Stepper motor 101 - (or yet another high idle issue)...

[uncle]

2007 Griso 1100 -  I have the throttle bodies out to clean and try and figure out a high idle when hot (around 2000rpm) - I cleaned them about five years ago and they were very dirty (oily and sooty) not so bad this time as I keep the oil level much lower now.

I have some questions about the stepper motor and whether or not it may be part of my issue. 

1- is the normal state of the stepper motor to be open  (i.e. no power off valve is open) -
2 - if it were 'sticking' open - what is the best way to clean?  (carb cleaner then WD40?)
3 - is there any test to see it it is performing properly?

Then on a related note - can a bad engine temp sensor reading be mixing things up?  Any quick test for a temp sensor (I guess I can hook it up to GizziDiag to get  readings when I get it all back together) -

thanx for any info -
Rich

[guzzisteve]

The early stepper motors had a metal outer body and were problematic, not returning to closed w/temp was up to normal operating. It was replaced w/plastic outer body one that worked.  PN #896540.
I have cleaned them out then fill the hose w/silicone lube spray which helps.
Some owners put a fuel shut off valve in the hose going to it, to regulate the air to off after temp was up. On a cold motor you crack it open a bit to keep your idle up.
Best deal is to replace it w/newer style plastic body one.
There is a test for stepper to increase in the diagnostic software.

[uncle]

Thanx for the reply…  I see the part is around $400…  I may go the silicone lubing route  - and I remember years ago some were putting in a cut-off valve which may be where I end up.

fingers crossed!

[uncle]

Just got it all back together and it started right up and settled into a nice 1100 rpm idle. 

I go for a ride and get it all warmed up...  idle rising.  Get back home to the shop and it's idling at 2000 rpm.   Grrrrrrmphhh....

I get off the bike while letting it idle at 2000 rpm and reach in and pull the stepper motor hose from the air box and plug it up with my thumb.  It settles right down to a nice 1100 rpm idle. 

I guess I will put a 'on-off' valve in line to the stepper until I can figure out if it's broken, stuck or something else causing the stepper motor to stay open...

Anyone ever take one of these apart?

[beetle]

A chap I know has had some success using Liquimoly carb/valve cleaner. He poured about a teaspoon full into the stepper hose while the bike was running. Cleaned the gunge out, at least for a while.

[Bisbonian]

I've had the on-off valve on mine for years, I don't see a downside.

[Stevie88]

I got rid of mine altogether on my 13 Stelvio. Just plug all the barbs and ride her like you stole her.

[uncle]

I guess my stepper motor figured 10 years of service was enough.  Not thrilled with the replacement cost so I went the on-off valve and the bike is back to idling fine when hot again...  Easy enough fix for much less $$$ -