Deleting ISC

[Boostinsideways]

So I have no ac, no powersteering. What would I risk if anything by just deleting my ISC?

Edit:

In case you want to know why I wish to delete it, I am suffering from idle surge and have traced the cause to the ISC. These things are rather expernsive new. I can make a block off for like 5$

 

[Calan]

A better question is what would you gain?

 

[Boostinsideways]

Well I think we all know what a bad ISC causes.

 

[habitatguy187]

How cold does it get where you live? Without the isc you'll have funny symptoms on cold startup in cold weather.

 

[red92tsi]

Even in mid 70 degree weather I sometimes have to keep my foot on the gas for a few seconds to keep my car running when I first start it. I have no isc.

 

[jahjahSQC]

if it'll only cost you like 5 bucks as you say, then go ahead and delete it and report back with what happens.

 

[nuclearr]

I deleted mine for a short while I am currently putting it back on. My car will stall out untill it gets up to operating temp when I drive it. And that is in 90* weather. But I still have power steering and a/c. It will stall a/c off and no p/s input. I accutally get idle surge at trafic lights now.

 

[BK85]

Have you tried just pulling it off and flushing it with carb cleaner or at least WD40?

I had everything from stalling to erratic idle and after the flush it was much better and eventually it settled down completely.

I know my motor is a 420a but the ICS and ICM do about the same thing.

BK85

 

[gusu]

ECM-Link V3 supports ISC simulation.

It's also very easy to enable, I've only seen pictures of the interface and never used but I could still easily find it and enable it.

 

[steve]

Well I think we all know what a bad ISC causes.

Many people think they know. They blame the ISC for all sorts of idle issues, block off the ISC and FIAV and then think they know why they solved their problem. It's far more likely that their FIAV was stuck allowing too much air to bypass the throttle plate or that they had a leak somewhere else and by removing all the normal idle bypasses build into the TB get the idle flow rate back down to where they don't surge anymore.

Sometime the issue is the ISC. Notice that the tip is plastic and wears or gets coated in carbon, the TB ISC bore also gets dirty and both cause changes in how much air flows through the ISC bypass. The ISC coils fail and it gets stuck in some random position or a coil shorts and blows the ECU driver. They replace the ISC but never fix the ECU and then wonder why the system isn't working.

If you look at how much air is really flowing at idle and what the rate of RPM change is to small changed in airflow you'll see why it's so easy to have surging issues.


The ISC does three things; Assisting in starting, idle speed, emulate a dashpot to avoid stalling on throttle closure.

 

[93_tsi_fwd]

Better off just blocking your FIAV and retaining your isc. I have a good solid idle at start up. I'd look into getting a new fiav instead of block in tho. Grab a good isc from the junk yard or something, new ones are expensive. And yeah, like what steve said, check the ecu too if you fried the isc drivers.

 

[Boostinsideways]

I pulled my ecu apart, and it looks clean. No burn spots or leaking caps. I tested my isc with a multimeter and the numbers way outside of norm. With it unplugged the car idles fine. Have not driven it yet with the ISC unplugged.

I may take it for a drive once I get the exhaust back on Thanks for the help guys.

 

[LiquidX]

I'd listen to Steve before doing anything. If you know for a fact the ISC is bad, get one from Rockauto for around 70-80$. Works perfectly on my vehicle, it's just a stepper motor.

Me personally, I would not remove it. As mentioned earlier, I removed my FIAV and I have the occasional starting hiccup in colder weather. If you didn't check the FIAV innate an excellent writeup on how to by pass it for 100% free. I still don't know why people buy by pass plates..

 

[Boostinsideways]

Allright thanks Liquidx. I looked up the one on rockauto and its a lot better than coughing up the 134$ for an oem one.

 

[bertrenolds]

I'd listen to Steve before doing anything. If you know for a fact the ISC is bad, get one from Rockauto for around 70-80$. Works perfectly on my vehicle, it's just a stepper motor.

Me personally, I would not remove it. As mentioned earlier, I removed my FIAV and I have the occasional starting hiccup in colder weather. If you didn't check the FIAV innate an excellent writeup on how to by pass it for 100% free. I still don't know why people buy by pass plates..

I bought a FIAV blockoff plate so that I could keep my ISC but also make it permanent, it was easier then rigging something up. And autozone also has IACV's for $100 with a 2 year warranty so why remove it?

 

[Boostinsideways]

Because its 100$ to go towards something that will do absolutly nothing for me living in the south, never seeing a real winter, and not having any accessories.

 

[LiquidX]

I bought a FIAV blockoff plate so that I could keep my ISC but also make it permanent, it was easier then rigging something up.

The tech article I have posted goes over all of that information and is free to do the EXACT same thing the plates do. So explain what you were saying about making it "permanent".

http://www.dsmtuners.com/forums/articles-intake-exhaust/391977-free-fiav-block.html

 

[bertrenolds]

The tech article I have posted goes over all of that information and is free to do the EXACT same thing the plates do. So explain what you were saying about making it "permanent".

http://www.dsmtuners.com/forums/articles-intake-exhaust/391977-free-fiav-block.html

If I had a 90tb, which I don't then yea your tutorial is nice. Otherwise all I've seen are pop can mods or putting RTV in the passages and for $20 for a fiav block off plate it was an easy choice. And apparently everyone lives in the south, it still gets cold enough during the winter down there for it to cause problems. Why not spend $100 and save yourself the headaches? Oh wait, I enjoy having my car idle like shit for 5min when I'm trying to go to work in the morning?

 

[91stocker]

Well you shouldnt mod your dd in the first place. I dont care how my car idles before it warms up because its a toy that will never see rain or snow or cold weather. But i bought the block off plate because whats $20 and it fits and looks really nice, specially with the ss allen bolts.

That is an excellent write up though.

Side note, the fiav block off made a bigger difference in temp off my IM then the magnus heat barrier gasket did. Definitely a worthy mod.

 

[steve]

If I had a 90tb, which I don't then yea your tutorial is nice.

I don't know, it sure looked to me like me has information for both the 90 and 91+ style throttle bodies listed, you just have to watch for when the year specific examples are interspersed in the article.

Because its 100$ to go towards something that will do absolutly nothing for me living in the south, never seeing a real winter, and not having any accessories.

All three functions I listed are useful everywhere. It sounds like the only thing you really don't need is the FIAV for fast cold idle. But if starting assist, idle management, and anti-stall aren't worth $80 to you that's your choice.

 

[91mits]

excellent write up by steve, i too have weird idle surges, but looks like i might have a vacuum leak near the throttle body, sic tested out normal.