GTI 16v Cold idle problem.. Testing the ISV and wiring.. HELP!

[JRW91]

Hi, i'm new to this forum, have read a lot on here but just never posted..

I've just recently bought a 1997 Mk3 GTI 16v with an ABF engine.

The car will not idle when the engine is cold, it just ticks over and then stalls. It will start with a bit of throttle and will drive off as long as you keep a bit of throttle on. Once it is warmed up (couple of laps around the block) it idles perfectly, and will start normally and go straight to a perfect idle.

So far i have cleaned the throttle body, given the car a full service (new spark plugs, oil change, oil filter, fuel filter)
I have scanned the car using the u281 scanner, nothing showing up on there.
I have checked all the vacuum lines. All seem to be okay.

I have taken the ISV of, given that a good clean. Although i think that this is where the problem lies..
There is no 'buzz' or 'hum' from the ISV.. nor does it vibrate. Could anyone give me some helpful tips on how to test to see if this is the faulty part? i.e how to give it direct current to see if opens/shuts?

I have a multimeter.. but don't really know how to use it     Could somebody give an idea of how to test that power is running to the ISV and that it is getting the correct signals? Something to do with ohms resistance? Just not sure what i am looking for. As there may be a problem with the wiring harness/loom? I have given a visual check  but cant see anything that looks suspicious.

If there is anyone nearby who would be willing to give me a hand that would be very helpful! There will be beer tokens involved

Any help would be massively appreciated as its starting to drive me up the wall! Been working on it for a good week..

Thanks!
Jamie

[itavaltalainen]

get someone with vcds to run an actuator test - this will keep opening and closing the ISV (you should hear that if you listen with your ear next to it). If it does not make a sound put your voltmeter to voltage (20V range) and measure if a voltage comes there when the actuator test is running. If not you're probably looking at broken wire (they are white and black).

If you get voltage there and it's not clicking then the valve is f**ked. you can try to clean in with brake cleaner, has helped a lot with ISV on my 2E when it had once acted up.

[JRW91]

Will i be able to run an actuator test using a cheap ebay cable such as..
http://www.ebay.co.uk/itm/FTDI-FT232RL-KKL409-1-OBD2-Cable-VAG409-Interface-VCDS-Lite-works-on-Vista-win7-/181050728196

and will this cable/software work with my car? As i understand VCDS lite has limited function?

Unless there is anyone in Southend/Essex who would be willing to run vcds for some beer tokens?

Cheers..

[itavaltalainen]

yes should work with that cable, but not sure if vcds lite without registration will allow you to run actuator tests...
will try on my g/f's laptop if she lets me ... i have bitten the dog and spent 99$ to register it.

worth it really and if you struggle then you have support (and if you get a newer VW you can always upgrade to full VCDS .... actually it's 1$ cheaper to first buy the lite s/w and then upgrade  )

[JRW91]

Would be great to know if VCDS lite will allow me to run the actuator test before i buy the cable as i dont have $100 to shell out on the full software.

Already bought the handheld scanner but this only allows me to read/erase trouble codes..  Should've bought this cable in hindsight 

[itavaltalainen]

VCDS lite will do the tests, just tried on my laptop (well that the function is available, as I only have a 1.8 AAM it won't allow me to test the N71 = ISV).... but only the registered version. The non-registered copy I ran in virtual PC mode came up with "Sorry! This function requires VCDS lite to be registred...."

However you can manually try the valve, have look which of the contacts goes to gnd (the black wire). put gnd to that one.... and then try 12v on the other (goes to the white wire), it should click (once) now and click again when you disconnect 12v again.
the valve does not have a readback - its just on or off that is why a faulty one is not in your fault code memory, it just does not know what state it is in .

[JRW91]

Could you explain how to manually test it in a bit more detail for me please, im really not very technically minded. Sorry..

Should i just run a wire from the negative side of the cars battery to where the black pin is on ISV, and a wire from the white contact on the ISV to the positive side of the cars battery?

Thanks for all your help..

[itavaltalainen]

take the isv out - as i would advise against running from battery (if the two wires straight from battery touch you can cause quite a spark)

use an old audio system power supply that is roughly 10-15V... connect negative to the terminal where the black on goes to (to find out which this is put multimeter in ohm - resistance mode and measure the connectors in the plug against gnd e.g. negative battery terminal - where it shows 0 or very low this is the gnd one - obviously do this with battery disconnected)

then connect + 12 to the second pin in the isv... click - if not try to soak the valve bit in brake cleaner... take a slim glass jar for example, pour brake cleaner in and stand the valve in there - so that the electrics are not submersed.

[JRW91]

Right.. I took the ISV out.. hooked it up like you said, connected it up to a 12v battery charger i have. It buzz's and vibrates
So i guess this means that my ISV is actually ok..

So the next point of failure must be in the cabling leading up to the ISV.. Any ideas where to start with this, how to go about fixing or replacing?

Thank you so much for your help!

[itavaltalainen]

stick your multimeter probes in the plug and set it to 20V DC meausrement. Then start the car and see if you have 12V there... might not show anything if it is a slow cheap one.... alternatively use an led test lamp (if you don't have one you can make one from simple components that will do the trick).