fullquack

Hello gents,
Seems me car has started a new trait. Only after the car is up to full temp, it wants to idle at 1200rpm. I have it set at 1000rpm as standard.
What it does is this, while driving, I come to a stop sign or red light, the idle drops to 1200 and stays. If I pull the idle down to 1000 rpm by dragging the clutch, it holds there for maybe 5-8 seconds, then very slowly climbs again back to 1200 rpm. Although sometimes the idle stays down, but only until the next stop light.
This is somewhat intermittent however, I might go a day or two with now issue or it will happen all week, then the next week no problem.
The only thing I've kinda noticed is that it starts doing this everytime I get stuck in stop & go traffic. But never does it on the morning commute when I have open road. Could it be a heat issue, where a control unit simply gets too hot and then won't behave again until it completely cools down???
I've checked the obvious places for vacuum leaks, looked at my intercooler seals, did the propane check around the intake manifold while the car is running, checked the air flow plate for free movement, throttle linkage for binding, etc.
Anybody else been there? Insight would be greatly appreciated.
Mark

jly535

Mine does that also, not always but more and more lately, I think its because of temp change here in the NW and WUR is thinking its cold out and going into warmup mode.

WERK-I

A lot of times this may be a symptom of the Aux. Air Regulator not fully closing. Many people with 930's are setting their AFR's on the rich side. If the AAR does not fully close, the additional air is allowing the engine to rev higher at idle.
Another problem I found on my car was on the throttle linkage pedestal. One of the springs had broken and prevented the throttle body from returning to its stop.

nathanUK '81 930 G50

Yep, sounds like the AAR. I call it CIS's electric idle valve as that is basically what it is for us. It's AKA the sliding disc / half moon thingy

jly535

My AAV is removed and still does it occasionallly, maybe I need to tighten hose clamps blocking off AAV hoses, I also think my WUR is in need of some tuning, most likely coming out this winter to send off to Brian Leask. Hey Full Quack, we should get a little gathering together for a day drive to Leavenworth in the next couple of weeks befor weather gets too nasty, I am in Everett, there are quite a few NWers on this forum. Jamie

nathanUK '81 930 G50

Sounds like your AAR is playing up aswell then.

fullquack

Hello there jly535,
So how do you go about removing/blocking off the AAR? I tried last year by just blocking off both ports, 1 on intercooler & 1 on manifold, and the car would not even idle! I obviously missed or overlooked something or needed to adjust something to compensate. Please clue in the cluless!
A day trip sounds cool, however, I'm chained to my ancient old house for the next 4+ weekends doing needed projects before winter sets in. I'm even taking some time off work to get it all done.
Leavenworth?....there needs to be plenty of places for **** stops....my non-stock suspension beats my bladder into submission about every 30 miles or so. My only complaint about modifing it.
Mark

nathanUK '81 930 G50

He blocked off the AAV. To be honest I always forget which is which, I prefer to say electric idle valve or vacuum limiter.

Mark Houghton

Sounds like your AAV was most likelly stuck in the partially open position all along, letting in some air, and all other tuning was done around this phantom air "addition". As soon as you plugged everything, now the mixture was way off and the thing would not idle. Just do an adjustment on your idle screw (the one that's inaccessible to all except those with skinny long arms), and it may solve the idle problem.
I live maybe 80 miles from Leavenworth. If you and/or jly535 should ever happen over this way, perhaps we could all converge on that little American Bavarian village and race up and down Stevens Pass. And I know of one other from your neck of the "west side"...Dr. Dave...that would probably also enjoy tooling over in his 930.

jly535

Mark we or I will definately let you know if we head that way, I usually like to take a trip to Leavenworth in October to russle up the falling leaves.

Full Quack, I have a 77 so no intercooler, but all I did was unplug electrical connection to AAV, removed both big hoses and connected them back together with a piec of solid rod about 3/4 diameter between the two with hose clamps, then I just use my center cable pull throttle to warm up with. I have a car lift if you would like to come over and tinker with your 930, or I would be more than happy to come over to your place and help if you got the tools. I am in the same boat, trying to get house back together for winter, it never ends. Jamie 425-422-5039 or jly535@comcast.net

fullquack

I've got the tools, I've got the 900 sq. ft. garage & I'm a real good wrench, just new to the 930 game. So I'll tinker a bit before I grovel for more help. Thank you all for the feed back and offers.
I'll keep the road trip in the back of my mind....but the 110 year old house is definitely calling the shots right now.
Thank you all again.
Mark

fullquack

Ok, I went home tonight & removed the AAR, adjusted the idle until it ran at 1000rpm. Did a road test, got back to the garage, & idle was low. Re-adjusted for 1000rpm, road test again. Stopped 4 times to test idle, 3 times idle remained at 1000rpm, 1 time it dropped to 1000rpm then climbed again back to 1200rpm. Got back to the garage, ran engine up to 2000-2500rpm then let it drop to idle, did that 1/2 dozen times, each time idle rpm was slightly different from 900-1100. Also has slight popping thru exhaust while at idle, Lean mixture??
Got frustrated & put AAR back on & re-adjusted idle to 1000rpm. Now the car idles just fine....arrrrghhh!!! The AAR's ohm reading shows 24ohms, should be 33ohms. However the small disk valve inside moves freely and snaps closed with it's spring pressure easily. Yeilding a gap of only 2mm(.080). OK? Or should it close off completely?
I'm leaning toward old & tired WUR that is not reliably controling pressure. What do you guys think?
My car has NO oxygen sensor so I have no way of checking AFR's. Can the AFR's be checked without dyno time? If I get the WUR rebuilt by Brian (which will then be adjustable) do I need a dyno to get it properly adjusted?
I think I'm begining to ramble...I had better stop now.
Mark

jly535

Full Quack Mark, I know what you mean, I think they are all just a little moody, mine seems to run a litttle different everyday, but runs good. My idle is at 1200 on cold startup then drops to 950 after warm, and occasionally searches for idle rpm, up and down, up and down. If I pull my center throttle adjust lever slightly up it smoothes out, so I think both of us are suffering from warn out WUR. I am definately going with the Brian Leask WUR, I think the UTCIS one is a little to complicated for my basically stock setup, or I prefer mechanical over electronic I guess. Anywho, if you have a freeday and the sun is out just post a message to go play, definately next spring we should get a little gathering out a few times. Jamie

nathanUK '81 930 G50

Mark, if you give BL your full details of your car he will be able to set it up ready for you. All that will remain is for you to possibly adjust your idle CO and your idle speed.

What's been modded on your engine?

Mark Houghton

These cars have driven me to drink excessively on more than one occasion. Don't worry about the rambling - it's a symptom of all 930 owners.

Let's see...you took off the AAV to isolate that as the cause of your high idle (and of course, plugged the air lines from the intercooler and to the manifold). Still, the idle is inconsistent. Your description of the AAV makes me think it's working just fine (have you been able to view the inner disc when stone cold to see that it's wide open, and when hot to see that it's closed). And it's normal to have a small gap in the disc when fully warmed up.

At a minimum you need to have someone test your idle CO to make sure you're at least in the ballpark before you continue chasing ghosts. Without the O2 sensor, you should be able to dial it in from lean to rich. I've got mine set close to 3.0% CO...quite rich by most standards but where I want to run it for peace of mind until I can have Brian L. do his magic on my WUR.