[s-cars] Ignition timing issues - I think

[Kirby Smith]

Erratic idle could be caused by the idle stabilization valve (ISV) not
operating smoothly due to deposits.  The ISV is attached to the branch
of the hose from intercooler to throttle body.  It can be removed and
cleaned using spray Brake Cleaning solvent or equivalent.  Do this away
from your paint.  Do not use sharp tools to wiggle the ISV mechanism.  A
soft wood or plastic rod should minimize risk of scratching the parts.

I will leave the other problem to others, but suggest you check all
intake system hoses for leaks, including the one that is hidden below
the throttle body/intake manifold.

kirby 95 S6; 2 x 88 90q

Bobby Richter wrote:
>
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> Hi,
>
> [1994 S4 Six speed, 185,000Km's]
>
> Can anyone help with this? It's driving me nuts.
>
> a/ Car starts fine but the idle speed hunts around slightly (+/- 50
> rpm).
>
> b/ When I blip the throttle the engine revs momentarily drop then the
> revs pick up.
>
> c/ When driving the car feels dead and even though the boost is there I
> have to use 30-50% more throttle than normal to get the same
> acceleration.
>
> d/ If I really go for it (WOT), the engine revs build up and at about
> 5500rpm the car will sometimes jerk badly and I instantly tap off the
> throttle.
>
> e/ If I am driving at about 3000rpm and suddenly take my foot off the
> gas with the clutch depressed, the engine will almost cut out then rev
> then settle at the hunting idle speed.
>
> I have checked the fault codes and it reports nothing. I have used my
> friend's ECU and the car behaves the same.
>
> I thus have a car which still can go like hell but feels dead. It almost
> feels like the ignition timing goes out badly and is retarded to its
> limit. Knock sensor? Crank angle sensor?
>
> Has anyone had the same experience?
>
> Cheers,
>
> Bob
>
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