within the parameters I still have this problem.
The rear was spot on at the first reading but now I do not get a open throttle reading (both 2nd valves do respond to throttle openings) -
Rear TPS at closed throttle is now 0.98 - no open reading.
Front TPS at closed throttle is now 0.64 - open reading 3.51v.
Any ideas?
Found that the front TPS (black connector) was showing 0.75v at closed throttle & 3.66v at full open.
Made some adjustments and the front TPS (black connector) was showing 0.64v at closed throttle & 3.51v at full open.
Did the 15min idle and she sits and idles fine.
After the ECU reset I started the bike up again and she went up to 3000rpm, before dropping back down to 1500rpm. When I run the engine and I hold the revs at say a steady 3000rpm all seems OK but when i increase the throttle at 3500 or 4000rpm the revs start to 'bounce' up and down. (~500rpm up/down)
Went for a short test ride and the symptoms are the same plus it doesn't drop the revs below 3000rpm when I close the throttle in gear.
So went back to the house.
Why is it that when the TPS is within the parameters I still have this problem.
The rear was spot on at the first reading but now I do not get a open throttle reading (both 2nd valves do respond to throttle openings) -
Rear TPS at closed throttle is now 0.98 - no open reading.
Front TPS at closed throttle is now 0.64 - open reading 3.51v.
Any ideas?
Post 17 by Lowrance,
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Post 18 by Bink,
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Post 19 by Bink,
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