Will my Mk2 Digi ever stop stalling??????

[Richie]

I need help and am getting desperate !!!!!!!!!!!!!!!!!!
My 8V Digi wont stop periodic stalling when she's cold. It has been driving me insane and have just had it checked out by the well renowned Bosch Electric specialist in South Somerset. I even printed rubjohnnys sticky "How to tune a Digi" and gave them that (many thanks). She received a new blue temp sender, dizzy to coil lead and a new rotor arm and has been checked on the Bosch diagnostic system.

Result?
Its super smooth and goes like the clappers also when cold!!!! but has stalled 3 times today!!!

Anybody got any ideas???  please I'm begging

[Uku]

check your idle control valve or what ever its called , the round unit on top of the rocker cover , if this is duff the car wont idle well when cold and will stall , clean it out first with carb cleaner (i soaked mine in wd40 over night lol) and check connections to it , it should be making a whining noise when the engines idleing. if not its not running due to one of the reasons i gave. a new ones v expensive so source one from a scrappy if it is dead.

[Uku]

theres another item i can think of that can cause rough running also , the knock sensor on the front of the block can corrode and no longer work , i had to replace mine a while back , make sure its done up to 20nm as well , no more no less as thats the torque it needs to be at to work right.

[rubjonny]

have you checked out the idle switch, and does the idle ever get a bit unsteady?

[Richie]

Hi Rubjonny, thanks for your help, I was hoping you would take a look at this

Sorry but what's the idle switch?  I've read a lot about the throttle cut out and broken wires wires under the throttle body. Do you mean this?

The idle is perfect @ 800 rpm, sometimes though when you drop the clutch they drop to about 600 then it splutters and then goes back up to 800 and stays there.
Uku recommended looking at the knock sensor, I've never heard this causing a problem before, have you heard of this? as the plastic shroud on mine is broken and the wires look a bit dodgy.
Some say clean the ISV with carb cleaner and some say (Steve Cresswell) its pointless.
Should I dig deep and replace the ISV with a new one??

Again, your help and knowledge is much appreciated..................

[rubjonny]

the idle switch is located underneath the throttle body, you should hear a 'click' whenever you close the throttle.  If that checks out, look closely at the wiring behind the throttle body, mine had a habbit of snapping every couple of month or so till I extended the wiring.  Make sure that with the throttle closed the switch plug passes current, it stops when the throttle is open half way, then starts passing current again when held wide open.  Then check the engine side of the connector for 5v when the ignition is on.

Check the static timing is right, and if you have a timing light check the ignition timing.  Then when the engine is above 80 degrees, pull the blue temp sensor & rev it over 3k 3 times and check the idle speed

[Richie]

Thanks for that,
I'll try this out when I get the chance or even let the Bosch garage have a look.

On another matter, I'm loosing water/ coolant alarmingly. The rad  and system have been pressure tested and no leaks found. Do you know of any well known common causes? One garage said it might be leaking from the plastic adapter on the right side of the head which then goes toward the heater bypass valves. sound familiar?

Cheers again

[rubjonny]

yup, common issue along with the other plastic flange on the front of the head.  Dirt cheap to buy from VW so get yourself down there asap