# ISV Delete DIY



## thesumof41is5 (Aug 6, 2009)

This thread is an ISV (Idle Stabilizer Valve) delete DIY. It is meant to help digi's and the like around the world fix bouncy idle, ridiculously high cold idle, stuttering, and many other idle-related problems.
The Car:








I did this today to fix what had been suggested I fix : bouncy idle, from 2500rpm down to 400, almost stalling, and yesterdays problem: 4k idle at cold until warmed up. It made me so mad and I couldn't stand it, so, here we go.
First, you will need very little tools.
1.)10mm socket 
2.)5mm Allen Key
3.)Screwdriver, or like me, a pocket knife screwdriver.
4.)Stoppers or "screw protectors, or nipples for vacuum inlets.








The Caps i got were $.88 at home depot, they are obviously gray, and can be found in the screw section labeled as "screw protectors".








First, disconnect the ISV itself from the 2 prong connector (yellow and white), and set the connector securely aside.(hide it if you want).








Next, loosen the hose clamp that holds the outlet side of the ISV hose to the intake manifold, and tug forward.
















Then, disconnect the other inlet hose completely from the intake accordion boot.
















At this point, I would suggest removing the ISV and the two hoses completely and throw them in your boot, or wherever.
Then, cap off the vacuum connections with said caps, I have 1/2" caps, so a hose clamp was necessary to keep the intake one from falling off, but the intake boot worked just fine with the 1/2".
















Next, you can remove the ISV bracket altogether, with the 10mm socket and your 5mm allen key.
















Then, replace the nut on the intake manifold, but leave the allen nut off, or with your leftover ISV, again, whatever.
The last, and most important step, is to tune the throttle air screw for the correct idle speed.








What I like to do is turn the screw all the way out and check the O-ring inside it. 
If it is bad, replace it in one trip to get the caps from home depot or you auto parts store. 
After the put the screw back in the TB hole, swist it all the way in until you feel it stop, and back it out ~2 turns. Get in drivers seat, start engine, with foor hovering on gas. It may be hard to start in cold mornings and need some attending, but after 15 seconds you should be fine. With the motor started, go back and adjust the screw for acceptable idle. Mine is flatlined at 750, perfectly smooth and no bounce.
This all also cleans up your engine bay. 








Any questions email or PM me, otherwise, happy dubbing!










_Modified by thesumof41is5 at 10:46 AM 10-27-2009_


----------



## vr2jetta (Dec 16, 2007)

*Re: ISV Delete DIY (thesumof41is5)*

Most people say this cannot be done, but like you, I have done it and had no problems. Of course if you are running a/c I would not suggest doing this at all.


----------



## thesumof41is5 (Aug 6, 2009)

*Re: ISV Delete DIY (vr2jetta)*

That is exactly what I thought, and I have the compresso for A/c, but it doesnt wok or have hoses connected, ya, if your ac does work and is connected I suggest not doing this or at least leaving your idle higher.


----------



## Mr. Ninja (Mar 28, 2005)

*Re: ISV Delete DIY (thesumof41is5)*

why wouldn't you just fix the issues that are causing the runability problems?


----------



## thesumof41is5 (Aug 6, 2009)

*Re: ISV Delete DIY (Mr. Ninja)*

The ISV was the root of my problems, and since I didn't have access to a working ISV and I'm trying to strip the car down to barely anything, eventually shave the bay.. etc, I figured I would start now and prevent other issues and headaches and expenses down the road.


----------



## rabbitvw1984 (Jun 12, 2004)

*Re: ISV Delete DIY (thesumof41is5)*

for starters, well documented..http://****************.com/smile/emthup.gif 
i have the notorious bouncy ass idle on a 92 jetta i just bought, and i have been seeing some controversy over deleting or replacing the ISV..
this weekend i am going to go out and first clean the crap out of the ISV and record results at idle/load and driving condition. then i am going to remove it completely and cap the lines and record the same data. 
I will def let you guys know what i come back with... i guess we'll see....


----------



## thesumof41is5 (Aug 6, 2009)

*Re: ISV Delete DIY (rabbitvw1984)*

Good Idea, seeing as you live in NC weather changes aren't a problem, so a high start idle wouldnt be necessary. Up here in freakin coldville I have to set the warm idle to about 1200 to get it to idle on startup. But it makes taking off a lot easier http://****************.com/smile/emthup.gif


----------



## DuncanDonutz (Nov 17, 2009)

*Re: ISV Delete DIY (thesumof41is5)*

My ISV has been un-hooked since I bought my GTI back in September (still connected to vaccum system, but not plugged in.) The only symptom I have from this is it doesn't want to idle when it's really cold. Whenever I had plugged it in it makes the idle rev up to 3500. Glad I saw this DIY I will be completely removing my ISV now.


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: ISV Delete DIY (DuncanDonutz)*

Yeaahhh I just spray WD-40 into them, use jumper wires on the battery to the ISV to trigger it plenty of times to loosen everything up, flush with more WD-40, repeat until reacts quickly.


----------



## otakuphill (Aug 13, 2009)

*Re: ISV Delete DIY (thesumof41is5)*

Anyone do this on a 16v? What about the cold start?


----------



## sciroccosven (Sep 16, 2001)

*Re: ISV Delete DIY (otakuphill)*









Here is a good read.


----------



## JULIOVR6 (Sep 13, 2007)

*Re: ISV Delete DIY (otakuphill)*


_Quote, originally posted by *otakuphill* »_Anyone do this on a 16v? What about the cold start? 

X2 anyone
can i delete the ISV to my 93 passat 16V w/o having any problems?
TIA http://****************.com/smile/emthup.gif


----------



## g3mccotter (Mar 13, 2006)

*Re: ISV Delete DIY (JULIOVR6)*

im wondering if this is my problem, kinda weird but when my motor is cold it idles just about a grand and once i drive it idles up around 2 grand just above or just under.... it started doing this after i ported my intake mani and threw on the larger TB... i was wondering if the TB i put on maybe just had the screw set higher but that wouldnt make sense since it starts lower when cold. is it my ISV? or possibly another vacuum leak that is a lot more touchy now that i have more air flowing??? i dont know i hooked all the vac hoses back up that were originally in the TB.... i would just mess with my idle screw but its really hard to get to cause its in the back and doesnt give me a lot of room to adjust...


----------



## TheBurninator (Jan 7, 2009)

*Re: ISV Delete DIY (g3mccotter)*

you should use longer vacuum cap on the manifold side and use a plug on the intake boot instead of a vacuum cap if you are going to do this.


----------



## soontobe83 (Mar 31, 2009)

*Re: ISV Delete DIY (TheBurninator)*

great DIY.. took that advice and deleted both on my jetta and my GTI......


----------



## Brian.G (May 8, 2010)

Good write-up:thumbup::beer:

BG


----------



## MK2SnowPilot (Sep 8, 2005)

Great DIY!

But for future reference - Most of the "bouncy idle" problems are due to the idle speed switch being out of adjustment or the wire going to it (and the WOT switch) being broken. Without this input the ECU doesn't know that the car is idling so is constantly making adjustments based on O2 and CTS inputs as if you were driving around. When it sees the proper input it engages a default fuel map and doesn't constantly adjust things.

Nice easy diagnosis too - if the two-wire wire going to the TB checks out as OK (you have continuity going to both wires from the ECU plug) then press simply press the WOT switch and if the idle changes then the idle speed switch (found underneath the TB) is broken or out of alignment.

You can also use a jumper wire to jump the wires at the connector

You can see the WOT switch on top of the TB in the picture below. You'll have to look underneath the TB for the idle speed switch - just follow the wire on the back of the WOT switch pictured. Don't know why the owner would have a hose clamp on it though:


----------



## TheBurninator (Jan 7, 2009)

MK2SnowPilot said:


> But for future reference - Most of the "bouncy idle" problems are due to the idle speed switch being out of adjustment or the wire going to it (and the WOT switch) being broken. Without this input the ECU doesn't know that the car is idling so is constantly making adjustments based on O2 and CTS inputs as if you were driving around. When it sees the proper input it engages a default fuel map and doesn't constantly adjust things.


QFT

Yes it can be done, usually people pull them off for the wrong reason though.

The screw caps used in this DIY are the wrong ones to use on an engine. Use actual vacuum caps from the autoparts store. They even have ones that can be inserted into the intake boot to completely remove the 90* elbow.

The Bracket that holds the ISV is also there to support the intake manifold.

*Also, make sure you do NOT unplug the ISV with the car running.*



If you guys are having trouble with the ISV you may want to try cleaning it very well (use a sensor safe cleaner) and adjust the adjustment screw on the ISV until you cant blow through the ISV.



Gotta love Vortex Mechanics... remove a part that is still working when it wasn't the issue in the first place. :banghead:


----------



## thesumof41is5 (Aug 6, 2009)

Glad this worked for everybody that did it.. and i just recently re-installed mine for the winter but hate the up down up down idle . Idle and WOT switches are fine on mine, but those tiny tiny bolys that hold it to the TB snapped so i used the hose clamp i had at hand.

And I was doing this on the cheap, hence using the home depot caps. 
Didn't want to spend the $37 or some shiz people are askin on here for a new ISV.

Even the JY knows what it is and how much they are worth lol.

But ive gotten better jobs and made friends, and have about 20 bosch ones from hyundais, but i dont think any part #'s match. They all make it idle at 2000.


----------



## MK2SnowPilot (Sep 8, 2005)

thesumof41is5 said:


> Glad this worked for everybody that did it.. and i just recently re-installed mine for the winter but hate the up down up down idle . Idle and WOT switches are fine on mine, but those tiny tiny bolys that hold it to the TB snapped so i used the hose clamp i had at hand.
> 
> And I was doing this on the cheap, hence using the home depot caps.
> Didn't want to spend the $37 or some shiz people are askin on here for a new ISV.
> ...


You could probably MAKE one work with the right electrical knowledge but even a few $5 junkyard ones can help diagnose problems. With luck at least one will work half-decently.

Also - I wouldn't be surprised if you have a vacuum leak.

Commonly overlooked vacuum leaks on these motors:

Oil Dipstick tube (the plastic piece at the top)
Injector O-rings
Brake Booster
Idle speed screw o-ring


----------



## Seax_Smith (Jun 1, 2007)

I always cringe when I read threads like this. Every digi car I ever purchased had Volitile Idle Syndrom. a couple hours with some sensor safe cleaner, some diectrict grease, 220 grit, so conectors and some 14 gauge brown wire and a can of starter fluid always fixed it.

Go through the digi once as described in the bently (yes you have to jump back and forth between sections) and you rarely have to deal with it at all after that.

Replace the old vac lines with 3 mm blue silicon lines, and then spray everything that could be a potentail vac leak with strater fluid and listen for an RPM increase. Clean up the grounds and be sure they are all grounding. Be sure the grounds going to the head are actually going to the head. Check, clean and adjust each component, as necessary as oulined in bently.

Jump thorugh all the hoops in order while setting the timing.

To get rid of the dead spot off the line, get a chip.

There is a proceedure for adjusting the idle for a reason and also a reason you do it after setting the timing.... tweaking the idle screw without clearing the memory first and disabling the hot strat function is a bad paln and leads to other issues.

Is always amausing how much time and effort people will put into "out thinking" a lil ECU that has it's origins in the late 70's and looks like some kid's science fair project once you get it out of the box.


----------



## TheBurninator (Jan 7, 2009)

Seax_Smith said:


> Is always amausing how much time and effort people will put into "out thinking" a lil ECU that has it's origins in the late 70's and looks like some kid's science fair project once you get it out of the box.


You sir hit the nail right on the head. I especially like this part.

I don't know why people remove things like the isv to fix an issues when it more than likely isn't the issue.

And to OP the caps from home depot are sooo ghetto. 5 bucks for a pack of proper caps from any autparts store would be a much better choice.


----------



## dragbike14 (Apr 25, 2010)

gotta love trolls sneaky little buggers walking around the vortex forums breaking into threads and setting them on fire :banghead:


----------



## STEALTHCORRADO (Oct 14, 2005)

dragbike14 said:


> gotta love trolls sneaky little buggers walking around the vortex forums breaking into threads and setting them on fire :banghead:


X2 and a:beer: to you


----------



## vwcrackerjack (May 15, 2011)

All I got out of this is that I definitely need to get a bently. Haynes sucks. Even after years of reading them I'm still lost


----------



## Russix (Jul 10, 2009)

Anyone know the difference between a three pin ISV from a CIS-E system and a two-pin ISV from Digi I?
The two pin digi has space in the middle for an extra pin, are they interchangeable?


----------



## Glegor (Mar 31, 2008)

Russix said:


> Anyone know the difference between a three pin ISV from a CIS-E system and a two-pin ISV from Digi I?
> The two pin digi has space in the middle for an extra pin, are they interchangeable?


NO! they are not..

they are totally different..

i think digi1 and digi2 are interchangeable, but not CIS-e


----------



## theshanks (Sep 14, 2011)

To the O.P. Whats the brown wire grounding bolted to the manifold support? And why do you have the WOT trigger clamped so its always tripped? Somthing isn't right about that. In a healthy Digi when you get the revs up near 2000 and depress that you would notice it bogg down a bit untill you're into a high RPM situation. I suspect you have worse issues than the ISV.


----------



## Glegor (Mar 31, 2008)

theshanks said:


> To the O.P. Whats the brown wire grounding bolted to the manifold support? And why do you have the WOT trigger clamped so its always tripped? Somthing isn't right about that. In a healthy Digi when you get the revs up near 2000 and depress that you would notice it bogg down a bit untill you're into a high RPM situation. I suspect you have worse issues than the ISV.


switch is clamped on the bracket, not clamped closed making contact..


----------



## theshanks (Sep 14, 2011)

Glegor said:


> switch is clamped on the bracket, not clamped closed making contact..



My mistake, I was looking at the picture on a very small screen. Now that Im on a good sized one I can see how its clamped. But like Burminator also said, kinda silly to delete the ISV when you can just clean and adjust it.


----------

