St1300 idle tick over problem

[easy rider]

Hi Everyone Happy new year!

Well here we are again my recent purchase in October of my ST1300 A9 2011 with only 18500 miles on the clock has slowly started to develop an idle problem which has now got to the point where it does it every time I Start from cold or after a ride then parking and coming back to it after it starts to cool.

I started to notice it starting to stumble and stutter and it played up for a few days then was fine for 3 weeks then when i finished work for Christmas and its not been used as much it started playing up again.

No fast idle at start up though it does if your lucky but its rough and then drops to below a 1000 rpm.
sometime stall and continues to stall unless you help with the throttle.

I now have to use the throttle on start up and eventually it corrects and holds idle once warmed up.

I started getting a slight stumble and stutter to the idle.
Been out for a blast on her today and at highway speeds it great runs smooth power forward no issues and when stopping at the lights holds idle fine.
Got back home went out to it later same again won't hold idle have to use the throttle until warms up and corrects.

If you leave it to idle rough it sometimes just corrects after a few minutes as if a switch was flicked.

Bike has had a service since I bought it.

Changed oil & filter
shaft drive oil
brakes & clutch
air filter
new spark plugs to try and correct the slight stumble at idle
moved my ignition coils and leads from my old ST1300 as they were all new to rule that out
going to swap out my IAT señor also off my old bike as that was new also.

It's in at the garage Saturday so will see if they can do the following as i am back in work next week and time is something i don't have to work on it.

check 5 way T and replace vac hoses as i have a spare rubber hose that is new in my work shop
Throttle body sync can't hurt either i guess

Since i bought the bike it was great though i did find some issues with a parasitic draw on power causing the battery to drop enough to cause hard starting and wipe the clock and trip settings which was due to a Tom Tom Sat nav cradle they had mounted above the dash which was wired into the back of the loom that goes to the dashboard clocks.
The oxford grips were also wired into the position lights which was also causing problems and the grip heaters were not getting enough power.

I removed both of theses problems and now it no longer has battery problems and to be double sure I had a spare brand new front loom that i never used on my old ST1300 so i replaced this which removed the loom where they had spliced in to add heated grips and sat nav.

The idle issue is a worry as i really hoped I was going to finally have a bike that works as my other ST1300 was getting old and maintenance was getting higher and costly so i am just using it for parts many of which were new.

Some of you may remember I had to take it off road due to u joint which cannot be replaced due to swing arm being stuck.

The other problem i found with my new ST1300 was the quartet harness connector on the main loom does not work either as i had just bought a quartet harness to add my sat navigation to and after checking the connector i found that the wires were broken at the connector so that also needs fixing.

I think the throttle body sync and 5 way are a good place to start.

Fingers crossed we work it out but if anyone has any ideas please let me know, though to be fair been here before with this in the past.

St1300 is an amazing bike but sure can be pain when it wants and I guess although this has low milage its still 13 years old.

will check fuse tank breather hose as well.

 

[Andrew Shadow]

Fast idle is controlled by the SE thermal valve, commonly called the wax valve. It could be a defective valve but it can also just be that the linkage is binding preventing the starter valves from moving and preventing a fast idle.

 

[easy rider]

Thanks Went to start it late last night when it was cold and it started and fast file fine which must be because I had taken it out for a long run. Will get the linkage checked and hair dryer on wax valve to check its operation
It’s just back to the old process of elimination I guess hopefully find fix quickly.

It must be because the previous owners have not used it much with the low mileage over 13 years.


Started normal just now first start of the day fast idle to 2000rpm then drops to 1000rpm and holding. Temperature outside 3 degrees
Tick over sounds fine no stuttering

 

[diferg]

do you have cruise control? They oftentimes develop vacuum leaks and problems like you describe. temperature seems to play a role in the severity of the symptoms. I removed my cruise control and gave it to a friend! If you dont have cruise control disregard this reply.

 

[Igofar]

Did you replace the vacuum hose with 4mm hose?
There are a couple aftermarket companies selling hose advertised as such, but are not correct, and are to large causing vacuum leaks.
In 17 years I’ve never found a defective idle wax valve, but what I often find is the threaded rod that goes through the black plastic barrel, that sits loosely in the two hook type arms, dirty, and the threads catching on the edge of the hole, causing it to sometimes stick causing issues like your having.
The first hose is the bad one.
The Prestone is correct size.
See picture, prestone hose on right side.
Last picture, spray/clean barrel with plastic safe contact cleaner.

 

[easy rider]

Did you replace the vacuum hose with 4mm hose?
There are a couple aftermarket companies selling hose advertised as such, but are not correct, and are to large causing vacuum leaks.
In 17 years I’ve never found a defective idle wax valve, but what I often find is the threaded rod that goes through the black plastic barrel, that sits loosely in the two hook type arms, dirty, and the threads catching on the edge of the hole, causing it to sometimes stick causing issues like your having.
The first hose is the bad one.
The Prestone is correct size.
See picture, prestone hose on right side.
Last picture, spray/clean barrel with plastic safe contact cleaner.

Hi
There is no cruise control fitted on the bike, i started her up again today to ride over to my garage so i could update them on work I want carried out this Saturday and it started but engine tick over stumbled three times enough to jolt the bike , kind of like an interruption then it smoothed out again.

Once on the highway rides like a dream as it should with only very low mileage with no interruptions or anything.

I always knew picking up a second hand bike was going to be risky its low milage but its still 13 years old so not been used much really since it was registered in 2011 but once i stripped her down and had a look around i already found mistakes like with the sat nav wired into the loom at the back of the clocks which was causing the parasitic draw on the battery.

Not sure if low voltage issues could have effected sensors or the fact it's been not used much dusty or dirty it been sitting around since 2021

So i have so far myself fitted -

New battery
replaced front loom for lights horn screen temp sensor ect. ( was not happy with how they went into the loom)
Moved over my new ignition coils and leads from my old ST1300 which was no cost.
new spark plugs
removed side light loom and put new one in, had a spare as they had oxford heated grips running off this which was struggling with low voltage so grips don't get that hot with constant low voltage. they are now fitted direct to the battery and work much better, may fit into quartet later.
Replaced Air filter
All the usual fluid changes all done.

On Saturday we will start with replacing vac hoses with new hose make sure the 5 way t is clear and sync throttle bodies because looking at service history it's never been done so can't hurt.

Vac hose I have in my workshop is Bulk vac hose from CMSL in Holland which is ordered off the schematics for the model and year of bike with all Honda parts and alternative parts if not Honda. I used this hose on my old ST1300 also still have loads left as it was a bulk roll of hose.
Thanks though you'r right you have to be carful when buying as a bad fit can cause even more issues.

I agree with you on the wax valve not convinced its that plus i changed one of them on my old St1300 and it was never the same after as nobody could get it dialled in correctly so it was fast idling really high. The bike is perfect when it works even in the cold 2000 rpm gently drops to 1000rpm when the first bar lights up on the temperature bar so set perfectly not messing with that confident its working fine.

I did however change the IAT sensor out today after i got back from the garage as the one on my old St1300 was also new last year and since swapping it out after testing it seems to have improved idle so we will see how it is.
Not getting too excited as its not the first time these bikes have played ball then when you least expect act up again.

Its handy having the old Pan on hand for parts swaps i might take the fuel pump off it and put it away as that was also replaced at 120,000 miles with a new Honda one bike bike kept cutting out with low fuel pump would overheat then once it cooled started up again, bike was taken off road October 2024 at 136,000 miles.

The wires on the top box spoiler tail light on my new bike are also a bit dodgy where the previous owner wired into the main taillight in line with Honda kit but it keeps cutting out the spoiler brake light when the wire moves so for now i have secured it with zip ties so it does not move, main brake lights are fine.
There are broken wires on the quartet harness connector on the main loom tucked away behind the radiator will get that fixed Saturday also as i want to plug my sat nav and my Honda radio into the new quartet i bought.

The idle was really bad yesterday it would just not hold and kept stalling needed a hand with the throttle
I don't like it when it stumbles its like it misses a beat on tick over and jolts.

This bike was fine for weeks when i bought it early October then slowly started with the odd stumble missing beat or two then got worse.
Replaced spark plugs and air filter then it was fine for a few weeks but then when i finished for Christmas it's not been used much and then started going wrong again.

Going to blow out the fuel tank breather also just in case.
To be fair under the air box is the only place we have not looked at yet on this bike so who knows what we will find!

I will keep you all updated on how it goes I hope once i have ironed out the issues it will be a good bike because it is in really good condition its just it had only done about 2000 miles between may 2019 and when i bought it October 2024 so really not been used much which may have contributed to it acting up.

Best wishes

Martin

 

[Andrew Shadow]

Started normal just now first start of the day fast idle to 2000rpm then drops to 1000rpm and holding.

Saturday and it started but engine tick over stumbled three times enough to jolt the bike , kind of like an interruption then it smoothed out again.

Sometimes working normally and sometimes not is why I suggested the below. When the linkage does not bind or catch it works fine. When it does bind or catch it does not. Checking the linkage can't hurt either way and it cost nothing (If you do it yourself).

it can also just be that the linkage is binding preventing the starter valves from moving and preventing a fast idle.

 

[easy rider]

Sometimes working normally and sometimes not is why I suggested the below. When the linkage does not bind or catch it works fine. When it does bind or catch it does not. Checking the linkage can't hurt either way and it cost nothing (If you do it yourself).

Agreed will check it also definitely not disregarding I think it’s a case of work through everything stage by stage.

Just checked it now and it started perfectly idle seems smoother and positive. Dropped to 1000rpm held solid. The stutter has gone also.
This is after swapping out IAT sensor it’s like a different bike compared to the last two days.
Will see how it goes need a few more starts before I can call it but It’s going to the garage as I am back in work so don’t get much time.

I appreciate all help

Best wishes

Martin

 

[Andrew Shadow]

I understood that it was intermittently not achieving a cold start fast idle RPM. Cold start fast idle RPM is initiated by the SE thermal valve. With a defective IAT I would expect a rougher running cold engine and a fast idle that is unstable. It should still achieve a cold start fast idle however because of the SE thermal valve.

If the IAT does turns out to be the fix do let us know.

 

[easy rider]

I understood that it was intermittently not achieving a cold start fast idle RPM. Cold start fast idle RPM is initiated by the SE thermal valve. With a defective IAT I would expect a rougher running cold engine and a fast idle that is unstable. It should still achieve a cold start fast idle however because of the SE thermal valve.

If the IAT does turns out to be the fix do let us know.

Yes will keep you all updated, started it again this morning and it started up fine again 2000 rpm nice and smooth dropped idle slowly to 1000 rpm held solid no stutter, its like a different bike the last few days its been running consistently rough at start up and even after taking it out for a blast then coming home and going back to it after it was still rough.
When started you could not ride off straight away as it would stall the minute you dropped to idle at traffic lights so had to wait for her to settle. Since the IAT was replaced yesterday it seems to have helped because the last few days it was becoming a constant at every start up.
I wonder when i got the bike in October its not been used much last 3 years i use it and slowly it starts to get worse i have idle issues then we service it replace plugs air filter and it seems ok then it goes down hill again. I hope its the IAT stranger things have happened could be the sensor was dirty form being left or the constant low voltage due to parasitic draw upsetting electrics that I found and looking at the service history its last service was three years ago and the filter was bad with dead bug found in the box stuck half way between the air filter base, how that got in there i don't know. the issue started after a month of riding then went away for three weeks after service then the last three days it was consistent rough starts no idle and stalling with each start up with occasional shake and stutter at idle. will see how it goes and get the throttle body inspected new hoses check the 5 way and sync throttle body then keep fingers crossed.
Thanks so much for your help as always going to take her out for a spin in a bit see how it is. I know all too well with my old ST1300 just when you think you fixed your idle issue it comes back at any random point, I also know when heating and cooling the bike the goo in the 5 way if present can move which can alter how it acts on different starts if that is the issue.
Thing is with the 5 way bike is cold goo sets bike heats up goo melts so i would not expect it to have issue when warm like it does though depends on how its blocked i guess.
I have two spare map sensors and new Idle air control valve in my workshop also but will leave that for now see how it goes. I am sure we will get there eventually hopefully quicker this time, my old ST1300 ran like that every winter for two years only when cold weather though but it was combination of blocked T and hoses plus throttle body boots were hard and cracked but with this bike temperature seems to have no specific bearing on it as it was doing it at warm or cold temperature so sensor could be a fault we will see.

I had another ST1300 years ago that had constant over fuel spark plugs would be knackered within a ride and it would buck and cut out also idle was rough and stalling, dealer replaced all sorts wire loom, coils leads nothing worked and thankfully it was under warranty. it ended up being the TPS sensor on the throttle body that was the issue bike would cut out when riding at random points which was scary and was running really bad when out riding normal. never showed any codes what so ever for that which is the problem you can have a faulty sensor and it won't tell you due to what the parameters they allow before it tells you its not happy which is a pain.

Will take this stage by stage and see what changes.

Best wishes Martin

 

[easy rider]

Well its been running fine since the 3rd January and i did not want to tempt fate but sure enough and true to form started to stutter when leaving work this evening.
Something to note is the temperatures have been at between 2 degrees c and - 4 degrees c with a fast idle of 1900rpm over the last week with really cold weather.

Today it was 3 degrees c 1900 rpm no stutters warmed up to 1000 rpm.
Tonight 8 degrees c outside temperature been sitting all day starts with a lower 1500 rpm fast idle sounded out and stuttering then the engine was interrupted as if it was stopping then went back to normal tick over.
I was kind of waiting for it to do this as i know all to well it may well start some of the time but when you least expect it the ST1300 can start to go wrong again.

that the thing with these bikes they can have a fault but it will still run most of the time with just a niggle.

So i guess the next step is to look at throttle body sync, New vac hoses and check 5 way T is clear and take it from there.
The thing with the 5 way i know form before with my old bike that temperature can effect how the gunk is in the lines when its hot or cold. Strange thing is my old bike it was always effected by cold weather this is different.

We didn't do anything else to it after i swapped out the sensor wanted to see how it would run before doing anything else.

Will update

 

[Fawlty]

Maybe check the thermostat? Also may be worth making sure your radiator is not silted up. Could be a cooling system problem.

 

[easy rider]

Maybe check the thermostat? Also may be worth making sure your radiator is not silted up. Could be a cooling system problem.

Just gone to check it now and the indicators were not working so disconnected the relay and reconnected and they are back on. but that's the second time the relay has done that so just wondering if that is causing my stutter as its electrical. funny how it played up this evening with rough stutter and then i check it again now and the indicators play up again though its probably just another issue among issues with this bike. Going to order another relay as its happened twice now you unplug it and plug it back in and indicators are back on. With you on the radiator though it has had a coolant flush since i bought it along with everything else all fluids plugs coils & leads. I do know if the thermostat is dodgy it sticks open so the at highway speeds you would end up with decreasing temperature and no bars on the temperature gauge due to cold air flowing through the radiator at high speeds.

 

[Andrew Shadow]

If I haven't misremembered the problem is on start-up before the engine warms up. Conditions like a defective thermostat or radiator would affect the engine once it has warmed up but not when it is first started cold.

 

[easy rider]

temperature was 3 degrees this morning started went to work then after sitting all day temperature outside was 8 degrees c started but with rough low fast idle. then when i got home and it was left for a few hours it then started really rough and stalled would not tick over had to open throttle to increase rpm then it held idle but dropped. opened full tank briefly then closed it and started and it seemed better.
I am going to check tank breather hoses from lower and upper tank just in case with it being a bike that has not been used much. But does seem now the weather has warmed up its struggling. once you get going its ok

 

[easy rider]

I don’t think it’s the breather hose
All I know is now the weather has increased in temperature it’s not happy won’t idle so it’s a trip to the garage I think we need to check the throttle body

 

[Andrew Shadow]

I wonder if the ECM thinks that the engine and/or air temperature is warmer than it actually is so it does not fuel properly when at certain ambient temperatures, or if the SE thermal valve is not properly reacting to the ambient temperature and is not commanding a fast idle.

Throttle body synch certainly won't hurt.
Did you ever check to make sure that the SE thermal valve linkage is free and not binding?

 

[easy rider]

I wonder if the ECM thinks that the engine and/or air temperature is warmer than it actually is so it does not fuel properly when at certain ambient temperatures, or if the SE thermal valve is not properly reacting to the ambient temperature and is not commanding a fast idle.

Throttle body synch certainly won't hurt.
Did you ever check to make sure that the SE thermal valve linkage is free and not binding?

No after the temperature sensor change wanted to see if that had worked first so it’s now time to go under the air box. Bike has been sitting over night and it’s 9 degrees started up slight fast idle down to first bar and 1000 rpm. Last night it would not run
its Nightmare really thought getting this bike would be the answer t my old bike and back to square one.

 

[Fawlty]

Just gone to check it now and the indicators were not working so disconnected the relay and reconnected and they are back on. but that's the second time the relay has done that so just wondering if that is causing my stutter as its electrical. funny how it played up this evening with rough stutter and then i check it again now and the indicators play up again though its probably just another issue among issues with this bike. Going to order another relay as its happened twice now you unplug it and plug it back in and indicators are back on. With you on the radiator though it has had a coolant flush since i bought it along with everything else all fluids plugs coils & leads. I do know if the thermostat is dodgy it sticks open so the at highway speeds you would end up with decreasing temperature and no bars on the temperature gauge due to cold air flowing through the radiator at high speeds.

OK. I assume you don't get the three bar to two bar dance on the temp. gauge?
Have you tried the ECU reset procedure? Long shot but it may be worth a try. Nothing to lose.

ECU Reset | ST1300 Related

Has anyone else come across or indeed tried this? I have done a search here but cannot find any reference: 1.Completely disconnected the battery for 24h (my reading sources state 10 minutes to half an hour). 2.Turn the key to on to get rid of any held power for about 30 seconds...

www.st-owners.com

 

[MidLife]

temperature was 3 degrees this morning started went to work then after sitting all day temperature outside was 8 degrees c started but with rough low fast idle. then when i got home and it was left for a few hours it then started really rough and stalled would not tick over had to open throttle to increase rpm then it held idle but dropped. opened full tank briefly then closed it and started and it seemed better.
I am going to check tank breather hoses from lower and upper tank just in case with it being a bike that has not been used much. But does seem now the weather has warmed up its struggling. once you get going its ok

Is it stalling at idle only, fine when opening up the throttle?