P80 Idle Control slide or IAC 9454745 Cleaning

[jreed]

It got warm here a couple of days ago for the first time this year (~80-85F) and our '97 855 GLT Volvo at 155k miles suddenly started to have a wandering idle speed and stalling at idle, but only when the car was fully warmed up. The stalling symptom was worst right after restarting the car after it had been running for a while (hot start). I first tried disconnecting the MAF but this did not change the wandering idle and stalling. So, I read up on stalling and rough idle on MVS, found a good post by Ozark Lee (https://www.matthewsvolvosite.com/forums ... =1&t=17425) and so decided to remove the IAC and give it a good cleaning. Since there wasn't already a good illustrated write-up, I took some photos along the way:

Step 1: Remove the throttle cover. This requires a T25 screwdriver to loosen the screw on top. When you remove it, the IAC is visible underneath.

IAC valve under the throttle cover

Step 2: Disconnect clamp. I used a sharp flat blade screwdriver to pry off the Oetiker clamp holding the IAC hose to the vacuum nipple (I removed the other two Oetiker clamps on the IAC later, after pulling it out of the car). Then I pulled the IAC hose off of the vacuum tree.

Screwdriver prying the Oetiker clamp loose from the IAC-Vacuum tree hose.

Step 3: Disconnect the electrical connector on the back of the IAC. Loosen hose clamps at throttle and intercooler and pull hoses and IAC from throttle. There is a black rubber collar around the IAC valve that has two ears underneath that can be squeezed together to release the IAC valve from support bracket.

IAC and hoses after disconnecting electrical connector and hose from throttle.

Step 4: Remove the Oetiker clamps at the IAC connectors. Inspect and clean internal plate. My IAC valve was original (dated '96) and had never been cleaned as far as I know. There was a lot of yellow and black varnish on the plate that needed to be cleaned off. I used MAF cleaner (hexane) which was not very effective at dissolving the varnish. I used cotton swabs and a flat screwdriver blade to wipe and scrape the varnish off and used the MAF cleaner to flush away loosened deposits. I think the varnish had built up to the point that it caused the IAC valve to stick or respond slowly, making the idle wander and the car likely to stall. If you twist the IAC in your hand the plate should rotate freely.

IAC valve with ~15 years build up of varnish (pre-cleaning)

Step 5. After cleaning, twist the IAC to make sure the internal plate rotates smoothly without sticking or binding. During reinstallation I used new hose clamps to replace the three Oetiker clamps I removed. While I had the intake hose removed from the throttle, I took the opportunity to clean the throttle plate. After putting the IAC and hoses back together, the car is running well again.

IAC valve after cleaning.

This worked great for me and was a lot cheaper than buying a new IAC (~$200). If I had to do it again, I would probably have bought some more powerful solvent like throttle body cleaner to make cleaning out the varnish a little faster and easier.

[matthew1]

Beauty tutorial, great photos. Thanks Jreed. This is going in the VRD.

[TravBickle]

I need a little help with this. Are the two tubes/hoses going into the IAC supposed to be hard as rock and/or brittle? Mine are and I had to stop the job for fear of cracking them. I think they need to be replaced so my question is are they a specialty item or do I just need to get the right size and what kind/where from? For the sake of the forum, let's say I am decent with a wrench but illiterate when it comes to car vocabulary so I am looking for specifics. In other words, I would like to buy/order these hoses immediately so again; what do I need? and can you recommend clamps also? I owe more to this forum then just my one thank you so far (fuel pump replacement), so at some point I will try to contribute the plethora of experiences from the last 3 months.
Next steps: Clean IAC, Clean Throttle Body, Clean Flame Trap, Replace Cap & Rotor (Just did plugs and wires), Fix Rear Washer Sprayer . . . And I think it posts automatically but this is for a 1995 Volvo 850 Non-Turbo. Thanks all.

[erikv11]

Hoses: They are not supposed to be hard as a rock or brittle. They are rubber. Sounds like they need replacing. Specialty item.

You want idle control valve inlet hose and idle control valve outlet hose. Here are some prices and part numbers for your vehicle: http://www.fcpeuro.com/Volvo-parts/850/ ... &year=1995. Going to run you about $35 + $10, no idea why they are so different in price.

You won't likely find these at a generic auto parts store, and if you do they may be low quality junk that needs replacing again in a year. So I would order them but you never know, good luck if you try to shop around locally. Heck the FCP prices aren't much from list, i would try calling the dealer and see what they want for them. That one hose is $35 I don't even trust they have the right one - at least at a dealer you can match it up with the one on the car (drive down there).

Regular, screw-type hose clamps will do fine for this application.

[TravBickle]

Thanks Erikv11. Exactly the info I needed and thanks for the advice. I want to do it right so might try the local dealer if I can get to it tomorrow. I'm a new Volvo owner, but obviously not of a new Volvo, and it's already starting to feel like an obsession... is that normal? Ok, I'll try to update when I have some news.

[jreed]

The hose clamps I used to replace the Oetiker clamps were AWAB brand, with diameter ranges of 18-28mm (qty 2) and 24-34mm (qty 1). I got them from the dealer.

eEuroparts has similar ones here that will probably work as well:
http://www.eeuroparts.com/Main/PartDeta ... ?id=988024
http://www.eeuroparts.com/Main/PartDeta ... ?id=981707

[TravBickle]

Thanks. I did order the hoses through the dealer for the reasons ErikV mentioned; close in price and I can drive over there when they get them in a day or two. So I will likely ask for the clamps you mention then. I'd prefer them to the Oetiker for sure. Oh, email just came saying hoses are in already. Sweet

[CTHarris88]

I've had my 850 for 3 weeks now. Drives fine. But i am having this problem. CEL is on and reading P0171. Bank 1 system too rich.
My family mechanic is saying it's an o2 sensor. He also told me he needed to call a guy he deals with when he gets european cars to talk to him about it. 2 weeks later I havent heard from the mechanic. I called today and he told me he hasnt talked to the guy. Not sure what this place is doing. What i am sure of is my car is sometimes stalling when idling (at stop signs and lights etc.) It sounds as if its skipping when in idle. I'm scared, this is my first car and im in love already. It's such a nice ride, i just dont want matters to get worse. Should i try cleaning the IAC? What will i need to go about doing so?

[erikv11]

a p0171 is almost always a bad MAF or a vacuum leak between the MAF and the intake. Unlikely, but possible, that the problem is an O2 sensor. I wouldn't use that mechanic for your Volvo.

Test MAF: try unplugging the MAF. If the car runs better, then you need a new MAF. Aftermarket replacement will not work, you need a unit that is Volvo- or Bosch-branded (same thing).

Vacuum leaks: get a can of starting fluid and spray it on the various vacuum while the car is idling. If the idle surges, you have found your leaky hose.

My money is on the MAF.

EDIT: it doesn't hurt to try cleaning the IAC - that is basically free and your 96 probably needs it anyway.

[erikv11]

One other thing: the first place to check for a vacuum leak, is the rubber elbow on the passenger side end of the intake manifold. You will need a flashlight to see it, it is sort of tucked behind the power steering pump. Very common failure item. If it is rotted out and falling apart, then the car probably needs a PCV job too.