Super low idle

[GooeyGus]

Hi everyone. I have a question that I hope you can help with.

First a bit of background: My 90 TSi awd has always had a bit of a low idle, but it's always been pretty consistent. It will usually idle around 650, maybe 700 RPM.

Yesterday out of nowhere the car started to idle REALLY low, like 400-500 RPM. This basically started out if the blue on a cold morning.

The strange part is that the car is actually pulling MORE vacuum now than it did when it idled at 650. It's almost like the idle controller isn't opening or something.

So when I got home I did the BISS adjustment procedure, only to find that the BISS was already as far unscrewed as it could be.

Any ideas? Is there a way to clean the idle speed controller or at least a way to see if it's bad? I always thought the idle would go HIGH if the idle controller broke, am I wrong

 

[LiquidX]

VFAQ Site - Visual Frequently Answered Questions has a listing of the test procedures to do. Here are the links directly to the page used on the site. DmTaLoN's Idle Speed Control Test/Fix Page! 1G BISS Adjustment

 

[Jimmer307]

First try to adjust the BISS screw and the http://www.dsmtuners.com/forums/art...-fix-your-idle-surge-problem.html#post1591829 follow this thread.

 

[GooeyGus]

Thanks for the ISC link! I'll check that when I go to lunch (I'm at work right now) and report back!

As a side note, for the last year or so I've heard a rapid loud clicking from the isc area when I turn the key on but have the engine off. Since this problem has started the noise has been gone, so that might mean something.

Do these things make noise normally?

Also, is there anyone currently manufacturing these or will I have to find a used one?

Well I tested the ISC and I'm showing an open circuit between pins 2 and 3. Looks like I'm on the market for a new ISC!

 

[CHItown90gst]

Also, is there anyone currently manufacturing these or will I have to find a used one?

You could probably find a used one that someone is selling, but, I would recommend replacing it with a brand new one. That way the problem your encountering won't happen again.

http://www.dsmisc.com Has the cheapest OEM ISC's I've seen around. These units are brand new. I've personally bought from them before.

Omar

 

[TYGRR]

Make sure when you replace your isc that you take it to have it regulated or your problems wont go away. I did the same thing a few months back and i thought that it was just a remove and replace but soon found out that the isc must be regulated/calibrated if you will. Hope this helps.

 

[doggo]

Make sure when you replace your isc that you take it to have it regulated or your problems wont go away. I did the same thing a few months back and i thought that it was just a remove and replace but soon found out that the isc must be regulated/calibrated if you will. Hope this helps.

Just need to zero (or center) the ISC pintle travel via the ECU ground pin, after the new ISC is installed. This centers the ISC, so that you can then make any adjustments to the BISS (base idle set screw) to get proper RPM at idle. This is basic DSM maintenance tuning, not magic that needs dealer intervention.

The purpose of grounding the ECU pin is it puts the ECU into a mode where it will NOT try to control the ISC, even though the ECU is controlling other motor vairables like timing etc. This allows the mechanic to adjust the idle without the ISC auto adjusting for every adjustment he makes. Then when the ECU is ungrounded, the ISC will be able to travel from center, in either direction as necessary in order to as much corrective action as required to handle when your AC comes on, or when you have a hot engine and stop at the next red light.

Hope this makes sense to everyone?

Regards,
Doggo