| Author | Message | ||
     Mark_weiss |
The last few mornings have been in the 30s and my Uly has been difficult to start and initially runs poorly. Today I realized that once started, the engine is not running at an elevated idle (I know, how did I miss that?) but at normal idle right away. This sounds like the IAC is not functioning. Is there an easy way to test the IAC or do I have to remove the airbox and take a look? No CEL so far and once warmed up the bike runs fine. | ||
| Griffmeister |
Unless someone else has an idea it looks like you already know your options. Thinking logically, if there’s no code then the ECM thinks everything is working fine electrically. This would indicate a mechanical fault such as the sticking you suggest. If this is the case, I would think you’d also see a difference between clutch in and out even when warm. Normally when you come to a stop and hold the clutch in, the idle will be higher than if you put it in neutral and let the clutch out. If there’s no change then it may very well be sticking. Hopefully somebody knows a test where you don’t have to take anything apart. | ||
| Ourdee |
If you come to a stop with the clutch lever in and the bike in first gear, as you let the lever out the engine RPMs should go up with out twisting the throttle. | ||
| Hughlysses |
If it’s the IAC, you may be able to remove it and clean it by spraying carburetor cleaner through it. IIRC, the mist from the rocker cover breather hoses is known to foul them up. If you want to replace it, I think someone’s identified an auto unit that will work, so that would be worth investigating. | ||
| Swanthog |
Hi, Mark. I had this same issue and am presently working around it by disabling closed loop mode (https://www.buelltooth.com/open-loop.html). There is no IAC valve on my 2006 Uly only a TPS sensor and idle control cable (maybe added later years?) Here are some useful snapshots from the manual freely available here (https://www.manualslib.com/download/804797/Buell-Ulysses-2006.html):    | ||
| Falloutnl |
I had a 2009 Scg that wouldn't idle properly. I replaced the IAC at the cost of almost 200 euro. Didn't fix the issue. That annoyance, plus the fact I never loved the way it handled, added up to me selling the bike. Sorry, not a helpful comment other than maybe the suggestion that you try everything else before replacing that expensive IAC part. | ||
| Mark_weiss |
My bike has no idle quality issues. The problem occurs only during cold start conditions. I have only just noticed that the startup idle is not at 1500 rpm or so, but at 1000 (indicated). In the past, startup idle would be around 1500 and within a minute or two would drop to about 1200. Sometime after that, idle would settle at a bit over 1k. This morning the bike started slow, jumped to about 1400 within a very few seconds, then tapered to about 1k. I think that after 78k miles, the IAC is hanging up when it is cold. I will look into cleaning the valve. | ||
| Falloutnl |
Yeah, if anything, it's really easy to get to and try to clean. Who knows, it might fix your issue. | ||
| Swanthog |
I'm at a loss. Can someone show me where the IAC is on this bike? (have a page from the manual?) Thanks! | ||
| Falloutnl |
Like you said, your '06 Uly doesn't have it. On post '08 bikes it's located next to the throttle body. (It kinda looks like a tiny inverted oil pump, in black). (Message edited by falloutnl on December 21, 2018) | ||
| Swanthog |
Thanks, Falloutnl. My experience with IAC valves on on cars is the car will die when coming to a stop. This has been the failure mode every time. | ||
| Froggy |
Same thing happens on the Uly should it really fail. If it is just acting up it won't idle right, but the the throttle plate is too closed to keep the bike running with the IAC completely cutting off air. I've seen it taken apart, cleaned and rebuilt with success | ||
| Sharkguy |
Here is the IAC clean out procedure I documented back in 2011. Maybe it will help. http://www.badweatherbikers.com/buell/messages/142 838/634269.html | ||
| Mark_weiss |
I had the IAC out this morning. Before removal I swtiched the bike on and I could hear and feel that the stepper motor was running. With the valve out, everything looked quite clean. I still wiped things down before reinstalling the valve and checking its operation. The IAC works by fully extending the plunger and then presumably retracting it a programmed amount. Everything seemed to work today, but it was over 50f while I was doing this. I'll see what happens tomorrow when it's about 38F. | ||
| Mark_weiss |
Seems to be working again. | ||
| Falloutnl |
Well, that's good news. Great work! | ||
| Mark_weiss |
I decided to check the IAC performance when the clutch switch button was pressed in. Nothing happened. I checked that the clutch switch enabled starting-in-gear, so it seems that the switch is OK. More to investigate. | ||
| Griffmeister |
Did you put it in gear, too? I’m not sure now but maybe the difference is between clutch in/in gear and clutch out/in neutral. Don’t quote me on that. | ||
| Ourdee |
I think dif. is running in gear with clutch in -vs.- running in gear with clutch partial release. That is if you want it the IAC to move. | ||
| Mark_weiss |
Yes, the bike was in gear to check the IAC response to the clutch switch. When in Neural the idle speed should not change if the clutch lever is let out. In gear, the idle speed should increase when the switch's button is pressed in. |
