I am aware the stepper can be totally disabled by using either an in line valve in the hose between the stepper and the airbox (or simply plugging it 100% of the time), but my bike seems so close to operating properly, I would like not to noodle with the stepper motor. It would make sense, I'm sure, to plug the hose and see if the engine does stay at 1100 RPM once warm. If that cures the issue, well, it'll be time to install either Todd's electrically controlled switch or a manually operated valve in line with the hose and quit fighting it.
Is there an adjustment one can access to change how the stepper motor actuates the throttle butterflies? Obviously, I'm NOT mucking with the 'sacred screw.' I've taken the advice of one of the tech advisors on this forum (tweaking the lengths of the throttle open/throttle close cables at the handlebar). The thinking was if the closing cable was slightly shortened (after slightly lengthening the opening cable), I'd be able to apply light force which would cause the idle to drop when at a stop. The throttle return springs are quite light on this bike. Currently, when the bike begans idling at 1500+rpm, I can lightly pull on the throttle linkage with my right hand, and the idle immediately drops to the desired speed. As soon as I release it, the idle speed goes back up to 1500-1600rpm. The cable adjustment idea made sense to me, unfortunately tweaking the cable length didn't appear to work. (Note - at the time the cable adjustment was suggested, the hanging throttle could be temporarily cured with a shot of WD40 on the throttle linkage springs)
I'll be doing a spring tuneup (plugs, TB balancing, TPS reset) which may help somewhat, but it appears to be more of a mechanical issue vs a tuning issue. Doing these things last year, plus canisterectomy, got rid of all the popping on overrun, but not the higher idle that takes place when the temps are on the cool side.
The drawings in the Teo Lamer parts manuals provide an illustration of the throttle bodies, but don't show (a) where the throttle cables attach, or (b) the linkage between the stepper motor and the TBs. And right now, it's just too cold in the garage to start removing the fuel tank to get a good look at the throttle linkage and cable attachment points.
Check the adjustment of you throttle cables. It sounds like there is absolutely no slack in the opening cable. There shouldn't be much slack in the opening throttle cable, but there should be some. Also be sure the closing cable has just about no slack to ensure closing the TBs mechanically. If the cables are correct and you still have the high idle, some have had success by placing a restriction in air supply line for the stepper. Then since it is a US bike, there is always the cannisterectomy.
John Zibell 2006 1100 Breva 1990 MK V LeMans MGNOC L-188
The stepper motor does not physically interact with the throttle bodies but works by injecting more or less filtered air upstream of the throttle plates depending on various inputs to the ECU
Click on the picture to enlarge
This is from the 8V training manual, but the 2V system is the same.
Attachments
Dan Raidt Central Florida MGNOC Rep 2Guzzis <at> Gmail.com 11 Griso SE "Tenni" 09 V7C "Pearl"
john zibell wrote:Check the adjustment of you throttle cables. It sounds like there is absolutely no slack in the opening cable. There shouldn't be much slack in the opening throttle cable, but there should be some. Also be sure the closing cable has just about no slack to ensure closing the TBs mechanically. If the cables are correct and you still have the high idle, some have had success by placing a restriction in air supply line for the stepper. Then since it is a US bike, there is always the cannisterectomy.
John, I will do this again. I may not have been aggressive enough on taking the slack out of the throttle return cable.
draidt wrote:The stepper motor does not physically interact with the throttle bodies but works by injecting more or less filtered air upstream of the throttle plates depending on various inputs to the ECU
Click on the picture to enlarge
This is from the 8V training manual, but the 2V system is the same.
john zibell wrote:Check the adjustment of you throttle cables. It sounds like there is absolutely no slack in the opening cable. There shouldn't be much slack in the opening throttle cable, but there should be some. Also be sure the closing cable has just about no slack to ensure closing the TBs mechanically. If the cables are correct and you still have the high idle, some have had success by placing a restriction in air supply line for the stepper. Then since it is a US bike, there is always the cannisterectomy.
John, I will do this again. I may not have been aggressive enough on taking the slack out of the throttle return cable.
Bob
John, I took another pass at loosening the open throttle cable, and it has plenty of slack when I apply finger pressure at the left throttle body (probably a bit too much now). I then adjusted the throttle return cable length as tightly as possible at the handlebar control (actually ran the adjuster off the threads and replaced it approx 5 turns. Still no good. Once warmed up, she's right back at 1500-1600rpm. But I can still either pull the right side throttle linkage, or push on the left side throttle linkage and cause the idle to drop to 1100.
Here's my thought. I'm now certain you're correct about the return cable needing adjusted, but it appears I'm going to have to make the adjustment where the return cable attaches to the throttle body. There's an adjuster nut visible there, but I cannot access it easily. Solution .... pull tank and airbox to get to the adjuster, and while in there, replace the inner spark plugs. That will make it worthwhile.
It sounds like you are going down the wrong road with this to me. The closing cable is not there to close the throttle under normal circumstance. With the closing cable disconnected the throttle should still close completely. The closing cable is like a back up cable in case the throttle does not close on its own in emergency situations. It is the springs that close the throttle under normal circumstances. However, if the closing cable does not have enough slack it can cause the throttle to not close or not close completely. If you disconnect the throttle does the idle still hang? If so I suspect you have a set up problem.
Guzzimoto may have a good point here. What put me on the closing cable road was the fact that you could get the correct idle by pressing or pulling on the throttle body plate linkage. Closely inspect this linkage. It should allow for the throttle body to hit the stop screw (don't touch that, it is the sacred screw). Inspect to see that nothing is interfering with the linkage. Also see if you can get some dry lubricant Into the pivots of the linkage. Also make sure the linkages are alined correctly and not binding.
John Zibell 2006 1100 Breva 1990 MK V LeMans MGNOC L-188
john zibell wrote:Guzzimoto may have a good point here. What put me on the closing cable road was the fact that you could get the correct idle by pressing or pulling on the throttle body plate linkage. Closely inspect this linkage. It should allow for the throttle body to hit the stop screw (don't touch that, it is the sacred screw). Inspect to see that nothing is interfering with the linkage. Also see if you can get some dry lubricant Into the pivots of the linkage. Also make sure the linkages are alined correctly and not binding.
Guzzimoto is quite possibly correct. However, before I do a pre-riding season valve adjustment, TB balance and TPS reset, I do want to follow through on getting the return cable adjusted, since my return springs feel slightly weak ... which I think is a distinct possibility based on how very light the pull is on the throttle. This costs me nothing but some time. If that doesn't cure the issue, surely doing the TB/TPS will, and if not, blocking off the stepper will take care of it. Since I'll be under the tank, I'm ordering a new air cleaner and two inner plugs today. (guess I should also purchase a small valve to install in line between air box and stepper motor.)
BTW - I don't intend to touch the 'sacred screw', but if one were to raise or lower idle with it, what are the effects? I'm imagining it would cause the idle to hunt, as the ECU attempted to set the idle to the rpm set in memory.
Thanks again, everyone, for staying with me on this. I'll drop a note to let you know how this works out.
Bob
Last edited by ohiorider on Thu Feb 16, 2012 6:52 am, edited 1 time in total.
