Tremelune

I have an '84 with a 3.6 out of a '95 993. When I start the car cold, it will not idle without a bit of gas for a minute. When it's warmed up, it's fine, but does have a bit of surging/roughness. Everything behaves phenomenally off idle.

I did not do the swap myself, so I am not certain of exactly what I'm working with. I have what I believe to be a 993 Mototronic unit under my seat, an '84 DME relay next to that, and a conical air filter in place of the stock unit. I do not know what a WUR is.

I pulled the ICV, and the inside of it was completely black with soot. I could feel the valve move, but softly and slightly.

I put it in my ultrasonic cleaner with some Simple Green until the water stopped getting darker...It was black and nasty after about 30 minutes. I sprayed it out with brake cleaner until it was shiny silver and the valve moved with no resistance at all.

Put it back on the car with the arrow pointing from the air filter to the intake manifold, reconnected the wires...

No real change. It won't idle on startup. After a minute of throttle, it will idle smoothly at 1000rpm, though. When warm, it usually idles between 1000-1100rpm, with 50-100rpm surges in a rhythm.

Quadcammer

did you unhook the battery to let the computer relearn?

How long have you run it after Icv cleaning?

You don't have a WUR with this set up.

nine9six

...but for future reference, a WUR is a warm up regulator.

Your issue sounds like a vacuum leak, FWIW.

Tremelune

...Wha? None of the ICV cleaning threads I found mentioned a battery or idle reset...I am sort of seeing this come up in the lightweight flywheel threads though...Is there an official procedure for this?

I drove it a dozen miles or so, just to make sure the motor got good and warm.

Quadcammer

at this point I'd drive it for a while.

then again, looking for vac leaks couldn't hurt.

My buddies car idled very strange after the ICV cleaning, but we also had a disconnected SAI vac line, so that probably contributed.

geolab

1- ISV must not be cleaned with brake cleaner, the axles of the inside flap are surrounded by felt, and felt drinks cleaner and dries.
respray wd40 inside. hand dry and install
993 engine idles around 800, how is yours idling normally at 1000 ?
If it idles very rough until warm, does the rpm settle at 800 ? or 1000 ?
where is the air temperature sensor that plugs in the original airbox base ?
thnx

NYC993

^^^It took a good of couple weeks for Idle to go back to normal after cleaning. First time it was idling at 2k rpm jumping up and down. Then it would stall couple times randomly. Couple weeks later it was all normal.
Mine is '98 though and I have LWFW.

pp000830

Make sure none of the vacuum actuators on the engine are leaking as they can introduce a large leak beyond what the computer can compensate for, make sure your ignition caps and rotors are clean.

earossi

+1 on a vacuum leak.

Aussie Alan 993

From what I have read, the MAF sensor doesn't like cone filters, especially if they are the oiled type.
For what it's worth, cleaning the MAF is quick and easy and good to rule out.

Just be careful, the sensor itself is VERY fragile. I wrecked mine and had to replace it and I was being careful. Just use MAF cleaner spray and no rubbing with cue tips or the like.