Modern Vespa

Early last year I had problems with idle - it started seeking / saw tooth pattern. I eventually fixed it by replacing the throttlebody / ecu. While replacing I compared the old and new and observed the old had a lot of movement in the shaft that has the butterfly and tps whereas the new had none. This was at around 27,000km.

I'm now at 44,000km and it's recently-ish started to often get stuck at a high idle of around 2200-2300 rpm and refuse to come down. On other days it's very very very slow to drop down to the normal 1700rpm. Feeling bad. So I have tried wiggling the shaft and it's now got slack like the original had when it died.

f**k.

all appearances to me are that Magneti Marelli throttle bodies are not robust.


crosslinks:
Saw tooth idle [SOLVED - worn throttle body]
My new throttle body doesn't rattle. UPDATED: dying 🤬🤬🤬

PS before anyone tries to give me advice on how to fix this please read my old thread from last year and all the attempts and fails. Saw tooth idle [SOLVED - worn throttle body]

Throttle bodies shouldn't wear out like that. Something's wrong.

Stock air filter?
Riding in that horrible Aussie dust?

it's the paper filter type that is standard on Asia Pacific HPEs. not the foam filter that most of the world has. so yes stock. yes. lots. and lot's of these road are corrugated

I know Mike Holland has had to replace the throttle body. Quote from a thread a year ago:

Yes, but I replaced mine because of that hesitation/misfire when cruising at 100 kph. Probably a TPS fault.
Maybe your problem is a result of all your country riding, on unsealed roads and such. Too much dust in the air.

my thoughts as well.

I think it's subject to harsh environment is causing premature failure. the dust and dirt and murder on moving parts like that and the vibration just adds on top.

Ponderances & Speculations.
Mostly probably easy to dismiss.
READ ALL BEFORE COMMENTING


* Dust reaching the TB
Reminder in Aus we have paper filter on HPEs not oiled sponge.
Is this paper filter good enough to stop the dust on the unsealed roads I often ride?
Piaggio first started using it with 125/150 so was it designed with only that level of airflow in mind?
Saw a matching aftermarket one the other day with the usual promises (some part of asia - can't remember which).
Could swap the airbox to classic oiled sponge but don't want the low down intake cause of dusty unsealed roads.
There's no seal around the filter where it's screwed into place, surprises me.
Did see the filter extremely gunky from dust + oil first time I opened the box, now I check and replace myself every several thousand kms.
The box itself is often a bit gunky so I wipe it out with paper towel and every now and then I completely remove it and wash it in the sink.
When I added some foam around snorkel inlet it stopped significant amount of the dust from getting into the airbox.
Tube from box to TB often (usually?) has slight film of oil but never seems gunky so presumably no dust getting through the filter just oil from the breather making it through.

* Vibrations
Vibrations are always there, it might rather be the bumps instead at too high a speed (speed bumps, potholes, etc).
What about cobbled streets, popular in some parts of the world ...
Did the firmer suspension I installed make this worse?
Could the throttle cable tension cause issue when vibrating/bumping, if it was ride by wire would of course be immune to cable tension.

* Friction from heat expansion
Could friction of the steel butterfly wear against the presumably softer alloy of the TB?
Old TB did appear to have larger gap around butterfly vs the current one when I installed it, this is why I doubt it's the seals around the shaft.
The intake temp reaches 45-50C on normal cruising and 60C on long rides.
Is the prolonged 60C enough to cause enough expansion to cause friction?

* TPS
Pretty sure I saw the same values on this when swapping from old to current.
Doubtful it's failing.

* MAP sensor
Is that dying?
MIUG3 docs "measures the pressure in the intake manifold in real time"
It affects the injection mapping and is also used for compression stroke TDC.
Might be able to read it using ODBC and compare it to a healthy bike.

* Other bikes
Aprilia Tuareg 660 which is ADV have Magneti - is it a more robust model?
The Apilia SR-GT is sold as an ADV and pretty sure it's TB is a Magnetti (albeit the ecu is separate from tb), but yeah marketing.
Pretty sure I even saw Harleys had Magnetti for a while.



Note: some of the above is based on docs about the MIUG3 and some on MIUG4

continued from previous comment ...

firstly any comments suggesting I stop riding in the country would be unhelpful.

what I'm posting this for is I'm wondering am I going to have to replace my TB every 20,000km or so? ie every year?

is there any way I could reduce the problem (excluding what I said above)

or even resurrect either my old or current tb

I really really really really don't want to get a motorcycle for country riding (multiple reasons)

Pics of paper filter aren't loading.

Nudge nudge.

Part number 1A007327
https://www.sip-scootershop.com/en/product/air-filter-sponge-piaggio_PI007327

(pic from another website for convenience reasons)

My first Vespa's throttle body is also worn.
The butterfly has a gap of 1mm all around.
It has done 45 000kms on tar.
It's previous life was a medical samples delivery bike.

As far as your paper element is concerned, if you are riding on dirt a lot,
I would suggest having two filter elements that you swap out at more regular intervals and vacuum them clean before replacing. We do this on our airhead BMW GS machines. Even just removing the element and tapping it upside down will clear much of the dust after a ride.

And how was that Vespa? Perfect or was the idle high or unstable or?

Thanks to the oil from the breather slightly blackening the filter, I don't think I'd be able to clean the dust off it effectively. But they're cheap so not concerned.

another observation

it now does that burble pop more often when coming off the throttle. typically when the engine is not very warm and from lowish speeds as I roll towards a red light.

reminder: I do have an arrow exhaust (with cat)

Out of curiosity, what is the warranty period on official Piaggio parts. For my car, I believe it's 2 years.

Probably.

First was over 2 years when it died and this one is 2nd hand

a few days ago I [re]installed the malossi lambda emulator and disconnected the battery for > 1hr. Sidn't expect this to improve my tb issue, was just bored and wondered if it would make it act worse.

did a few errands over the following few days, no problem. I was still slowly dropping to normal idle rpm when sitting for long enough.

100km after the install - early in an arvo ride yesterday - it stalled and gave my first cel - P0130 (lambda error). completely unsurprised.

cleared the light when I got home and will ride for a little longer with the lambda.

still trying to make up my mind if it will cause the already non ideal idling rpm to be better or worse.

A couple of days ago I got around to comparing the GTS vs the Supertech wiring diagrams and I think a GTS ecu/tb would just plugin and run fine.

So this makes me think that I should try and get a 2nd hand gts ecu as an experiment because since brand new the gts ecu is half the price of the supertech ecu (for no good reason) and a 2nd hand gts ecu will be easier to find and should be cheapest.

Thoughts?

Please remember that since this would be an experiment I'd prefer 2nd hand. If it does work then I'd be happy to pay full price for a gts ecu


Notes:
* Before someone says "what about the bluetooth in the supertech", well that's handled by the pmp2 module not the ecu.
* could probably also use a Sei Giorni HPE ecu with the caveat that ASR wouldn't work.
* the gts wiring harness has a wire for cel direct from ecu to dash but and the supertech doesn't, instead I believe if monitors the can-bus


gts ecu CM291708
supertech ecu CM291706
ref Supertech HPE VIN and engine numbers

I've seen wartime motorcycles adapted for desert uses with huuuge secondary filter boxes.

What's the dust done to the cylinder?

Well it tried to kill me today by dying in traffic and refusing to start leaving me stranded in the middle of the road with cars going by for 10secs*

Think I need to add a hazard lights switch for the blinkers.



* 10scs exactly from checking the data recording.

It seems to me that if your filtration was the problem you would see a lot of gunk in the throttle throat? Also, it would eat up the rings etc on your motor. Is it possible to re-bush the throttle shaft? I have never seen one but there is definitely no lubrication on the throttle shaft except the bearings are probably oil impregnated from the factory but just like those cheesy DC motors in bathroom fans, eventually the bearings give up the ghost. If you have the old one around, take a look at the throttle shaft and see if its the shaft that has worn or the body itself. You might find a simple replacement if its the shaft?

To see what it looks like watch my old video from last year which was on my old thread https://modernvespa.com/forum/post2546564#2546564

I'm confident it ain't the air filtration (as I did 'fix' that early on as mentioned elsewhere) although it does come up now and then as I mention the different filter style as I ponder why it happens to me and not others (or very few?). imho not the filter.

The shaft and/or butterfly cannot be removed without removing the ecu which ain't possible without permeant damage. So no repairs possible ever, only complete replacement.

Today I was reexamining the old one today and I noticed that while the butterfly is closed that the flow around the edges of the butterfly is every so slightly less if I press the end of the shaft lengthwise from the outside pushing the butterfly towards the ecu side of the barrel (hope that makes sense). I did this test by sticking my finger in from one end of the barrel and placing it over the idle bypass and putting my mouth on the other end and blowing. I could feel on my finger the change in airflow.

Also if I open the butterfly 10% or more then there is significantly more in and out movement of the shaft and a larger visible gap around the butterfly.

One of my theories from before and has become a stronger theory after today's testing is that it's the tension of the cable sorta slightly pulling outwards diagonally a bit that has slowly worn things. So is it the butterfly wearing or the barrel wearing or the shaft seals/bearings? Don't know and since ain't repairable anyway ...

But the "why me?", that's what I do ponder a lot as I don't want this to keep happening

So no comments on trying a standard GTS HPE ECU instead of the Supertech one?

I doubt many people would have done it, so the knowledge base is vanishingly small...

sure I get that, just looking for guesses ideally with good logic behind them

but why would they have different part numbers? that's what puzzles me. the only thig I can think of (clutching at straws) is that it has a 'bike model number' stored in it so that when pads is connected it will say the correct name and also let pads known whether to look for the pmp and dashboard, eg to know if to update the bluetooth firmware in the pmp