What is the CIS valve?

Ian Garrard · Post by **Ian Garrard** » Sat Dec 20, 2003 2:22 pm

Can someone help me? About 6 months ago, I had the usual 480 problem of an erratic idle speed. All my attempts to fix the problem failed, so I finally resorted to the local Volvo garage who charged me the best part of Â£100 for an hour's work, described on the form as "Cleaning of the CIS valve". Well, the idle speed has gone erratic again, and I would like to clean my own CIS valve this time! But what is it, what does it do, where do I find it, and how do I clean it? I have a moderate understanding of modern cars, but have not heard this term before. Needless to say, the Haynes manual is no use. Can anyone help? Thanks.

Website · Post by **coyote1980** » Sat Dec 20, 2003 2:32 pm

I'm not too familiair with all these valves either, but I found the following through Google on another Porsche

Continuous Injection System (CIS) Valve

It appears to be some sort of saftety valve that prevents backfire. But I'm not sure this will help in locating it...

Ben Harris · Post by **Ben Harris** » Sat Dec 20, 2003 5:54 pm

I've seen references on Google that imply that the "CIS Valve" and "Idle Control Valve" are one in the same thing (particularly this newsgroup article which was for another Volvo). If this is the case, then all Volvo probably did was to clean the "idle control valve", which is a fairly common topic on here. You can probably find all the information you need through the search facility on the forum. Also, let us know which model 480 you have, and how old it is because the idle control valve has moved around over the years and with different flavours of the engine.

Ben.

Ian Garrard · Post by **Ian Garrard** » Sat Dec 20, 2003 9:01 pm

Thank you for the help. I have a few leads to investigate now. On the Bosch website, I found some information on the Continuous Injection System, which seems to be the meaning of CIS (well done Coyote1980). However, I still don't understand which valve requires cleaning. By "Idle Control Valve" are you referring to what the Haynes manual calls, the "Idle Speed Regulating Valve"? If so, the manual says it can only be replaced, not cleaned.

The car, by the way, is a 1990 Volvo 480ES with a B18FP engine and I think a Bendix 3B engine management system, though I could be wrong about that last bit.

Ben Harris · Post by **Ben Harris** » Sun Dec 21, 2003 12:08 am

Ian Garrard wrote:By "Idle Control Valve" are you referring to what the Haynes manual calls, the "Idle Speed Regulating Valve"? If so, the manual says it can only be replaced, not cleaned.

That's the one. It's not something that's particularly easy to repair/clean, but it's certainly very possible to do yourself. If you choose to replace it, if memory recalls, you'll be handing just over Â£100 to Volvo for the part alone. Unfotunatly, I don't know where it is on a B18FP engine, but I'm sure someone who does will be along shortly (Volvofox?). Once you've identified it (it's cylindrical, with two hoses going to it, and an electrical connection - here's the one on my B18E engine, to give you an idea: picture), you can remove it and then the simplest way of cleaning it first of all, is probably to spray some WD40 through it, and clean out any gunk inside it that's visible without taking it apart. All it is inside is a stepper motor which opens and closes a valve between the two pipes, to regulate the amount of air allowed to pass through. I'd try this first, and then once you've cleaned up any traces of WD40 left inside it, put it back on the car and see if it's made it any better.

If that hasn't made any difference, your next step is to actually dismantle the thing itself and make sure it's properly cleaned inside and put some very VERY thing oil (Volvofox recomends sewing machine oil) on the top of the motor, where it turns. Before you open it up though, use something like a chissel to put a mark on the two bits of metal which will be separated when you open it, so you can put it back together in EXACTLY the same place. All you need to do to open it is to carefully use a screwdriver or other strong tool, to prise up the little metal tabs which hold it together. Once you've done this it'll simply pull apart (into two pieces - no fiddly bits to fall out, don't worry!). I must stress about the chissel mark though, because if you don't get it back together exactly right, you can see some very strange things from the idle like, continuous revving between 500RPM - 1500RPM, as an example!

Good luck!

Ben.

volvofox · Post by **volvofox** » Mon Dec 22, 2003 12:32 am

can't CIS mean someting like Continious Idle System ?( just guessing), so the idle valve everyone is talking about.

They don't last very long, especially as the air is sucks is dirty and oily (wear leaks?) as mine.
2 years ago i "uncanned" the steppermotor from the valve and cleaned it all The valve it selves can be gently and carefully knocked out and cleaned. (driverpin on the axleshaft, remount:donot knock all thge way, see it turns, and remount the correct way) Use lots of seweing machine oil. 2 years ago great results. few weeks ago the same job needed, bad results, second try: my valve became (to) slow I am planning to buy another.

I see it this way : did i replace it 2 years ago it was broken too now, so i have saved some like 150 euro's ex 20 % vat.

Tip : call a sertified bosch carparts dealer and give him the number on the sticker. Compare to the volvo prize, big chance there is a crowbar load of difference

pol · Post by **pol** » Mon Dec 22, 2003 12:41 am

Didn't read all these posts, but i would have guessed CIS to mean constant idle speed or something like that. Probs just the usual idle speed reg thing..

pol

Ian Garrard · Post by **Ian Garrard** » Mon Dec 22, 2003 3:20 pm

Thanks, Ben Harris, for the description and picture of the Idle Control Valve. There is something that looks just like that right in front of my B18FP engine so I will certainly have a good investigation. It certainly sounds like the sort of thing that could cause idling irregulaties.

I was going to look at it last night, but my door jammed and I could not get out of the car! (I've put a separate posting describing what happened.) This was obviously a slightly higher priority to work on. Unfortunately, my garage is not heated so by the time I had finished that, I was in no mood for takling Idle Valves. But I will get round to it soon, and will let you know the results.