Mongo

Is there any way to bypass the idle control valve completely without causing an erratic idle (to the point of stalling or exceeding 800 RPM)? This has been ongoing and I'm looking for a temporary fix besides WD40 to deal with the ICV. This thing is getting quite annoying and I know I need to do my intake service.

AO

Short answer is no.

Mongo

There is one thing I have thought of that may really clean it up and lube it better; and that is to saturate it in WD40 and then start the car with the bypass vacuum line at the T-junction disconnected. I would then manually plug these up by hand to force the computer to open the idle control valve, then take my fingers away from the vacuum lines to unplug them in order to send the signal to close it. Doing this a couple of times may break loose whatever is causing the computer to overcorrect the idle. I think I'll give that a try and post my findings that will later make it to the great Rennlist Search Archive.

Jim bailey - 928 International

There are at least two failure modes....one is dirty , the other is the brushes of the electric motor wear out. WD40 will not fix the brushes.

Mongo

Holy crap check this out! I did what said above in the parking lot at my work and the thing runs like a charm now! I mean the LH must have totally wigged out over plugging the lines and surging the idle like crazy to correct it, but it's working now!

Jim bailey - 928 International

Wally P cleaned his I S V several years ago with good success ...it can work and it is cheap and easy ALL GOOD THINGS !

Mongo

I'm sure they can be cleaned to the point where they work as good as new...if done properly with patience and time.

classic_cars

Is there an idle control valve on an '84?

mark kibort

cut the white wire in the ECU bundle cooresponding to the idle fuel cut off switch. it will idle higher, and could hunt more when really hot, but it would be no where near as anoying as the faulty idle stablization circuit. (put a switch on the wire so you can turn it on and off)
when racing, i disable it due to engine idle stability issues.

Mk

Jim bailey - 928 International

USA 1984 does not have an I S V ...

Mongo

I'm bumping this thread because it has once again started to act up.

Mark, how high is the idle if I cut this wire? Is it the white wire in the harness connecting to the LH ECU?

Mongo

Oh and if I cut this wire, will the increase in idle put stress on the automatic transmission/drivetrain?

Jim bailey - 928 International

Andy there comes a time when you just have to suck it up and FIX IT RIGHT. The car is begging for an intake R and R ! Start cutting wires in the harness and you become that infamous P O that people wish they could find and hang ...

Mongo

This car will never have another owner.

I also don't have a place where I can R&R an intake right now. I'm about 517 miles away from a place with the proper tools.


Believe me, if I had the ability, I would have done it by now. Purchasing my parts is not an issue.

marlinspike

Someone once e-mailed me a way to jerry rig a replacement for the idle control valve that works quite well. It involves some screws and a self-fabricated aluminum bracket. It was done on a Mercedes, but it's CIS so it's basically the same. I'll see if I can find it. Tell me your e-mail and I'll forward it to you.