Floating idle last issue post big bore, any ideas?

[Subarubrat]

After riding off the break in miles I started running it harder and working on the tuning to see what I could get done on my own. So far AFRs are good across the board, there is no knock, and performance/ responsiveness is excellent. The one issue that I am not ready to hang on the tuning just yet, but I don't see any mechanical reason behind, is the intermittent hanging idle. A little over half the time the idle will hang around 2k RPM, it will drop to normal 1,100 RPM if I blip the clutch in a high gear. Before I start chasing ghosts in the maps I thought I should ask around about known Buell hanging idle issues. Any known causes that have plagued you?

Throttle and return cables are new btw.

Build is:

1275cc cylinders/ pistons
Cometic gasket kit
Crush head porting (7mm valves, 1.900 intake, 1.610 exhaust, conical springs, titanium retainers, 30deg squish band)
605/591 cams (some clearancing was needed for the bearing race but a nice fit)
3/8 hammer pushrods
Throttle body port/match
And I threw in some other bits like new wires, plugs, new oil pump gear, header wrap, and I already have the K&N and Drummer

Using Buell race tune, 116% AFV, Enable Open Loop off, and a notch of base timing retard added in. My next project is working on the ignition maps to get a bit more sophisticated than a wholesale timing reduction.

 

[user_deleted]

qualifier: i have no experience or knowledge with "custom tunes"....ecm jibberish....or hot-rodding an XB motor. having said that a typical XB "hanging idle" issue....assuming the cables are lubed and adjusted properly and sufficient slack is dialed into the puller cable is the result of 1 or more of the following:
1-tps in need of reset along with curb idle adjustment to 1000 rpm on pre 2008 models
2-warm motor curb idle speed set too high
3-faulty neutral sensor safety switch.

 

[Chicknstripn]

Test for an intake leak.
Last time I had a hanging idle my intake seals were leaking.

 

[lowkey]

Were the pistons/cylinders from Hammer? I would guess they have "been there done that" with whatever issues tuning wise go along with bigger pistons/ported head/cams. The 1000-1050 idle for a stock 12 may be screwing you up some but it's just a guess. Aside from the classic catch at 2k RPM that points to TPS/idle value to high VS fuel/timing maps or intake leak, are the RPM's slow to fall? As in 5k blip to idle, same as a stock bike? What is your TPS value for your 1,100 idle RPM set at? If it was me I'd back it down to 950 idle and see if that takes care of it, if not leave idle there and pull 2% at a time from 2K to 1K in fuel maps, could be your cams/heads are flowing to well for the maps in that area.

Also you have widebands or no?

 

[BuellyBagger]

qualifier: i have no experience or knowledge with "custom tunes"....ecm jibberish....or hot-rodding an XB motor. having said that a typical XB "hanging idle" issue....assuming the cables are lubed and adjusted properly and sufficient slack is dialed into the puller cable is the result of 1 or more of the following:
1-tps in need of reset along with curb idle adjustment to 1000 rpm on pre 2008 models
2-warm motor curb idle speed set too high
3-faulty neutral sensor safety switch.

Plus 1 on #1 and 2. Had the same issue beginning of last season after cleaning the TB and not reseting the TPS. Try setting curb idle a bit on the low side, im sure your motor "lopes" even a bit more than normal so it may be hard to hit that exact 1k mark

edit: a bit like 50 rpmish NOT 100 or 200 rpm low

 

[Subarubrat]

The metal bits were all from Hammer, who provides great service but is up front that they serve the Sportster market and the parts happen to also fit the Buells. I get it, the Sportster market is huge and Buell is small.

I tried several steps today, but the fix was a few things that were probably my tolerances ganging up. I picked up a new TPS, part TPS213 at my local Advance Auto for $38 and installed it with the fasteners loose and rotated it till I felt the spring pre-load then tightened them. TPS reset, then set for 6deg and fired it up and it was real close to 1100RPM. The floating idle was almost gone, I pulled 2% out of my enrichment and set fuel cut on decel to ON in the ECU params and all was well!

The performance is pretty much spot on now, and AFRs are OK across the board, cruise is about 10% greedier than it could be on fuel and I am looking at the maps and starting to dissect them to do surgical changes Vs broad brush changes, but for now I have a safe tune with great responsiveness.

 

[user_deleted]

and set fuel cut on decel to ON in the ECU params and all was well!

my understanding has always been that this results in some incredibly annoying slow throttle response off idle.
check with ecm gurus. i told those punk-ass kids to get off my lawn the other day but know they're still hanging around here.

 

[njloco]

Did we listen ? I know I didn't, usually had to get a boot up my butt before I did listen.

 

[rchuff]

Say what ! Is this thing on!!! I can't hear you!!! Here we go again!!!! No body is listening!!!!!!!

 

[lowkey]

I tried several steps today, but the fix was a few things that were probably my tolerances ganging up. I picked up a new TPS, part TPS213 at my local Advance Auto for $38 and installed it with the fasteners loose and rotated it till I felt the spring pre-load then tightened them. TPS reset, then set for 6deg and fired it up and it was real close to 1100RPM. The floating idle was almost gone, I pulled 2% out of my enrichment and set fuel cut on decel to ON in the ECU params and all was well!

The performance is pretty much spot on now, and AFRs are OK across the board, cruise is about 10% greedier than it could be on fuel and I am looking at the maps and starting to dissect them to do surgical changes Vs broad brush changes, but for now I have a safe tune with great responsiveness.

Nice find on the TPS sensor for a very good price, I can't seem to find it for that cheap though https://shop.advanceautoparts.com/p/wells-vehicle-electronics-throttle-position-sensor-tps213/10305490-P is this it at $66.99?

As for "fuel cut on decel" function, it is said to pull somewhere between 5%-10% across the bottom two rows right of idle RPM, since it works in the background this was a best guess from either Mike Cobb or Gemini, both of which have massive amounts of tuning knowledge of these bikes. The engine braking forces can go up drastically with this much fuel removed, I myself thought I would like it more aggressive but turned it back off after about 3 days... the better option is to just pull fuel in small increments (1%-2%) out of these rows, think of it as working on a slide scale from the stock decel to the more/almost to aggressive decel you get when checking that box.
Also before you start going crazy with tuning the maps I suggest you search "square idle" and work on that then move to data logging for map adjustment. Some other things to consider are I think you said your AFV is in the 116% range right? You need to see what the highest cell value is in your fuel maps right now (pre-tuning) and keep in mind the highest value you can ask for is 255! Your ECM may already be asking for more than 100% possible fuel.

Here is an hypothetical example: Highest cell value is 245 but AFV is 116% right?
245 value is at the assumption your AFV is 100%, 116 divided by 100 is 1.16, 245 times 1.16 is 284.2! But at a 245 value 100% AFV you only have 1.04% more fuel to offer up!

If you find this to be the case you can change the FPR out and globally back the maps values down to compensate, giving you more headroom at the highest values.

 

[Subarubrat]

I walked into the store and gave them Duralast part# TPS213 and they didn't have that (or the Wells part you linked to) in stock but the cross reference had two, one for $38 and one for $40 something and they both looked identical, it installed and calibrated fine.

I have a stand alone wideband and a J&S knock monitor that I have been using along with live data on ECM Droid so I have pretty good data, I would love to know the injector duty cycle and how much headroom there is but I don't have any lean spots so I'm obviously not hitting max. AFV ended up at 114% and having the fuel cut on decel turned on seemed to clean up the extra fueling at the low end just above idle which plays very well with your 5-10% estimate. With my AFR looking good across the range I am going to focus on the ignition maps, but I will probably return to the fueling to see if I can get a leaner burn in cruise for a few more MPGs. I called Hammer again and spoke with Dan regarding setting the redline, with the new valvetrain I thought there might be some room for upping that but he suggested leaving it at the stock values.

I put a few hundred miles more on it this week and the performance is much better than stock, not as much as my EBR1190RX, but it pulls harder than stock especially in the higher revs, and responsiveness is better by far.

and set fuel cut on decel to ON in the ECU params and all was well!

my understanding has always been that this results in some incredibly annoying slow throttle response off idle.
check with ecm gurus. i told those punk-ass kids to get off my lawn the other day but know they're still hanging around here.

No problems with that, probably due to the above reason.