Idle rpm to high when warm

[poon]

I have a Breva 750 04 on which I have problem with the idel speed.
When it's cold I have no problems att all, the idle rpm are between 1000 - 1100.
But after riding for like 10 minutes and coming to a traffic light for a stop, then the rpm slowly goes up to 2000 and stays there. This repeats for every stop I do when I'm riding the bike.
I have done a synchronization with the help of my Twinmax. But it's not possible to do a perfect synchronization, in that case I get to high rpm at idle also at lower temp. So I have to adjust it a little bit to be unbalanced. The air bypass screws has to be closed also after balancing to get proper idle rpm. TPS is also reset after the synch.
I have done a test after I came home running the bike. I connected the computer and started Guzzidiag to read the engine temp was 98C and the idle 2000 rpm, I tried to disconnect the rod between the throttle houses, but there were no change of the rpm even after that.
So the next thing I did was to remove the oil temp sensor from the RH cylinder head and measuring it at specified temps. This are the results that I got,
At 20C 3,74 Ohm should 3,7 Ohm
At 100C 204 Ohm should be 220 Ohm
Could the result att 100C be the cause for the idle rpm at high temp?

Any suggestions are highly appreciated.

Br,
Peter

 

[john zibell]

The throttle sync should be done on a hot engine. Use a fan to keep it from overheating. I'm not a fan of electronic synchronizers, and prefer columns of liquid which to me is the most accurate. Do the high speed sync first and TPS reset. Then set the idle speed with the air bypass screws. Never touch the throttle stop screw in the LH TB. She may be a little cold blooded on start, but that is kind of normal and why you have a high idle lever on the handlebar.

 

[sign216]

John's right, if the cyl synch was done on a cold engine then that might account for odd behavior.
Note that to get truly warm it takes 20 min of running. And...be sure to have a fan running to cool the bike when you're doing the synch. I didn't once and it wasn't pretty.

Joe

 

[poon]

Hi John and Joe,
I have been following the instructions at this site,
wildguzzi.com/forum/index.php?topic=19680.0
I'm having the same twinmax as there, I also connect a computer running the Guzzidiag software to reset the TPS and also to keep an eye at the temp and rpm.
So the synch. is done at a warm engine, but when the synch is correct I get a too high idle rpm, it's running at 2000 with a warm engine. With cold engine it-s running ok at 1000 - 1100 rpm.
But as soon as it gets warm after 10 - 15 minutes and stopping at some traffic light the rpm slowly goes up to 2000.

I have measured the value for the air temp sensor today as well, it's 3.7 K Ohm at 20 degrees C as it should.
Gonna check the lambda sond also, it was a little bit too hot to stick my hands in there now

I have previously replaced both of the ball joints at the end of the rod between the TB, and also adjusted the axial gap to a minimum on the butterfly axel, it was about 0.6 millimeter gap there before.

/Peter

 

[sign216]

Peter,
I use a different software than Guzzidiag, but I thought GD would show you any error codes.
Are there any?
Joe

 

[poon]

Joe,
Guzzidiag has a page to read error codes from the ECU, but there are no errors there after reading the ECU.

Br,
Peter

 

[john zibell]

Close the air bypass screws equally a little bit at a time to lower the idle RPM to an acceptable level when the engine is hot. Idle sync is not as important as hi speed sync. Your cold idle will then be a little low, but that is why you have the high idle lever. Didn't I say this already?

 

[poon]

John,
the air bypass screws are both totally closed.
I wrote that in my first post

/Peter

 

[john zibell]

John,
the air bypass screws are both totally closed.
I wrote that in my first post

/Peter

Didn't click that you had them fully closed. Has the paint at the throttle stop screw been broken? Someone in the past may have done what shouldn't have been done and moved the throttle stop screw. To achieve a good idle speed on good TBs the air bypass screws need to be open 1/2 to one turn or more.

 

[poon]

John,
the air bypass screws are both totally closed.
I wrote that in my first post

/Peter

Didn't click that you had them fully closed. Has the paint at the throttle stop screw been broken? Someone in the past may have done what shouldn't have been done and moved the throttle stop screw. To achieve a good idle speed on good TBs the air bypass screws need to be open 1/2 to one turn or more.

From what I can see there is some yellow paint there, but not all over the head, it's not so easy to see there.
Will try to find a mirror and try to watch it a bit closer.
But I have had this bike since 2009 and it's been running nice up to now.
The air bypass screws has been open 1/4 turn before to get a good idle.

 

[john zibell]

Now we know this is a recent occurrence, hook up your diagnostic software when the engine is hot to read the sensors in real time. It may give us some indication of what is going on. Pay particular attention to the engine temp sensor, air temp sensor and TPS reading at idle. I know on VDSTS/Centurion you look at Alfalin_0 for the TPS reading, on your software I don't know the correct channel.

 

[poon]

Now we know this is a recent occurrence, hook up your diagnostic software when the engine is hot to read the sensors in real time. It may give us some indication of what is going on. Pay particular attention to the engine temp sensor, air temp sensor and TPS reading at idle. I know on VDSTS/Centurion you look at Alfalin_0 for the TPS reading, on your software I don't know the correct channel.

I have just checked the paint on the throttle stop screw with help from my mobile camera, not so easy to get the focus correct, but it seems like it's ok.

Then I played around a bit with Guzzidiag for a while and then I suddenly lost contact with the ECU and it refuses to get connected again. So I checked all the cables in my cables from computer to the diagnostics connection and they seems to be OK. Then I removed the ECU to check the cables from that one to the diagnostic connector, but only 2 of the cables goes to the ECU and one of them disappears with a bunch of other cables, so I could only check those going to the ECU and they were OK, will try to find out where the other cable goes later, to dark outside now

The different selections I can do in the Guzzidiag is bit different, it looks like this,

 

[john zibell]

Try another picture of the paint. To me it looks broken, but it just may be the focus. If you can get a screen shot of the display with the bike hot (High idle condition) it might tip us off to something.

 

[sign216]

Also, check for an leak in the intake manifold, or the exhaust header. A leak there could cause a high idle, which is masked on a cold engine.

Joe

 

[Penis Rotor]

You said you had replaced both the ball joints on the linkage arm? How did you assess the distance between the ball joints when reconnecting the rod with the new ones on?

Pete

 

[poon]

You said you had replaced both the ball joints on the linkage arm? How did you assess the distance between the ball joints when reconnecting the rod with the new ones on?

Pete

I measured the rod so it connected to the ball joints without opening the valves.
Then I do the synchronization on the LT screw.

 

[poon]

Also, check for an leak in the intake manifold, or the exhaust header. A leak there could cause a high idle, which is masked on a cold engine.

Joe

I can't see or hear any leak in the exhaust, but for the intake manifold it's a bit harder to fins any leak.
A tip I've seen is to get some start gas can and spray it outside of the throttle/intake, if the rpm rises it's an indication of a leak somewhere there. Has anyone else seen that tip before? sounds like it's worth to try that.

 

[john zibell]

Also, check for an leak in the intake manifold, or the exhaust header. A leak there could cause a high idle, which is masked on a cold engine.

Joe

I can't see or hear any leak in the exhaust, but for the intake manifold it's a bit harder to fins any leak.
A tip I've seen is to get some start gas can and spray it outside of the throttle/intake, if the rpm rises it's an indication of a leak somewhere there. Has anyone else seen that tip before? sounds like it's worth to try that.

It is safer to use WD 40 or carb cleaner instead of ether. I've done that to detect intake/vacuum leaks.

 

[sign216]

Also, check for an leak in the intake manifold, or the exhaust header. A leak there could cause a high idle, which is masked on a cold engine.

Joe

I can't see or hear any leak in the exhaust, but for the intake manifold it's a bit harder to fins any leak.
A tip I've seen is to get some start gas can and spray it outside of the throttle/intake, if the rpm rises it's an indication of a leak somewhere there. Has anyone else seen that tip before? sounds like it's worth to try that.

It is safer to use WD 40 or carb cleaner instead of ether. I've done that to detect intake/vacuum leaks.

I used both WD40 and carb cleaner to find an intake leak I had on a V7. The leak was on the metal intake runner, where it meets the head. The sealing gasket there wasn't thick enough, and I had to end up using two gaskets to take up the room. I could tell this was a problem area. The metal of the intake contacts the head, and where the two meet, one gasket may not be enough to take up all the room.

And check the exhaust header too.

 

[poon]

Try another picture of the paint. To me it looks broken, but it just may be the focus. If you can get a screen shot of the display with the bike hot (High idle condition) it might tip us off to something.

I have just updated with a new picture, the seal seems to be broken, but that might happen from normal wear and tear I guess. I don't know how much torque that's needed to screw change it, if it's possible to change by itself if the seal has been broken. Haven't been able to do any further checks yet, it's been raining for two days on and off here and I have to be outside to do work on the bike