Throotle Body Time

Hi,

Since I cleanned the TBs, when I start the engine (in cold or hot condition), the revs go up to ~2000 rpm for some seconds and then drop down to normal idle (~1200) and stay there. I guess it is the stepper motor adjusting the amount of air in the mixture...
But the bike was not doing this before...Can it be that now there is more air going through the TBs in shut condition?
Does anyone ever experienced this after the TB cleaning?

thanks

Matias,
A GRiSO owner near me who is a long time Guzzi guy but new to throttle bodies bought a 2016 a couple of years back that had 2,000 miles on it. It had already had its charcoal canister removed and I don’t know what else but he told me and showed me that every time he starts his GRiSO up, it goes to about 2,000 rpm before settling back at about 1200 rpm after warm. I asked Pete about it and he told me to check to see that both air bleed screws weren’t left open which made me think of your situation. I suspect due to your diligence this probably isn’t the case. I haven’t been able to check my colleagues GRiSO yet.

Hi John,
I did the TB balancing after the cleanning.
The left airbleed is closed and the right one ~1/4 turn oppened.
It looks like when the engine starts there is more air going through the TBs now (from the gap between the butterfly and the TB walls after cleanning, not from the airbleeds), raising the revs, and in around 5-10 seconds the stepper motor brings it down to 1200. Can this be?...
Question: how do you check if the stepper motor is working as it should?
I believe I saw in the "engine off actors" menu from GuzziDiag come indicators about the stepper...

I’ve already explained how the stepper test works, in our email exchange.

Hi Mark,
You explained to me the "Stepper (idle control)" test on the "Engine On Actors" menu, but I seem to recall seeing some reference to the stepper also in the "Engine Off Actors" menu...cant't confirm it now because to see it you need to have GuzziDiag connected to the ECU...Do you confirm?
While we are at it...Mark, do you know what causes this rev increase in start-up phase?

Thanks

Correction....
Its not on the "Engine off Actors", its on the GuzziDiag measurements (below).
What do these measurements tell, Mark?
[You must be registered and logged in to see this image.]

An elevated RPM at startup, and then settling is totally normal...my GRiSO and Norge both do that. The stepper motor works all the time, not just at startup. How did I learn that...from Mike at MPH after thinking that my stepper motor on the GRiSO was the cause of an error message, only to learn that it wasn't.

By the way, Mark (Beetle) also indicated and you can find the thread buried here in the archives...probably mine, that a Ducati stepper (metal) vs. the Guzzi plastic one is also 100% interchangeable for about 1/3 of the price...there are plenty on Ebay.

Doubtful your stepper is off, but be sure that the airhoses are routed and wrapped and connected properly...

By the sounds of it, it seems to be behaving properly...I'll time my GRiSO and see how long it stays elevated before settling in at idle.

Matias wrote:

Correction....
Its not on the "Engine off Actors", its on the GuzziDiag measurements (below).
What do these measurements tell, Mark?

They are the values the ECU gets from the lookup table to control the stepper. Unfortunately, there’s no feedback from the stepper, so the ECU doesn’t know if there’s a fault with the stepper, or even if it actually moves.

There are only two ways to know if the stepper is working correctly. Use the stepper test and note the changes in idle speed, or listen carefully when you turn the key off. You should be able to hear the stepper whirring as it goes to its default position.

Hi,

OK, I'll do both tests.
If I understand correctly how the system works, I would say the stepper motor is working, only it's default position is not the adequate for the current conditions (cleanned TBs with a bit of wear on the inner walls). Explaining my theory:
- The engine is stopped and the stepper in default position.
- As I start the engine the ECU detects a high idle and orders the stepper to reduce the amount of air in the mixture. It takes the stepper some seconds to do that from it's default position.
- After this correction, the idle stays normal (with small corrections being done now and then by the stepper) during the engine work.
- As I switch of the engine, the stepper returns to it's default position.
- When I start the engine next time, all the cycle repeats.

Is this right?
Is this stepper default position something that is set by the manufacturer and doesn't adapt to the changing engine/TB condition?

Hi everyone,

Short update...
Today I finally was able to take the bike for a 60 km ride, so here's my feedback
- Differently from whatt I said before, with one of Mark's map tweaks and clean TBs, the smoothness of the engine in low revs/almost closed throoltle improved considerably. I'm very happy with that.
- No popping
- Regarding the stepper: I was paying more attention today. When I started the bike cold it went to normal idle directly. With the engine hot (I started it hot for 2 times): the first time the idle went up to 1500-1700 and came down after 5 sec, the 2nd time it went up to 2000+ and it went down after 8 sec

Matias wrote:

Is this right?
Is this stepper default position something that is set by the manufacturer and doesn't adapt to the changing engine/TB condition?

Yes, that's right.

The stepper is not adaptive.

High idle on start up is pretty common and yes, I think it is probably at least in part due to wear in the TB's. My Yellow Bike was prone to it. During the 600 revolution warm up period it would zoom up to around 2,000rpm on start up and as soon as it was out of that it would drop down to about 1400. I replaced the throttlebodies with a new set simply because I had a set I'd bought for myself as 'Spares' because I knew they'd wear out eventually and I realised if I kept hanging on to them I'd probably never use them before I ran out of riding years! So on they went and just like that all the high idle problems went away!

No cold start idle rise, rock steady 1200rpm idle. They also felt like they'd given the bike 10 more horsepower but I think that was simply the result of the fuelling now being spot-on.

As it was the idle rise never bothered me. The high idle irked me a bit, but not enough for me to do anything about it. The one thing it did confirm for me was how absolutely vital decant air filtration is. My thing ran for a few thousand Km with missing drain hoses. That was what caused the damage, I'm sure of it.

Hi,

I am walking on thin ice now, because I am about to say a sacrilege...

It's not something that I would do now, because my TBs are not that bad, and this high idle at start thing may even reduce as some deposits start to accumulate....but....if the internal wear on the TBs would result in an increase of the gap between the butterfly and the TB walls, that would just allow too much air to go through in shut condition (with both airbleeds closed, or one just slightly open for balance), wouldn't a micrometric reduction of that gap using the "sacred screw" be a solution?

Why is it such a fucking problem? Jesus wept. You can move the screw. Knock yerself out! Will it fix the issue of high idle? Maybe, probably not, but it will move the baseline of the entire map! That means that rather than having a tiny inconvenience that means and in reality affects nothing you have ruined the integrity of the mapping everywhere. Will that make a difference? Yes, yes it will. Will it make enough of a difference for you to detect or enough to damage the motor or its performance? Who knows?

Look, you do you, but don't for a second think that others haven't been down this path before and found it to be fruitless and potentially damaging.

Don't do it. I will not be able to help you any further if you do.

I was not considering doing it now.
Just considering the possibility for future TB degradation... But after your advice I will keep those screws sacred

Just consider that the bike is getting older -like us- and small things might change……like us…..
I’ve learned a lot from this thread, so thanks to all.

You are a wise person John, and I should listen to you more...
What can I say....I guess I am a compulsive fixer ....

The GRiSO cleanning the TBs (the good way ....)
[You must be registered and logged in to see this image.]

[/quote]


There are only two ways to know if the stepper is working correctly. Use the stepper test and note the changes in idle speed, or listen carefully when you turn the key off. You should be able to hear the stepper whirring as it goes to its default position.


[/quote]

Hi everyone,
It ain't over yet....
Even though some things have improved with the TB cleanning, there were still some anoying things going on:
- When starting hot, the bike was idling high (2000 rpm) for a while
- While riding or blipping the throotle the engine hangs for a while with a high idle, dropping afterwards to normal idle
- The bike was having a random behavior while riding...Sometimes no pops and good idling, sometimes the opposit...

I was searching on the forum and found some threads relating this type of behavior with the stepper motor, so I went on with the investigation.
- I did the GuzziDiag stepper motor test. I did it with the bike hot, and couldn't notice any change in the idling behavior as the test was running.
- I did the Ignition switch on/off suggested by Mark. I'm attaching a small media file to the post. You can hear a click (the ignition switching off) and after that a noise that I suppose is comming from the stepper. It seems to be working, but it seems also to be struggling....I cannot tell if it is the normal noise, because I have never "met" personally another GRiSO than mine

Next step, I plugged the hose coming from the airbox to the stepper, and also the spigot on the airbox, and took the bike for a ride.
I must say the bike in hot condition works much better without the stepper than with it....No pops, smooth throotle changes, steady idle, no hanging in high idle...
I just didn't had the chance to see how it behaves in couldd condition yet...
So its clear. The problem was coming from the stepper.

I believe the stepper motor is still working (or trying to...) but the valve that controls the airflow to the TBs is probably dirty and partially jammed, delaying it's reactions and probably not being able to close completely.
My stepper motor is the metal one.
Questions (as ever...):
- Is it OK to spray down the stepper/airbox hose some Carb Cleaner? Can it be done with the engine running? The spray can I have says it can, but I'm affraid it can cause damage/pinging in the cylinders...The feedback from the experts here will be highly appreciated...
- I believe I saw in a thread someone saying that was able to disassemble the valve from the motor...Can it be done? Will the ECU still find the right stepper position after that?

As allways, your help will be much appreciated.

stepper noise

That stepper sounds normal.

You can spray that stuff with the engine running. I've done it.

I've done as much cleaning as I can with a carb cleaner spray nozzle,but I've never actually removed & cleaned my stepper or the TBs;nor do I intend to while the bike is running great.

I ride mostly on back country roads;so I always just tolerated the hanging high idle & got used to it.

This summer,after the GRiSO being off the road a couple of years; at the very first stop light on my first test ride on my 1100, the stepper motor pulled that hanging high idle crap & eliminated completely all my expected engine braking power.

I had plenty of buffer space around me,and I really wasn't in danger but it was disconcerting that the stepper motor had control of my motorcycle,not me.

I disconnected the stepper motor & capped off the air box that afternoon;what a difference.

I love the feeling of working through the gears with the throttle & engine;I hadn't realized how much that hanging idle changed the character of the bike;much smoother gear changes both up & down, & I love having 100% of available engine braking power back.

At the same time that I eliminated the stepper issue,I changed to Bulldog9's suspension settings.

Those 2 changes for me;were both significant improvements to my GRiSO.

fwiw fyi ymmv

Hi Mark
OK, I'll try it

Hi BOCX,
I know what you mean...
These things sneak on you gradually, and either you don't notice or ignore and adapt. Until one day, when you have a glimpse of what used to be, you understand what you were missing and don't want to go back.
I was very satisfied yesterday with the way the bike was behaving with the stepper plugged. If she will be able to hang on idle with a cold engine (the temperatures here in Portugal are not that low...), I might very well leave it like that. Must try it.
If she don't it will anoy me...I like to start the bike, take it out of the garage, and let it idle for a while while I put the jacket, helmet, and gloves on...Don't want to have to stand there nursing the throotle.

If the cleanning will do something I will let the stepper do it's thing....I hate to have bits on the bike that don't work as they should....compulsive fixer:geek:

Otherwise, the petcock valve used by some guys in the forum might be a possibility...

Matias wrote:

I like to start the bike, take it out of the garage, and let it idle for a while while I put the jacket, helmet, and gloves on...Don't want to have to stand there nursing the throotle.

If the cleanning will do something I will let the stepper do it's thing....I hate to have bits on the bike that don't work as they should....compulsive fixer:geek:  

I should have mentioned that in my post.

That is the key difference;my solution of eliminating the stepper isn't a good solution or fit for everybody.

My bikes lead a pampered existence; I never do real cold starts & after starting the GRiSO @ around 30? seconds, I have the time to be there with my hand on the throttle to bump the idle up a bit for a short time until the engine warms up;doing manually what a stepper motor will do,,,

Matias wrote:

I like to start the bike, take it out of the garage, and let it idle for a while while I put the jacket, helmet, and gloves on...Don't want to have to stand there nursing the throotle.

If the cleanning will do something I will let the stepper do it's thing....I hate to have bits on the bike that don't work as they should....compulsive fixer:geek:  

I should have mentioned that in my post.

That is the key difference;my solution of eliminating the stepper isn't a good solution or fit for everybody.

My bikes lead a pampered existence; I never do real cold starts & after starting the GRiSO @ around 30? seconds, I have the time to be there with my hand on the throttle to bump the idle up a bit for a short time until the engine warms up;doing manually what a stepper motor will do,,,