Help with CIS control pressures

Scott R · Scott R's Garage

OK, I still have a bad idle problem on my 80 SC, She starts up fine when cold, then the idle creeps up as time goes on, if it's just istting it only moves a little if I give it some throttle it starts to go up.

After a while It's hit about 2000 RPM and to get it down to 1100 you have to adjust the idle control screw all of the way clockwise.

If you shut it down it can not be restarted without advancing the idle control screw a few turns. Today I took control pressure readings and here they are: (and and I also removed the CSV and cleaned him up as well, and I can confirm that he does not appear to be leaking.)

Cold Control pressure: 58 PSI
Unpluged WUR first start, motor running: 36~38 PSI (fluctulates)
Plugged in WUR pressure rises quickly to 55-57 and holds
After 30min 22 PSI still in system
Started again pressure is low around 35 PSI

Visual inspection of the AAR shows that after engine is warm and running it is 100% closed.

Thoughts?

Scott R · Scott R's Garage

Oh forgot to add that I just checked the CO as well and it's ok. However after I stop the engine warm, then try and retstart it, it of course as I mentioned above idles low if at all, and the hydrocarbons are very low as well.

Scott R · Scott R's Garage

Bump for help,

Hampton · Hampton's Garage

Another bump - I'm having a similar problem with my 82 SC.

cmonref · 10-10-2005, 07:44 AM

Sounds like an aux air regulator problem. It is on the right side between the intake runners. Pull the electrical plug -- it should have 12v on it when the engine is running.

If it has the cirrect voltage, then it may be suffering internally. Run a search for AAR and you should come up with some good information.

Hladun · 10-10-2005, 08:04 AM

In your second post what you're saying is that you're not getting enough fuel. Have you run some injector cleaner recently? Is your fuel filter OK or did you get some dirty gas?

If you're doing it right, you're cold control pressure is high. "Plugged in WUR pressure drops quickly " from what?

When did this start? Did you do something that started it?

SC-targa · 10-10-2005, 08:30 AM

I've suffered the same problem on my 82. On my car, it's much worse on hot days.

See what happens if you unplug the O2 sensor. That helped, but did not cure mine. I'm thinking that I may have a vacuum leak under the airbox that is temperature sensitive. Like you I checked the AAR and all the other devices plumbed into the system. I actually disconencted them and plugged the ports, to no avail.

Good Luck,

Jerry Kroeger

Scott R · Scott R's Garage

Quote:

Originally posted by Hladun
In your second post what you're saying is that you're not getting enough fuel. Have you run some injector cleaner recently? Is your fuel filter OK or did you get some dirty gas?

If you're doing it right, you're cold control pressure is high. "Plugged in WUR pressure drops quickly " from what?

When did this start? Did you do something that started it?

That's a mistake on my part, I meant that once the WUR is plugged in the pressure climbs to 55-57.

And no on the injector cleaner, in fact I am leaning towards injectors now as it looks like I am bleeding pressure out the injectors after the system is shut down.

I keep 19 PSI in front of the fuel distributor, but I appear to have an injector or two that never closes.

And this has happened since I removed the CIS system during my engine drop, The car is very drivable, it just does not like to start when it's been running and then shut down for a 10 or so min. And of course the idle is all over the place.

I did replace the WUR this weekend with another that I have, and it did not really change anything.

Hladun · 10-10-2005, 08:53 AM

What you've said now about removing the CIS would have me suspect a vacuum leak.

Scott R · Scott R's Garage

Quote:

Originally posted by Hladun
What you've said now about removing the CIS would have me suspect a vacuum leak.

If there is then it's not in the usual places. I replaced all of the intake boots, and all of the injector seals while it was out, new o-ring for the throttle valve as well. Air boot is good, and I can open the oil fill cap and get the expected drop in RPM's. And if I simulate a vacuum leak, like pulling a line going to the distributor I get a CO change.

It would have to be a crack in the air box in a place that I can't see, or something like that.

byrd101 · 10-10-2005, 10:03 AM

Have you checked the decel valve. If it's bad it would cause a vacuum leak and a slow increase in idle. I had that problem a few years ago. It's easy to troubleshoot, just pull and plug the vacuum line. I was able to run without it for a week or so.

Scott R · Scott R's Garage

I have unplugged it in the past and noticed that it did nothing, I will try and run without it, thanks for the suggestion!

Hampton · Hampton's Garage

Everyone - Thanks for the info.

The electrical plug on the Aux Air Regulator had come loose. I reconnected the plug and the idle is back to normal. Thanks again!

Scott R · Scott R's Garage

Quote:

Originally posted by Hampton
Everyone - Thanks for the info.

The electrical plug on the Aux Air Regulator had come loose. I reconnected the plug and the idle is back to normal. Thanks again!

Oh man I hate you.

Three local mechanics and no one can figure my issue out.

vash · vash's Garage

scott, you need to test cold control press with the wur wire disconnected.

then reconnect and get warm press, car runing.

is that micro switch on the throttle working properly?

Scott R · Scott R's Garage

Quote:

Originally posted by vash
scott, you need to test cold control press with the wur wire disconnected.

then reconnect and get warm press, car runing.

is that micro switch on the throttle working properly?

I just removed the throttle housing and adjusted the throttle switch with an OHM meter. And the cold control pressure is 34PSI.