550 idle too fast

Theyuse to idle up to 1500 rpm if not stationary...

 

There is a procedure in the WSM for adjusting idle speed, which should be 1020 rpm with AC on. Page 138 of the one I have and noted in the index.

 

When my 456GT started doing that the thermostat and/or temperature sender generated a "Check Engine" light and a code in short order (a few days later). I replaced both and the fast idle issue was immediately resolved.

Hope this helps!

 

I think mine could do with an internally clean, and from what I have read Carby cleaner is the go

 

Guess what he was correct, I found mine was not returning to the partial open position quickly. A clean and spray with an electrical lubricant and it function on the bench is now smooth and prompt

 

Graeme,

how exactly did you clean it? I'm thinking of doing mine and need some advice....

Stefano

 

I removed both sides. On LHD car it's easiest to remove the LH intake duct withe the idle motor attached.
you can , at least I can remove the other side valve by its self.
Cleaning is easy. I bought some throttle body cleaner.
The rotory valve(viewed via the exit port of the valve) had
Carbon deposits on the valve causing it to be sluggish.
The use a stiff plastic thin scraper, note plastic you don't want score the valve. A piece of clean rag over the end helps.The design of the valve is induction driven, so the can be carefully manipulated open and closed as it's spring loaded. I also cleaned the inside of the connecting plumbing.
I hope this helps.

 

Thanks!!