normal idle speed and feel in your S4?

[Aspen]

Hi Guys,

Im slowly getting round the car, you know, getting it all to my liking. a wheel alignment, all wheels balanced full clean inside and out. You know the usual.

But before I go fitting the 6 new coil packs in the morning, can you tell me if this is normal please.

My S4 idles at about 650 rpm, it seems very low. And feels 'lumpy' on tick over because of it. almost like my old V8 S5.

What else could this be, or is this just a class effect?

80k on the clock and been driven by miss daisy all its life.... Well, until now I suppose. lol

 

[Aspen]

Could this be a vacuum leak?
Where to start I wonder.

 

[RyanJonS4]

They do idle very low and can be a little lumpy.

The factory crank pully has a rubber damping section in the middle and these have been known to fail and cause a fair bit of damage. That would be my first check.

If the car has been driven by miss daisy, it doesn’t do them any good at all and can cause the old carbon build up around the valves to happen a fair bit faster. This is impossible to investigate without taking the supercharger off though.

 

[Aspen]

Update.

I stripped down and replaced the air filter. It was a bit dirty tbh. And had a good check of all intake attachments for tightness and all vacuum lines.

I then blasted the throttle body valve with cleaner and cleaned that right up as this made a huge difference to my 997. Stuck an inspection camera inside to see if there’s any bios up or oil residue. It looks pretty clean.

The blasted some cleaner through the chamber whilst running the engine, well, just because and then refitted everything making sure it’s all nice and tight.

Then I checked all the coil packs and refitted them.

Weirdly. Huge improvement! Almost as big an improvement as with the 997. Maybe they’re just as sensitive?

 

[scotty76]

Bit late now but mine idles at 700rpm and has always felt lumpy.

 

[V6_Man]

Bit late now but mine idles at 700rpm and has always felt lumpy.

Seems just about right ...

 

[jdp1962]

Bit late now but mine idles at 700rpm and has always felt lumpy.

Same here.

 

[Aspen]

As an update. My huge improvement must have been placebo lol

 

[3Qn]

I just visit an Audi Coventry as I have little problem with my gearbox. When stopping it has motion like someone rear end You, but back to the point Audi picked it up that on idle car is lumpy and it needs further investigation my revs are 650-700 and feels ok same as my mate S5 4.2. When I asked them what it should be they said higher so even so called master technician couldn’t tell me what’s the right revs for idle.