PFDGSB

So I cleaned my ISV last night (97 C4). It was successful and I did notice a cleaner idle.

The process took longer than it needs to. While it looks real accessible, it's a bit of a pain to get the rear hose off. In my opinion, it's was even tougher getting it back on.

After it's done, my hunch is that leaving it connected, removing the front hose only (takes 30 seconds) and spraying some carb cleaner in there would fix all but the worst cases.

When it comes time to do it again, I'll be spraying cleaner from the front, letting it dry and going for a ride. Just a thought for those looking for an easier way. . .

AZ993

Nice! That was one of my first DIY projects last year when I got the car. Then it was onto: door pocket reinforcements, TORE LED external lights, morimoto projectors, fixing the front seat rocking on rails... the fun never ends!

From what I remember, a few of the DIY threads on this suggested switching the clamp orientations so they’re easier to access and unscrew the next time around.

Also I think another recommendation was a bit of soapy water on the external body of the ISV when you go to slide it back in.

Endoman

It's a lot easier on a Non-Vram. When I fitted the Vram manifold I did a couple of things to make access easier. I put an extra spacer in the engine mounts (RS) to lower it 5mm and removed the sound insulation ( not all will want to do this) the bare studs were covered with rubber bungs to save my knuckles. It also made it easier refitting the airbox. removing the insulation did increase engine noise in the cabin and heat transfer but I can live with it.

pp000830

It is a bit of a pain to get it out and back in.
A good thought to not completely remove it. This also avoids detaching the electrical connection.
On will still need to check that the internal valve rocks back and forth freely. Maybe this can be done in place by gently touching the internal part with a screwdriver after it is cleaned and see if it wobbles back and forth freely.

Jay777

Can anyone describe the symptoms that indicate an ISV cleanout might be needed? My 97 has what I first thought was a lumpy idle but I've grown accustomed to it like I have the gas/oil smell.

dmaxd03

If you don’t know the last time it was done, you are probably due. It’s a relatively simple procedure, except for the difficulty of getting the isv back in. Be prepared to be frustrated. It took me 30 min of messing with it, then it just fit. Still not sure why it finally worked. Not so scary I wouldn’t do it again, but I would make sure I am not on a time deadline.

My symptom was a low idle, stalling at stops when the car wasn’t warmed up. Isv fixed it.

PFDGSB

@Jay777 Consider getting some carb cleaner, remove the front hose (easy to do) and spraying some carb cleaner in there (engine off). Let it be for a few minutes to dry (carb cleaner evaporates quickly) and see if your if your idle improves.

There is a little valve in there almost like it's on a pintle (although it will be horizontal the way you'll be looking at it). Take something small (small rubber hose?) and move the valve - it should move pretty freely after you clean it. If it does, it's likely that the isv is not too bad. Just MHO.

Jay777

Good info dmax and PFD. I’ll put it on the “to do” list.

IainM

I'm probably OCD and AR but when cleaning deposits by using solvents, I like to flush the crud out rather than relocate it where it'll probably just go right back.
Then again, if it's easy to spray, you can do it as often as you need to

JasonAndreas

Before you use carb cleaner, check the MSDS to be certain that it does not contain acetone.