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Inconsistent idle

3K views 20 replies 5 participants last post by  jeeves 
#1 ·
A few weeks ago I noticed that my idle rpm's were going up and down a bit. The bike ran ok, but when going home from a trip the engine was not working properly under 4000rpm.

My first thought was that the TPS was acting up, so I put it in dealer mode and the C00 line would jump up around 3000rpm.

I also found out that the breather filter in the airbox was almost gone.


Cleaned out the airbox, put in a new air filter and still waiting for the breather filter.

Changed the TPS, sync'd the throttle body's, but the idle was still inconsistent. It starts when the engine is hot, 3 temperature bars.

The wierd thing is when I unplug the vacuum tube from the air pressure sensor the idle rpm's are then consistent and dead steady.

There are no vacuum leaks, new vacuum hose and caps.
There is nothing blocking the vacuum tube either (checked it).

Not getting a C13 error code.

The secondary throttle plates have been out for 10 years.
It looks like that for some reason the STA motor starts moving up and down trying to compensate for something and in the process also moves the primary throttle plates.

The idle speed has been inconsistent in the past as well when the engine gets hot, like driving through heavy traffic in a hot day.

https://youtu.be/8Ghsw54QwY4

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#4 ·
Did the external filter modifications a long time ago, the inline filter has less then 20000km.

We don't have ethanol in the fuel here (yet), and ran 2 full tanks in the same day from different pumps since this started.

No secondary plates in the throttle body, also removed a long time ago.

Did a TEKA fuel adjustment in June this year. The bike has never run better.

TRE fitted and have a gear/temp/voltmeter display made by a guy on the Croatian V-Strom forum. Voltage is fine.

Standard exhaust.

Even though I don't have the secondaries in, and since the fuel tank and panels are off the bike, will check if it needs to be adjusted because the STP sensor moves the STV actuator. (Just guessing here)

The thing that puzzles me is that idle (on a hot bike) returns to normal when the vacuum tube is disconnected from the air pressure sensor.



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#6 ·
Yes it has the canister. It's between the throttle body vacuum and air pressure sensor. I put a new hose and checked the canister. It's not clogged, no cracks on it. Hose is all the way on all connections.
Don't know it's purpose, could find any info about it.

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#7 ·
The STPS may have a dead or worn spot on it's wiper causing the STP actuator to hunt. There are two air pressure sensors in the FI system. The one you are removing vacuum from (IAP) and an ambient sensor(AP) located under the seat. My hunch is that removing vacuum from the IAP sensor is sending both sensors to ambient and fooling the ECU into shutting off power to the STP actuator. Just my two cents.
 
#8 ·
The STPS was generally where my mind was going as well. The secondary throttle position sensor is no better quality than the primary, so it wears out prematurely too.

Also, OP really needs to tell us what year DL1000 we're discussing here. There are some differences in the 1st gen DL1000 electronics that may or may not make a difference.
 
#9 · (Edited)
I have a KLV 1000, 2004 model.

Today I took the IAP sensor off a friend's 2004 DL1000 that works fine, and put it in mine. No difference, so it's not the IAP.

I checked the resistance on the secondary TPS. It was just a bit off then the values in the service manual. I adjusted it, no change.





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#10 ·
OK here is another theory to ponder. When the secondary actuator causes the primary throttle plate to open, The TPS is moving and the IAP sensor is detecting the change in vacuum. The ECS will receive these sensor inputs and increase injector flow. When you remove the vacuum line the IAP can no longer tell the ECU what is happening in the intake. Does the secondary actuator stop moving when you pull the vacuum line? One of the inputs to the STP system is gear position. Could there be a possibility that your add on gear position indicator is causing interference with the ECU signal?
 
#12 ·
Yes, the actuator stops moving when the vacuum tube is disconnected from the IAP, and the revs go up a bit and don't move.

The add on gear indictor was put on in 2017. I think it just reads the voltage from each gear and shows the gear accordingly.

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#11 ·
Man I was having some similar issues I had the ignition coils replaced with new OEM I did used the oscilloscope to see it was faulty. But if you can also determine by sound if the engine sounds louder when idle goes down it’s because one of the sparks is not firing properly. So it could be sparks and if not it would be the ignition coils. Goodluck!
 
#13 · (Edited)
The spark plugs are NGK Iridium and have about 15000km.
If it was an ignition coil shouldn't the problem be not only at idle when the engine gets hot, but also noticable at higher revs?

This is the rear spark plug, didn't take the front one out.

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#16 ·
Update on the problem I'm having.

A few days ago I installed the Smart Moto O2 eliminator and went for a 100km ride.
The jerking that I had around 3500rpm is almost completely gone.
I thought it was from the clutch basket, but it looks like it's not.
Unfortunately the inconsistent idle was still there. [emoji53]

So yesterday I disconnected the vacuum tube from the vacuum dumper chamber to the IAP, and capped the chamber.
Went for another 100km ride. The bike runs ok. I could smell that it was running a bit rich at start up, but not when it was warmed up.
Runs fine, the throttle is but more twitchy at lower rpm, but nothing serious. Runs much smoother at lower rpm's.
It was early in the morning, very little traffic, so the pace was mostly 100-130kmh with a brief 160 on an empty stretch.
The idle is exactly at 1200rpm and doesn't move a bit.

After exactly 99.3 km I filled up the bike with 5.76l (40.8mpg)

How come it runs better now? Can disconnecing the vacuum from the IAP have consequences in the long run?

P.S.
I did take a IAP from a friend's 2005 DL1000 before installing the O2 sensor eliminator, and disconnecting the vacuum tube, but the idle still fluctuated, so that means that my IAP sensor is ok.




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#17 ·
In the last few days I adjusted the fast idle, did a TBS again and checked the TPS again. The TPS jumps up around 1500rpm.
Reconnect the vacuum tube to the IAP.
All is good until the temperature gets close to 3 lines, and then the idle starts to go up and down. If I bleep the throttle it's good for about 10-15 seconds and then it starts again.

I have a TRE derestricor installed and if I put in gear the rpm's are ok?!

Today I removed the derestricor and this time if I put in gear the fluctuations are still there. When I reconnected it and put in gear the rpm's are ok.
The TRE deristicor makes the ECU think it's always in 5 gear (or 4th, can't remember, there is is different between USA and European models)

Really don't know what to do...



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#19 ·
Good to hear you found it.

One thought -- did you try plugging your ECU back in?

Sometimes it's just a bad or loose connection, and plugging and unplugging cleans or wiggles it enough to work again.

Good luck with the part search. There has to be a junkyard somewhere with a crashed Vee you can scavenge!
 
#20 ·
Good to hear you found it.



One thought -- did you try plugging your ECU back in?



Sometimes it's just a bad or loose connection, and plugging and unplugging cleans or wiggles it enough to work again.



Good luck with the part search. There has to be a junkyard somewhere with a crashed Vee you can scavenge!
Yup, plugged my ECU back in, and the problem is still there.

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#21 ·
Bought a 2008 ECU from the UK.

Connect it a few days ago and stated the bike in the garage.
When the temperature came close to 3 bars the idle stared going up and down again like with the old ECU.
Was pretty pissed at that moment...
So I disconnected the Smart Moto 0² sensor eliminator, and conned the O² sensor back.
No more inconsistent idle.

Note:
The inconsistent idle started before I connected the O² eliminator.

Finally went for a 100 km ride this morning and it feels like everything is ok. Even the stuttering at around 3500 is almost gone.
Was stuck behind a bus for a few km, rode in 3rd gear down to 2500rpm and it wasn't a rodeo ride.
Either this ECU was flashed using a Yosh or TEKA, or it's really a noticable improvement compared to the older ECU's.



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