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Re: [T3] Idle question follow-up - a little long


On 10 Feb 2003 at 8:55, Roush, Norman wrote:

> Here's my situation:
> 
> 1968 Squareback w/FI all stock
>  Start fine
>  Idles @ 1100-1200 when cold
>  Runs fine
>  Idles @ about 800 when warm for a while
>  Then drops to 600 jumps to 1000 and drops to 800 again 
>  But still runs fine and smoothly
>  At night I do notice the headlights dim and brighten with the idle fluctuation
>  Points/plugs/trigger points/timing/value adjustment all OK Check fuel pressure
>  some time ago but was at 28-30 lbs Any ideas?? Throttle switch, recheck fuel
>  pressure?

Looking at this, I think that almost everything is working correctly. I suspect 
that you have some fault that lets one cylinder miss occasionally and that this 
makes the RPM drop momentarily. There are several possibilities:

First I would check all the plugs and plug wires. Maybe the cap and rotor. You 
could put an inductive timing light on each SP wire in turn and just watch to 
see if you see any missing flashes when the RPM drops. This is slightly more 
likely because the spark is hotter at idle, because the dwell time is longer.

There is also the possibility that the injector connectors are not making good 
connections, although you would also feel this as a miss at speed.

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA


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