Finally changed the blue sensor....

[maxp]

If not the ISV, look at the idle switch. Had a similiar problem on a Passat years ago, the contacts tend to wear away.

Yeah worth eliminating.
Get a multimeter out, no need to switch the car on.
Connect to each pin.
Without touching the throttle at all you should have a closed ciruit (or 0 resitance)
Open it till you hear the first 'click' (at about 5% open), you should have infinite resitance (or an open circuit if you will)
Keep opening it all the way til you hear the next 'click' (at probably 95% open), and you shoul have a closed circuit again.

[Alec]

When I am lookin at the engine the idle switch is just on the throttle body isnt it, to the left? The contacts are always far apart.... dont know anything at all about the idle switch lol

The revs dont jump up suddenly when I touch the loud pedal and they dont dip dramatically after each rev, it also runs fine when warm (thats why I changed the blue sensor cus I thought it might of been temperature related).

I should be looking towards isv and idle switch?

[rubjonny]

sounds liek ign timing is out, had the same on mine. can also be caused by a leak in the zaust system. have you set it up as per the digi faq

[Alec]

It used to be fine though mate, would the timing go out gradually over time? I'll have a look at this ere digi faq.... if I can find it 

[DarnPB]

The timing being electronic can change with the changing of components associated with it. I change my ECU in an 8v and the timing was way out as a result. The old ECU was knackered but it still ran. The ECU takes information from various sensors around the engine, processes them and spits out a result by altering the timing and mixture settings. If the ECU gets given crap information to work on by recieving info that is inacurrate, then it will deliver crap. So if your blue sensor is a new one, and known to be good, then the engine may need to be set up again as it was probably set up to match a bad sensor. So start with the ignition timing, then go for the mixture settings and it should all become good.

[jezza16v]

When I am lookin at the engine the idle switch is just on the throttle body isnt it, to the left? The contacts are always far apart.... dont know anything at all about the idle switch lol

The switch you can see on the top of the throttle body is the 'full throttle switch', the idle switch is below the throttle body, you can't see it and its awkward to get to. You should be able to hear it click just as the throttle comes to fully closed. Mind you, the click does not mean its working or that the wires to it aren't broken.........

[Alec]

Jeeeeez this is gonna cause me some headaches I reckon lol. Cheers for the info guys, think I found rubjonnys guide, it the one with the "secret MFA mode" ?

Some of it still sounds a bit jargon but I will read it over a few times and consult the trusty haynes manual as a reference. I dont have a timing gun or emissions machine thingamebob but I can at least get it booked in to have the timing set up at my local vw specialist.
Not got a great deal of confidence these days when it comes to cars due to some health problems (at 23   )

Thanks again

[DarnPB]

Take the car to a Bosch agent and they will do a good job. Should only take them an hour. May be a good idea to take a printout of Rubjonnys set up guide and say, 'do it to that please!'

[Alec]

Bosch agent? Just called my local vw specialist who quoted about 50 quid.

The sensor I took out of it doesnt have vw/audi stamped on it, just says VDO and 12V with a part number that partially matched the official VW one I installed. Is VDO a oem manufacturer for the old golf bits?

[rubjonny]

this one:
http://www.golfgtiforum.co.uk/index.php?topic=33253.0

and yeah, VDO is an oem manufacturer