2004 VStrom 650 Cold Start Issue

[ehaughn]

I have been trouble shooting a fast idle issue on my 2004 vstrom 650.
Basically, when cold, it does not idle fast.  When the bike it warm its fine.
There is a fast idle screw, but I noticed if I change this setting, the TPS gets changed as well.
Which leads me to the question, is there a sequence order when making any changes on the bike?

STV (Secondary Throttle Valve) synchronization
TPS (Throttle Positioning Sensor) adjustment
STP (Secondary Throttle Positioning) sensor adjustment
Fast idle (bike cold) adjustment
Slow idle (bike warm) adjustment

On page 5-31 of the service manual, it provides a way to adjust the fast idle. This is done by measuring voltage from the TP sensor (P/W and B/Br) wires while turning the screw. BTW, the manual is wrong, it states between Red and B/Br. I adjusted the screw until the TPS measured exactly 1.21 volts.

But, after making that change, the TPS now shows the dash-line on the C in the dealer mode, is on the top and not middle.

I measure the voltage range of the dash in the middle of the C in dealer mode with the STV valves are fully open

Low is 1.075 volts
High is 1.161 volts

The spec is for the fast idle is 1.21 volts

Which as you can see, the dash with the C, will never align.

Maybe the voltage should be 1.12?


HELP

[mr_diver]

650cc K4-K6- there isn't a fast idle screw, just normal idle screw, LHS in the triangular engine mount section.

Adjusting that when cold will throw out the idle when warm - you need to adjust it when the engine is warm... 3 bars on the dashboard.

The fast idle is controlled by the ECU and secondary throttle butterflies with the STVA. - Don't mess with the STVA. - they can gum up... WD40 and cycle the ignition lots.

If you're messing with the idle speed when cold, it's likely the engine speed is too high when warm and this is taking the revs out of the normal idling range.
As the revs rise past the normal idle speed range the TPS is meant to increase. (Don't mess with the TPS unless you have too, they can go bad, but it's fairly rare and any adjustments must be don't with the engine warm as you have to measure and set when the revs are stable and not in fast idle. - Ask me how I know this!)

The problem you now have is you have adjusted the idle speed and TPS.
the idle speed need to be set and stable when warm before doing anything with the TPS, if you adjust the idle speed when the TPS is incorrectly set you will throw the whole lot out of sync and it's an awful lot of trial and error adjustments to get right again.

[ehaughn]

Hello mr_diver

Based on the manual, there is a fast idle adjustment.  Its on the front left hand side.  The ECU controls the STVA, which opens the STV plates fully, the connecting arm then slightly opens the throttle plates.

In my case, I noticed the fast idle screw was barely, so the fast idle was not opening the throttle plates.

Hope this makes sense.

[mr_diver]

What's the ambient air temp where you live when the fast idle isn't working?

I removed the secondary throttle butterflies and never had issues with it starting even in cold -5 celsius temperatures.
The ecu will take an air temp reading and decide if fast idle is needed, it will then cancel the fast idle when the water is up to temp.
It won't care about the water temp if the air temp is fine to run without the fast idle.
Most of the time here in the UK my bike didn't fast idle even before I removed the secondary throttle plates.

Though if you are trying to measure the TPS while the bike is in idling faster than 1500rpm you will likely seeing an out of normal range TPS reading as you're out of the normal idle speed range this. TPS readings only make sense when the engine is warm and in the correct slow idle range. (It was common to up the slow idle speed to around 1500 rpm for better starting and control at slow speed, but it buggers the TPS over time keep the regular idle speed 1100-1300)

With that fast idle screw, why not turn it up a little and when cold out see where it idles - why mess around with the TPS and other idle speeds if there was nothing wrong with them?
Adjust one thing, see how it goes, don't mess with multiple things at once - it'll just come back top bite you.

[ehaughn]

Thanks for the response.

I have adjusted the fast idle screw.  Unfortunately, it changes the TPS and makes it out of range, where the dash is not in the middle of the 'C'.

The manual also states about the voltage being 1.21 volts, but I cannot set the TPS to this ever.

[ehaughn]

Here is an update. I have set the warm idle to 1,350 RPM. All the sensors check out fine.

I ran the bike and it appears the STV is functioning fine. When cold, its wide open, when warm its mostly closed.

I need to adjust the fast idle as when I start it, its at 2500, but quickly drops after a few seconds.

Here is my question, it appears the fast idle drops after say 10 seconds. This seems very quick especially since the bike is cold when started. I see the STV starts to close.

Any thoughts on why it would close in a short time? Manual says the fast idle cancels between 104 to 122F.

[Rixington43]

BBC shows it's currently around 13C in Atlanta so not super cold, I wouldn't be surprised if the fast idle drops back quite quickly in those temperatures so I'd just adjust so the fast idle hits the target from your service manual and see how it behaves when the temperature drops.
Do you suffer with the bike stalling easily or running rough when first started? Does the temp guage show bars really quickly?

For reference, My K7 Vee had an issue of the fast idle not kicking in at all and the bike would stall really easily for the first 10mins of every ride.
The fast idle now behaves as follows;
Kicks in every time I start the bike but usually drops back within 30 seconds or so on all but the coldest days.
The Vee has a more comprehensive table for fast idle behaviour in the manual so I followed these guidelines and I now get about 2k in winter and the revs drop back to 1,700 and then 1,500 as the bars on the temp guage appear. Normal hot idle after a few minutes riding.
I don't ride in sub zero so I've no idea what it does then

[ehaughn]

I made an idle adjustment to 1350 when warm.  I will need to start the bike again today and check the RPM when cold.  I will also check the temperature and adjust to the manual.

Bike ran rough when I first started, had to turn up the warm idle.

It takes minutes, maybe 5 before 1 or 2 bars show.  I will check this as well.

My manual states 1500 to 2000.  It cancels once temperature reaches 104 to 122.

Should I use your guide to adjust the fast idle?  Or should I just target between 1500 and 2000?  If I target the 1500 to 2000, what RPM do you suggest?

[Rixington43]

I would use your manual since the ECU behaviour may be different, I just referred that table as an example for the change based on ambient.
I would personally aim for the higher end and just make sure your warm idle is unchanged once the bike is up to temperature. A higher fast issue will help cold running and get the bike up to temp quicker.

[Rixington43]

Sorry if I missed it but, have you done secondary and primary throttle sync and checked for any vacuum leaks.
Mine also ran rough at idle when I bought it and it turned out the throttle bodies were out of sync and failed vacuum take off bungs were making it impossible to get a good balance and therefore a good idle.

[ehaughn]

I have not done the primary throttle sync yet.

I have attempted to on the secondary throttle, but found it difficult to measure.  The slightest would throw off both readings on front and back.  Unless there is some trick to this.

I do not believe I have any air leaks.

[ehaughn]

A few updates.

Outside temperature 57 F
Fast idle set at 2,000 RPM

Started fine, ran at 2,000 RPM for about 1 min 12 seconds

Temperature gauge running at idle
1 bar took 3 mins 18 seconds to display
2 bars took 6mins 51 seconds to display
3 bars took 11 mins 57 seconds to display

I then turned off the bike

Tomorrow I will do another cold start and measure the RPM and duration.

[Rixington43]

For the secondary balance I pushed one throttle plate fully closed (The plates on my 07 move freely with the engine off, if yours don't then don't force them as I believe some earlier models are fixed). I measured the distance from the top of the throttle body to the plate with a depth guage and then held the plate closed whilst I set the other to match. Anywhere close is fine I believe so, if you've tried and got close, good enough.

I would suggest a primary balance though, it might be fine but, if they're out then a balance will dramatically improve idling when cold.
Fingers crossed you're all good on your next test run.
Looks like your temp guage is all good though so hopefully it's just getting the fast idle cam position right and you're sorted.