GRiSO running odd after throttle body sync

So last week I finally got around to setting my valve clearances and after I did this I also did the throttle body sync. I followed the guide to the letter, reset the TP after every step etc.. For the idle, the left air intake screw is now closed (was open before). The right one is now slightly open (was closed). This gave near perfectly matched bars on my manometer. I did notice when doing the idle that the manometer bars didn't get very high (about a quarter up) not sure if thats okey or if the bars should reach higher.

Anyhow despite how everything went well, since then I've had the following curiosities. First of all when actually riding its a noticeable improvement over how it was. No odd heavy vibrations anymore and a smoother ride overall.
However my idle RPM is very high. I've had problems with this since having it serviced at the dealer, but now there is a marked change to how it was before my 'tuneup'. Before it would be somewhat erratic, hovering between 1250 and 1400. Now its around 1450-1500, so noticeable higher
In addition, when idling in front of a red light etc. (so in gear with the clutch disengaged) rarely the engine cuts off for a millisecond (like a heart skipping a beat) as if its out of fuel or starved for air, then recovers and continues running.

Any pointers what the problem can be? Should I open up the air intake screws more and experiment with it, getting a balanced manometer result with more air getting in?

It's either tuned correctly and balanced correctly or not, and part of the requirement is to have at least one air bleed screw closed....Mine idles at around 1450 on dash (shows less on guzzidiag) and I don't think that's a problem personally. I'm not sure but could be that idle speed is just a function of where you end up relative to stepper action range, because it's stepper job to manage idle using more/less air above and beyond air bleed quantity.

For 'hard stumble but not stop' I had same pre-rollerisation & put it down to either tappet/cam deterioration or lambda issue - it sometimes felt like a clunk inside. It went away post rollers and new map with lambdas off. It did seem to stop doing it when the lambda warning came on (finebau at the time - don't ask !) but I couldn't be sure as it was random and intermittent issue.

PS: Please stick your provenance statement at the bottom of your signature & will help tune the responses Year-Model-rollers- etc

paulbrice wrote:

For 'hard stumble but not stop' I had same pre-rollerisation & put it down to either tappet/cam deterioration or lambda issue - it sometimes felt like a clunk inside. It went away post rollers and new map with lambdas off. It did seem to stop doing it when the lambda warning came on (finebau at the time - don't ask !) but I couldn't be sure as it was random and intermittent issue.

Alright, I'm not too worried then. Thanks! Anything I can try with guzzidiag? If its temperature/lambda related (it is a fair bit colder since a week or two) could tweaking the CO trim do something positive?

paulbrice wrote:

PS: Please stick your provenance statement at the bottom of your signature & will help tune the responses Year-Model-rollers- etc

Done. Excellent suggestion.

Hmmm....tweaking CO trim means you are running map with lambdas off anyway ??

I still think it was caused by the tappet-cam issue but can't say how (I could start rabbiting on about micro-welding but no data to support it :-))

No I run a stock map. I didn't realize the lambda sensor overrules any CO trim changes that I make, shows how much I know
If its indeed caused by the flat tappets at least I know that will get fixed eventually.

ps. would it be safe for the engine to just turn off the lambda sensor, tweak the CO trim, and ride it like that? Or does turning off the lambda require a specially tweaked map? Just wondering. I'm assuming it will use more fuel in any case without the lambda?

Turning lambda off requires remapping.

1. Is it really idling at 1450? Is that via Tacho or GuzziDiag?
2. The stumble at idle - is there just a dip in the idle speed, or is there a 'chuff' sound when it does it?

It may be due to the flatties.

Try squeezing the hose that runs from the stepper motor to the throttle bodies to cut off the influence of the steeper motor. If this improves the idle speed then fit a pneumatic switch or disable permanently. Cold motor idle will be erratic without the help of the switch.

1. Via tacho, but I can also hear that the idle is faster. I'll doublecheck the idle speed in guzzidiag.
2. It's not just a dip in idle speed, its as if the engine cuts out for half a second then re-engages. Sound is hard to describe but 'chuff' will do, though its more of a 'splutter'

kiwi dave wrote:

Try squeezing the hose that runs from the stepper motor to the throttle bodies to cut off the influence of the steeper motor.  If this improves the idle speed then fit a pneumatic switch or disable permanently.  Cold motor idle will be erratic without the help of the switch.

Thanks, will give that a try.

Look closely at the throttle bodies. When it 'Chuffs' see if you can detect the throttle butterfly spindles twitch. If they are it's because it's spitting back through the TB's. The most likely cause for this is someone having monstered the throttle stop screw or linkage rod. All too common I'm afraid. Just had to replace the TB's on my mate Peter's 2012 Stelvio.

Pete

Thanks Pete, though I think I can rule that out as the yellow paint is still intact. The sputter happens quite rarely and irregularly, so watching the throttle bodies until it happens may be futile but I shall have a look anyway.

This may be a strange thought but could water in the tank be the cause for it? It's been raining a lot here for the past couple of days, and when I stopped at a fuel station today I noticed a fair amount of water underneath the tank cap having accumulated in the rim to the left of the tank entrance. Thought I assume water would also cause hiccups when riding and not just at idle.

There is supposed to be a drain from that area, it's one of the nipples at the back of the tank. Make sure it isn't blocked.

Pete

My idle got a lot better (even before bettles map), after spraying some carburator cleaner in the pipe that the stepper draws air from the airbox - while the engine was running.

It coffed, stambled, stalled at each burst of cleaner, used the throttle to keep it running, some smoke came out from the exhaust. I believe some dirt had accumulated in the valve (the stepper mottor moves a valve), not allowing it to move corectly.

paulbrice wrote:

For 'hard stumble but not stop' I had same pre-rollerisation & put it down to either tappet/cam deterioration or lambda issue - it sometimes felt like a clunk inside. It went away post rollers and new map with lambdas off. It did seem to stop doing it when the lambda warning came on (finebau at the time - don't ask !) but I couldn't be sure as it was random and intermittent issue.

This was exactly my experience. I had a very high idle, that bad stumble, and even the engine warning light coming on at times. After the rollerization, beetle map, and TPS reset, it was all cured: now I have a rock-steady 1100 RPM idle and no stumbles. (And of course the engine pulls like mad at all revs due to the brilliant map)

Thanks all, I'll have a go with all your suggestions when I have time next week, and report back. The fueltank water drain turns out to be completely clogged at least. I opened the tankcap wednesday and there was half a cup of water flushed into the fuel The drain was blocked on multiple points and especially about 10 centimeters in. I cleared some poking it with a metal wire but eventually about 8-10 centimeters in it just won't go any further even with force. Will remove the battery next week and see if I can better access the drain.

Okey, here the conclusion for future generations who might have the same issues:

Fuel tank drain hole was clogged at the metal nipple that protrudes from the back of the tank. Its (barely) accessible by removing the battery and pulling the hose off.  Its the one on the left side (right side has one as well but I believe that is so the fueltank can breath).It takes some fiddling but I could clear the block with a paperclip. Reattached the hose and flushed with some cleaning vinegar to remove left over lime.

Then the high idle. I sprayed carb cleaner in the air hose to the stepper motor, but it still had the high idle. Attached the guzzidiag stuff and did the stepper test. Seemed to function, idle would drop and rise a couple of times. Then I checked the RPM in guzzidiag...and it fluctuates between 1260 and 1280. Meanwhile the tachometer shows 1400-1500, so obviously the issue is with that.

I noticed with guzzidiag that when I start the bike RPM jumps to 1400 for less than a second, then the stepper motor steps in and RPM drops to around 1250. It stays around that, fluctuating between 1250 and 1280. I also noticed that while idling the throttle position fluctuates from 4.6 - 4.7 - 4.8 but never lower or higher than those.

So is this roughly how it should be?

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Sounds normal to me as my revs are around same on dash; it always runs high until initial stop & put back into neutral with clutch; sometimes it wanders a bit up and down and can see stepper 'thinking hard about what to do'.....Overall I wouldn't get too hung up on revs moving about a bit; I only start doing something when it keeps getting stuck at high revs a lot and at that point start thinking about pulling off the throttle bodies and cleaning out all the oil....

paulbrice wrote:

Sounds normal to me as my revs are around same on dash; it always runs high until initial stop & put back into neutral with clutch; sometimes it wanders a bit up and down and can see stepper 'thinking hard about what to do'.....Overall I wouldn't get too hung up on revs moving about a bit; I only start doing something when it keeps getting stuck at high revs a lot and at that point start thinking about pulling off the throttle bodies and cleaning out all the oil....

On another note, while inspecting everything I noticed the hose behind the rear breakfluid canister isn't attached to anything. I'm assuming its supposed to be like that for venting etc, however browsing the parts manual it is listed as a 'fuel pipe'? Which doesn't make sense as I'd (obviously) notice it if a fuel pipe was disconnected.

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I circled it on the photo. The other end is somewhere near the fueltank/airbox but doesn't seem to be attached to anything.

Just a breather for the gearbox, that's all.

Oz1200Guzzi wrote:

Just a breather for the gearbox, that's all.

Great, for once I assumed correctly. Thanks