Mrmerlin

can you shut off the idle control circuit via the test port? test this cold and hot

byrdman454

Stan,
What should the car do when I jump the two pins? Should idle increase?
If it doesn't make a change, what is the cause? The ICV is less than a year old. It has had high idle with the old ICV as well.

Thanks

95carrera

That's frustrating. I have had my share of idle issues. Mine were caused by failed fuel damper and then by idle control valve.

Mrmerlin

what will happen if the computer is bad is that nothing will change .

IE when the pins are jumped the idle will not do anything and the screw will not make much of a difference when its turned.

this indicates a burned out transistor or diode in the computer due to a failed ICV being kept in service.

THE Icv in your car has a habit of wearing holes into the armature the brushes continue pressing into this and then eventually they capture the armature and it wont turn.

The computer sees this and tries to add more power to the torquer signal eventually this burns out components on your computer.

byrdman454

I swapped the computers with Crumper's 86.5 a month or so ago and the idle was still high.

Mrmerlin

how did your computer respond to the jumping the test port? ,
did you try jumping the test port in the other car with your computer?

SMTCapeCod

Anything new on this?

byrdman454

I finally got around to working this again. I did another smoke test (warm engine this time) and didn't find any leakers. On a guess, I swapped the new ICV with an old used one from my parts bin and this fixed the problem. The used ICV from my parts bin was a Bosch. The one causing the issues was a Lowe brand bought back in Feb 2017. At the time I believe Roger told me the Bosch was NLA and the only option was Lowe. I am not sure if the parts availability has gotten any better or not. I guess the lesson here is that don't assume new parts aren't the cause for issues.

ROG100

Glad you found the problem. Can you test the Lowe ISV to see if the valve is opening, sticking or? First problem with a Lowe unit.
Most of the time I do not see the need to change out the ISV - just needs cleaning if it is the original Bosch unit.
Not much of a choice when it comes to S3 ISV's.

Crumpler

Good work Mike!
Good detective work.

About time you did something productive

byrdman454

This old Bosch unit I put on is also not working 100%. When the engine is cold, the car starts up and immediately dies. This is the ICV failures I am use to seeing. I will just have my nephew add a little throttle at startup. Once it stays running, it is good to go. This was the reason I removed it to begin with.

The Lowe unit would start good, but that's about it. When cold, it would idle about right but once the operating temp got above the 1/2 mark the idle would start increasing all on it's own. When it was really hot during the Summer, I saw it idling around 1200. One more odd thing that it did was that when you blipped the throttle, the rpm would hang and take forever to come down. You could hear the hissing coming from the ICV then this happened. I know this was an automatic, but it was way slower than that. The old Bosch blipped the way it is supposed to.

There are three pins on this ICV. Roger, which pins do you want me to jump? Do you want me to send this back for analysis? It is less than a year old. Any chance they have a warranty on this?

byrdman454

Thanks for all the kind words Dave....LOL.

byrdman454

Well, the ICV warranty replacement (Lowe brand) I installed from Roger back in January has just failed again. This car is a daily driver so it gets a ton more use than most. The car had a very high idle at full temps, but the car would idle properly at lower temps. I installed my old Bosch one from the parts bin again and the car runs properly except at cold startup. You have to add throttle to keep it going during initial start but after that it is flawless.

I guess I will start looking for a NOS Bosch replacement off eBay. I might find one someday. It might take a while since these are NLA. Like Roger mentioned above, there are very limited choices now for the S3.

davek9

This one will work, been running one on my Twin Screw and just ordered another for similar cold start no hold idle issue as you described here.
My cars are not DD's so can't comment on how long they will last, but better than a worn out one that can damage LH.

Dave K

Crumpler