Cleaning the CIS Butterfly Valve

Sunroof · 06-08-2005, 05:23 AM

I have the 1973.5T original CIS setup.

Once that air bellows that covers the sensor plate and butterfly valve is off its easy to wipe down the plate, but far more diffcult to clean the butterfly and intake area.

I never ran the engine with the bellows off and have to wonder if it would operate at all! I do not really know its purpose besides sharing air. Help me on this one!

What is the best way then to clean the butterfly without taking the airbox apart and removing the entire system? Can you use a spray cleaner while the engine is running?

Can anyone offer some suggestions on cleaning that unit up while still in the car?

Thanks
Bob

kach22i · kach22i's Garage

I was thinking of just using WD40 or PB Blaster because I'm affraid "contact cleaner" may get into (and would destroy) the mixture control plunger, which I assume should be cleaned while I'm in there.

We need an expert or someone who tried this to chime in and speak up. That's not me, the most I've done is wipe down the inside of the box with paper towels and or rags while doing re-glue of the pop-off valve.

Sunroof · 06-08-2005, 07:13 AM

We will hold fast til that someone with prior experience comes along.......

MotoSook · 07:52 AM

The car won't run without the CIS air boot! It is critical in the air path which causes the airplate/meter to rise which inturn feeds gas to your engine!

With the boot off, you can clean the throttle body with a shop rag wetted with carb cleaner or brake cleaner. You won't be able to clean all of the TB, but holding the butterfly open, you will be able to clean most of it. If you are confortable, you can remove the TB for cleaning, but if don't know what you are doing, you'll be back posting a thread on how to get your car to run right afterwards.

If the TB is really cruddy, be careful you don't force crud into the vacuum ports. Wipe lightly with a soaked cloth and try to "draw" the crud on the cloth....pushing and scrubbing, only as the final cleaning when the metal surface is mearly coated with a thin film.

Sunroof · 06-08-2005, 11:46 AM

Thanks.
So using a spray cleaner on the inside of the throttle body is out?

Bob

MotoSook · 06-08-2005, 11:50 AM

Well, if you spray the stuff in and it drains into the air box...where does the slurry go? It might settle on the bottom and and some might get ingested into the engine....but I'd rather wipe it up and out.

Unlike a carbed engine you can't remove the air cleaner and spray awy while holding the throttle open.

Sunroof · 06-08-2005, 01:55 PM

Well, I learned from this one. Although CIS is a simplified injection system, I never understood all its components. I appreciate the lesson on butterfly valve cleaning and I am glad I came to the board first before I screwed something up. The rag and cleaner are the route I will take.

Thanks for the help.

Bob