Air valve

[hoover]

Hi all,
I’ve been having ongoing trouble with my air control valve, this time I’ve completely stripped it to clean and inspect it properly.
I thought a picture of the parts might be interesting.

[OK-944]

I did this (disassembly/rehab) of the idle air control valve (ICV) on my earlier 85.5 (now have an '87), and yours looks similar yet different. My current '87 also has an ICV (located underneath the intake manifold) which looks from the outside exactly as did the one from my earlier car, although I've not taken this later one apart.

But I understand that there is an "auxiliary air valve" on later cars...and that these valves are located slightly differently (not centered under the intake?) than the earlier ICV's. Is this correct?

I'm curious about this because as I was getting my wiring back in place after rebuilding my engine recently, I discovered a wiring connector, very close to my ICV connector on the main harness - which had nothing to connect to...and upon further examination this connector looked like it had not been utilized in any way, at least for some period of time, and I surmised then that this harness might have been assembled to also accommodate a later car - and that the "orphaned" connector was intended to hook up with the later air valve (like yours). Does this sound right?

At any rate...in my case the idle on my 85.5 had been "hunting" for quite some time, so I tested the ICV to determine that it was at fault - then took it apart, polished up the internal contacts (stators) and re-set them to make better contact with the central rotor, and afterwards all was well, idle-wise.

[hoover]

I haven’t seen what you describe as an auxiliary air valve on my ‘89, so can’t help with your query on this matter. I’m not as fortunate as yourself, regarding the end result ; I still have issues with the revs dropping off at idle. Stopping at lights etc, will stall if throttle is not used. Starting from cold is fine, which I thought was the valves main job but a short distance down the road problem can show again, yet at times it doesn’t happen. I’m thinking problem might be elsewhere.

[OK-944]

hmmm...if this is not an ICV/ISV issue, then maybe an MAF issue? Time for the guru's on this forum to chime in!

[hoover]

My S2 has the original AFM unit, maybe I should remove the top and take a look. I’m getting pretty despondent with this issue, and I’m not too confident fiddling around with these components. I used to love driving this car but this spoils the experience.

[OK-944]

Please don't give up! These cars are wonderful (and very reliable) when correctly dialed in.

[djnolan]

Before taking it apart or even removing it from the car, I would try to clean it with some good old fashioned spray fuel system/carburetor cleaner. Spray it in through the Jboot hose connection, let it soak, repeat, and see if it frees up.

[dme]

I've just solved a similar idle problem with my 951. My biggest mistake was not checking some of the simple things on my car first and just assuming it was the Idle control valve (ICV). I replaced the ICV because of erratic idle. It didn't help. Finally, I took the throttle body off the car for inspection. I had a hunch the throttle position switch (TPS) was bad because the injectors were not shutting off at deceleration. I could hear the switch in the TPS click when the throttle was closed and assumed it was working. Well, it wasn't. I took the TPS apart and cleaned it out though it really wasn't dirty. For whatever reason, it started working again. While examining the throttle body I discovered that it was not closing all the way and it was not hitting the set screw stop. Turns out the TPS was misaligned and the micro switch in the TPS was acting as a stop. I readjusted the TPS and the stop screw, put it all back together and so far, it seems to be working correctly.
I've had this car for three years and should have verified the throttle body operation before this, but I looked passed it while working on other parts. My mantra is start simple and cheap and move up from there. I failed on this one.

[OK-944]

I watched a video recently of a guy overhauling the throttle-body/tps - and it turns out if oil ever gets sucked into the throttle body - some of this oil can settle down into the tps itself if its gasket is worn. I did not see this video until after everything was back together after my rebuild - but I should have checked!

[hoover]

Thanks for all the advice being given, I’ll do my best to sort it. I’ve owned it for over 20 years, so it owes me nothing, with 161k miles on the clock. There are things that will need doing before long, a couple of brake pipes maybe, and the clutch has done getting on for 80k. A decision will have to be made soon.

[dme]

The TPS is an expensive yet stupid simple sensor. I used some instruction from the arnnworx site to clean and test mine. Saved me a lot of money.

[hoover]

Thanks, have you got a link ? All I can find on an Arnnworx site is the tools they sell.

[dme]

Here it is.
951 TPS Repair : ArnnWorx Specialty Tools

[hoover]

That’s great, thanks.