[SILVY968]

In the last few weeks I have noticed that the idle, especially when cold, is hunting and not very smooth. Between 800 and 950 with 2-3 second "hunt" intervals. In other words, the idle goes up and down with a somewaht, yet not exact cycle of about 2-3 seconds.

Changed plugs...same
Changed rotor and cap...same
Cleaned MAF....same
Now I am thinking about the spark plug wires and the injectors.
First question is can you use a resistance meter to check the plug wires for a "bad" lead?
Second question...is there any way to check the injectors without R&R? I am a religious user of gas with Techron.

Any help would be appreciated.
Brian

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[Kim]

There is an idle control valve or switch. I replaced mine and it solved that problem.

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[Jamie '92 968]

Brian,

FYI,
I have exactly the same thing going on with my car.
I cleaned the MAF, replaced the cap and rotor, and changed the plugs.
I also replaced the spark plug wires and had the injectors cleaned.
No change in the idle (though otherwise, the car runs MUCH better).

I've read a few things recently about the Idle control valve that Kim mentioned.
This is now my prime suspect.

Kim,
Any guidance you can provide on how to replace this part?
Was it an easy DIY?

Thanks,
Jamie

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[Johannvb]

As far as I know the temperature sensor can also cause idling issues when cold.

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[sstman]

The Idle control valve, is the prime suspect in my experience, not a cheap part this side of the pond!, but a good squirt of MAF cleaner sorted my erratic idle, no problem.

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[Jamie '92 968]

sstman,

Can you describe the procedure of cleaning the idle control valve?
Where is it located? Does it need to be removed?
Is this an easy DIY?

Thanks,
Jamie

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[sstman]

Here is the item from the PET, Item '17', I removed the unit from the hoses, and using a 'MaF' type cleaning spray, gave the unit a good blasting, they tend to gum up with sticky deposits from the airbox, especially if you are using a K&N, type, oiled filter element . make sure the apertures are good and dry with some rags, and /or cotton buds. and let the unit dry completely before re-installing.

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[SILVY968]

I found the idle stabilizer by going thru the PET last night. The unit does not seem easy to get out from under the intake manifold. I'll pull the hoses and the electrical connector tomorrow and try the MAF cleaner. I checked the #15 plastic elbow an it had quite a bit of black deposits in it, so I am sure that the whole assembly is dirty.

Today I adjusted the idle cable setscrew, at the underside of the throttle body and got me idle speed up about 400-500 rpm. It is now at about 900 and drops to about 825 to 850 when the AC compressor is on.

I also sprayed a water mist into the intake.

Both made a nice change. I'll report after the stabilizer clean out. I wish my fingers were smaller, my garage was brighter and my eyes were better!
Brian

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[Kim]

I just pay to have that stuff done. Don't really know where it is. The repair was part of some other stuff that I had done all at the same time. I just know that it helped a lot.

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[Jamie '92 968]

Brian,

I see what you mean about getting to the idle stabilizer.
Looking forward to your report.
Pictures?

Jamie

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[SILVY968]

Kim,

It is a bronze colored cylinder, about 2" in diameter, that is under the intake manifold, just behind the throttle body. It has 2 black hoses attached to it. About 1.25" in diam. and an electrical connector coming out of the back. It mounts to the underside of the intake manifold with 2 bolts and is clamped into its holder. The PET shows it vertically, but it actually mounted horizontally.

The hard part seems to be removing the hose that feeds the intake manifold.

Jamie,

It looks way better in the sunlight instead of the garage. I will try and get some pics. It seems that it must be removed to clean it properly and get all of the MAF cleaner out. I got the front clamp done but the rear is a bit tougher. I think that I can remove the electrical connector and undo the bolt that holds it into the mounting clamp. I just need a bit more space. The best place to get at things seems to be from the top...I hope so.

Brian

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[Johannvb]

I have submitted a DIY to the administrators. Once it is approved it will be place in the DIY section.

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[Jamie '92 968]

FANTASTIC!!!
Looking forward to seeing it.

Thanks Johann [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Jamie

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[968forums]

it's up

http://www.968forums.com/index.php?showtopic=8560

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[SILVY968]

Great job!
Brian

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[Jamie '92 968]

Brian,

Have you done the procedure yet?
What were the results?

Jamie

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[SILVY968]

Jamie,

Went to 'Vegas for the SEMA show. It is on the list for this weekend. Not quite sure how to contort my body to get to the clamp on the tube that goes to the intake manifold.
Johann, I am thinking that after you remove the electrical plug at the end of the unit, that loosening the clamp bolt might get the unit out. Might be easier than removing the bracket from the intake manifold.

Damn Germans must have mirrors on sticks and small, yet strong hands!
Brian

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[Johannvb]

Brian,

That was my initial approach as well, but the pipe leading from the valve to the intake maniflod is very short and does not allow for enough lateral movement.. Basically it will not allow you to slide the valve through the clamp. But if you find a way please post it, anything that will make this job easier will be a great help.

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[Jamie '92 968]

Brian,

I had the same thought about sliding the valve out of the clamp, but came to the same conclusion as Johann when I was in there.

The hose clamp on the tube going to the intake was one of the more challenging hurdles.
My clamp, original factory clamp, was aligned so that I could get a long thin screw driver down from the left side and under the overlapping end of the clamp to pop it off. I had to do this mostly by feel, directing the tip of the screwdriver with my right hand around the right side of the manifold. It also helped to get access once the you get the valve clamp off and can move the valve around a bit more.

Hope this helps.
Good luck this weekend.

Jamie

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[SILVY968]

Jamie,

Well that was fun! lol

The OEM clamps are tough to get off, but possible.

Johann was correct with all of the info. I did not disconnect the battery...forgot.
The toughest bit was putting back the rear bolt on the bracket...no room, and if dropped, engine cover off time, but I was careful and it paid off. no engine pan removal required.

The hose from the value going to the manifold came off with a bit of a twist and pull, not as hard as I thought.
Replaced all of the hose clamps with worm gear type. I believe they were 1.5" dia.
The valve was DIRTY, as were all of the hoses and the plastic right angle pipe. All cleaned up easily with MAF cleaner.

I misunderstood the DIY when it said do not use MAF cleaner on the short hose, and thought it meant to not get MAF cleaner into the outlet side of the valve. It soon became evident when I sprayed MAF cleaner into the "vane" side of the valve and it poured out of the other side. Oh well, it isn't the first time that I have misunderstood instructions.

Anyway, I put it all back together and turned the key.
"CHECK ENGINE" came on and she died after a second or two and would not restart.
I checked the electrical connections for the valve, TPS and MAF by pushing them all in.
Tried again after 5 minutes and she started right up.????

As I was removing electrical connectors in the dis-assembly phase, I noticed that ALL of the boots were brittle and had some cracks. Plastic after all the heat and years is on its' way out. Be aware.

Went for a run, up to operating temp, pulled to the side of the road to let her idle.
I would say that she still hunts, but only a needle width instead of about 100 rpm.
She seems to be smoother, but the engine still has a slight movement, but she has been this way for so long, it is hard to say if this fix has brought her back to stock. If I has to guess, I would say it is 80% better. I will take my 13 year old out for a drive tomorrow and see what he says.

<b>I am pleased, and would recommend that we all clean out the idle stabilizer valve due to the amount of air that has gone through it by now. </b>

With the DIY from Johann and lots of light, this should take about an hour with minimum tools and talent, just go slow and don't drop anything! Thanks Johann for the excellent DIY, I don't know how you got some of those pics, your camera is obviously smaller than my head.
Brian

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