Idle changes when engage/disengage clutch in neutral

[hoonigan4l]

90 na.. car is old, high mileage and has been mistreated.. I've fixed a few things so far.. plugs, bad coil, bad tps, vacuum leaks, New fuel filter, and a good sea foam douching.. not sure about this though.. the clutch seams to be in OK shape. It doesn't slip under a load and has a decent pedal.. Ideas? Also I have a peculiar problem with the lights. No brake lights, tag lights, low beams or interior lights.. possibly a ground somewhere came loose?

Thanks a lot in advance. New to the Z world.. Nissan sure did put ten gallon of s*** in a five gallon bucket on this one haha. Fantastic car though.

[hoonigan4l]

Sorry for double post, the edit function doesn't seem to work properly on my S4.. It seems to pretty consistently bump the idle up ~200 Rpm when stepping on the clutch pedal. Maybe this is factory setting to help from stalling? Never encountered this before.

[ThisIsSparTTa]

Mine does the same thing. I'm not too worried about it.

[hoonigan4l]

Well that's good that it's not only mine.. It concerns me a little because there is no reason why it should do that. Except for possibly raising the idle to take off. But this doesn't seem consistent with other Z's..

[StigZXTT]

My idle always raises a tiny bit, maybe no more than 100rpm or so, when I step on the clutch pedal. My guess is it's because the weight of the clutch spinning with the flywheel when in neutral is being taken off and the idle then has less load on it? So the engine can then turn over faster? I also always notice that if I'm in neutral and the clutch is pressed in (like on startup), and I release the pedal, the revs drop a tiny bit (again about maybe 100rpm). Hope this helps.

[hoonigan4l]

Thanks for the input fellas.
I also noticed, on cold start, it's about a 250-300rpm drop. When it's warm it might jump 50-150rpm. It is just slightly embarrassing is all.. Pulling up to red light, loud car sounding funny and such.. It may be because my idle is not set properly yet.