1995 964 154,135 miles

The ol' girl has developed a very rough neutral idle the last couple of days. No other symptoms. Starts fine, plenty of pep, idle smooth in drive, very rough in neutral. Listened to the exhaust, no dead cylinder, no MIL. Sometimes she idles smooth in neutral but once hot, she idles rough. In fact, she will idle smooth and then you feel the instant change to rough idle.

We bought her used with 109k miles on the clock. I'm sure the throttle body has never been cleaned. The TB looks pretty bad on the outside (oily grease).

Are there any do's/don'ts from folks that have cleaned her out?

Does regular carb cleaner work o.k.?

Any thoughts are always appreciated.

DEWFPO

The thought did cross my mind about a possible intake manifold leak but the rough idle isn't there all the time and you can feel it 'kick in' once it reaches a certain temp.
--
1998 S90 071,245 and 1995 964 154,100

Dear dewfpo,

Hope this finds you well. Also clean the Idle Air Control Valve, to eliminate it, as a source of rough idle. See post above or the FAQs (Hovonogila) for a procedure.

Yours faithfully,

spook

1. Use throttle body/fuel injector cleaner vs. carb cleaner. There is a difference.

2. Get a new gasket before starting. Replace the gasket whenever you take the TB out. They're about $1 and it's not worth saving the $1 if a vacuum leak at the gasket joint kicks your butt even once.

3. Take your time. Use an old toothbrush or a fancy camel hair brush from ipd. The TB doesn't care. You don't have to scrub, but if you have built up grime, let the cleaner do the work. Keep it wet and brush gently, it will come clean.

4. Admire your shiny clean TB when you're done, the make sure the vacuum ports are clear before reinstalling. They can clog up too.

HTH

someguyfromMaryland

tip brake cleaner in an aerosol comes with a 'straw' like wd40...use this to clean the vacume ports - just sticj the straw in and blast away!

(ps do it outside and hold your breath that stuffs nasty!)