Lumpy Idle

[Constant Mesh]

"Something I didn't mention - at cold startup it idles normally (at ~1500 RPM IIRC) without the lope."

This may point you toward the answer.

The wax motor cold idle system may be introducing small air flow unbalances between the cylinders.

If one of the sliding valves on the throttle bodies is not closing all the way when normal coolant temperature is attained you would have a bit different air flow through that throttle body.

One might expect a good TBS to compensate for such an unbalance if it's persistent and unchanging.

If the unit has been sitting unused a long time the fuel may have left a sticky residue in those sliding valves. Maybe one of them is misbehaving and not closing completely as it should.

I would expect the problem to be associated with possible differences between cylinders. The oxygen sensor, TPS and many other sensors affect all cylinders equally.

You probably need to focus on where differences can occur.

 

[Fred W]

The other important thing that happens at cold start is that the temp sensors tell the ECU the engine is cold and enriched the fuel mixture. To me, this is a far more likely reason for the lumpiness to go away. The question remains, why is the fuel mixture too lean at normal operating temps? The vacuum leak idea has merit.

 

[RossKean]

The other important thing that happens at cold start is that the temp sensors tell the ECU the engine is cold and enriched the fuel mixture. To me, this is a far more likely reason for the lumpiness to go away. The question remains, why is the fuel mixture too lean at normal operating temps? The vacuum leak idea has merit.

Lean surging or imbalance between cylinders. This has been noticed after a (presumably correct )TBS so while there is some merit to Constant Mesh's wax motor suggestion, I will hold off on that until a TBS makes a big change in the behavior. If it does, then some dismantling and cleanup might be in order. The whole wax motor thing seems to be a "Mickey Mouse" way of doing the cold idle enrichment but it seems to work extremely well. I have never found anybody who had a serious issue with it - except one post by Radio Howie a number of years ago.

We are still down to a vacuum leak (TBS caps or hoses) or an O2 sensor issue as primary candidates to cause this leanness. These were among my initial hypotheses and I'm happy to find some agreement. Work on it might not happen this weekend but before very long!! This response is just so damn regular and consistent - the answer has to be something simple!

 

[Fred W]

Wax motor doesnt enrich the fuel mixture. That is done by the ECU based on temp sensors. The wax motor only adds additional (bypass) intake air to raise the idle speed when cold. And on second Gens it doesnt raise the idle speed all that much, presumably to make it compatable with the auto clutch (ES) models.

As a theory, if the TBS was badly out of adjustment, adding bypass air during cold start could mask the symptoms. Also remember that on 2nd Gens the idle adjuster is another little bypass air manifold that can introduce misbalance between cylinders at idle. Hooking up a sync gauge will be interesting.

 

[RossKean]

From what I have seen on the 2011 vs the 2007, the cold start increased engine speed is greater - close to 1500 RPM vs a base of 1000. Makes sense when you consider that the AE was no longer sold in North America. (But that difference may be related to whatever is going on here.) I guess I was mixed up on the function of the wax motor function - makes sense.

I agree that it will be interesting to see if the cylinders are balanced. I will also be interested to see where the starting point was on the TBS - I'll probably start them all at 3/4 turns out. Yes, I know about the idle screw on a Gen II. I also know that you lose the range of idle adjustment if the TBS is messed up or if you have the wrong starting point - i.e. reference screw backed out too far. Doesn't Gen I essentially adjust the throttle stop position instead?

But I will check the O2 sensor and look for vacuum leaks first.

I'm not terribly concerned with it - I suspect it is something simple. Others have said that they also have a "lumpy" idle but I wonder how they compare to what I am getting?

 

[ERS]

Hey Ross,

Just listened to your video, That is nothing like the loopy idle I have. Mine doesn't affect rpm and isn't that regular, it just changes tone for an instant every few seconds. Have you run ringfree or seafoam through it yet? Vacuum would be a good start.

 

[RossKean]

It has had a dose of Ringfree and 6,000 km of running. Doubt that it is gummed up at this point but may do a Seafoam treatment - just because I can!

 

[ERS]

Agree - 6000km steady running should be as good or better than a Seafoam treatment!

 

[mech 1 twa]

I have a throttle body and injectors from a 2007 if they fit? TPS is broken though. 22k came from an engine swap into Gen 1 . $100 plus shipping . Try a few things so solve first.

 

[RossKean]

I have a 2007 sharing garage space with the '11 so if I get into parts swapping for diagnostic purposes, I'm good to go, thank you! (almost 190,000 miles on that one!)

The thing just runs too well for it to be anything very serious. Power is very good, no hesitation, decent fuel mileage - for there to be a major mechanical issue, it just wouldn't run that well. I hope to be able to get into it at least a bit tomorrow. Check out O2 sensor and vacuum leaks. Have to build a manometer for the TBS - I've always scheduled them at a "tech day" somewhere (and probably don't do it as often as I should).

I have a little butane torch that should be good for checking for vacuum leaks (unlit, of course). I think it should work as well as the WD-40 some people use and without leaving a mess behind. Starting fluid would be OK as well but I don't have any.

Somebody suggested to me that it could be a function of a more freely-flowing exhaust making it run leaner (Staintunes) but I think that notion is a carryover from the days of carbed V-twins where you had to rejet if you made a significant change in intake or exhaust. With O2 sensors, sophisticated ECUs and fuel injection, the system can compensate for a lot.

Previous owner removed the PAIR (as many of us have done). Not sure if he used the Wynpro plates or nipples over the ports where the hoses hook up to the valve cover. Good spot for a major leak that would mess up everything! Especially if typical vacuum caps were used - will have to check!!

Edit: I checked the information with the bike and apparently the Wynpro plates are on it - just have to make sure they are tightened down fully.

 

[RossKean]

One other small bit of information I just discovered. I was doing some reading on the forum and apparently the previous owner did the "Barbarian Jumper Mod" on this bike. In one post, he mentioned that the CO values were changed from 0 to 3. I don't know what that actually means and whether there is any possibility that it could mess up the idle. (is this much change a lot or minimal?) Since the BJM has been done, I guess I can go in and look to make sure that settings weren't inadvertently changed to some odd value at some point. The thing about the BJM and subsequent changes in the CO numbers is that it involves settings that can affect each cylinder differently. (BJM just adds a menu item that enables you to read and change CO values - it shouldn't do anything unless settings are actually changed)

Does anybody with a later Gen II who has done the BJM remember what the stock settings were? This was a far more common "fix" on Gen I and earlier Gen II. I also seem to remember that there were different settings for each cylinder on earlier bikes but later Gen II were typically all the same??? Am I remembering correctly?

Since the BJM requires removal of the ECU plug and popping pins out, it would probably make good sense to pull the connector and make sure everything looks OK there. A funky connection at the ECU might do bad things to the response at idle.

Edit: I read somewhere that for the earlier GenII, 5, 18, 18 and 21 were typical settings for '06 and '07 ????

And maybe 10, 10, 10, 10 on 2008. I saw a reference to 0,0,0,0 on a 2010.

Given the changes that some people have done with the BJM, going +3 (from 0) doesn't seem huge.

 

[mech 1 twa]

BJM + 3 is not a huge change. I bumped mine up 7+ Gen 1 I don't remember what the original settings where. Lift the tank issue could be in plain sight.

Doubt its a connector issue at ECU runs to good. No check engine light . Mufflers not the problem at idle.

 

[RossKean]

BJM + 3 is not a huge change. I bumped mine up 7+ Gen 1 I don't remember what the original settings where. Lift the tank issue could be in plain sight.
Doubt its a connector issue at ECU runs to good. No check engine light . Mufflers not the problem at idle.

Agree - I will check the BJM just in case something strange happened with the settings but +3 shouldn't be significant. Crappy weather and other stuff kept me away from it today - might get an hour or two on it tonight. In addition to TBS caps, vacuum hoses and O2 sensor connection, I will verify battery connections - sometimes responsible for weird shit! Mufflers (and air filter) very unlikely to make much difference at low RPM. In your experience, is something like butane or propane suitable for scoping out vacuum leaks?

I just exchanged emails with the previous owner. He had told me that he always experienced some idle variability but after he listened to the video I posted, he said not close to that much. It is clear that something has changed. He also confirmed that a number of years ago he had an issue with a partially blocked fuel injector. If there was a reoccurrence due to the bike sitting for over a year with stabilized fuel in the tank, I think I would expect other symptoms. Would swap the entire fuel rail from my '07 before trying anything else in this area other than fuel additives.

 

[mech 1 twa]

I have never tried butane or propane for a vacuum leak. I use Castle Shop Solve . Comes in spray can with with small red tube. Like carb. cleaner but its all alcohol based. Pin point leaks with a short spray. Very flammable....... Doesn't eat plastic or rubber parts. Won't find it at any auto parts places... Friend of mine gets it somewhere

Doubt injector issue. I know people who never use any additives and don't fill tank sits all winter always starts. lucky I guess.

 

[RossKean]

OK then. Does this sound a bit better?? Maybe not perfect - will see if a TBS helps.




Battery connections solid.

O2 sensor properly connected.

Plug caps firmly seated.

Bunch of other connectors checked.

13 V at battery at idle. Up to 13.7 ish at 3000 RPM

Noticed some voltage variability with the loping idle but its REALLY hard to tell with the refresh rate of a DVM.

(I'll get some other opinions on that at another time)

Lighting in the garage not so good for close work and my eyesight and the batteries in my headlamp died...

Did notice something.

Put some new caps on (all four) and the result is the above video. (Also stepped up the idle a wee bit)

I think it is OK but I'll reserve final judgement until I put a few miles on it.

I appreciate the suggestions.

 

[TownsendsFJR1300]

Sounds normal now.

I gather you manipulated the cap to see if it was broke all the way thru?

 

[RossKean]

Sounds normal now.
I gather you manipulated the cap to see if it was broke all the way thru?

It was all the way through, and others had deteriorated as well. Not sure if they were all leaking but there was an immediate change when I started it after replacing the caps..

 

[Fred W]

Yeah, now thats the normal lumpy idle Im used to. Sounds completely normal now.

That perforation in the vacuum cap looks like maybe someone had used pliers or hemostats to pull the caps off previously and nicked them.

The first thing Ive done with both of my bikes is to pull those little wire retainers off the caps and ditch them. The caps are covering vacuum ports. The vacuum is sucking the caps on tighter. No need for retainers. And when I eventually replaced my caps I bought some extra tall ones that make removing and installing with my fat fingers much easier on a hot engine.

 

[Brodie]

Looks like it's time for me to replace the caps on my 10 year old '08. The idle is just fine, however, as the saying goes: An ounce of prevention...

Thanks!

Brodie

 

[Brodie]

Not to thread jack this, but that looks like a Penske rear shock installed on your '11. Have you checked at it's yoke for any shearing underneath?

Brodie