Site Newbie - Pic of my GTI and and a couple of techie questions.........

[illumin]

Hi guys,

Had my GTI 2 weeks now, just need to iron out a few little problems.....It's a 1991 8v PB engine code. I have just had it tuned this week and the garage replaced a temp sensor which was apparently causing an erratic idle. I also replaced the dizzy cap, rotor arm and plugs this weekend. Problem is the erratic is still there, but now very occasional instead of all the time - any ideas on what it could be? By the way, is the metal "shield" around the dizzy cap a neccesity? Mine is rusty as hell and doesn't really fit the new dizzy cap.......

Also, when I accelerate then back off there is occasionally a slight missing/juddering feeling - any ideas what this could be? Any help/advice appreciated.............

[...joe]

sounds like your timing needs sorting, also ditch the sheild around the dizzy, not essential in any way! also check your ISV is working ok....

[illumin]

Thanks for the reply - it did have a new head last year, I think the guy that owned it did his own mechanical stuff so the timing could be out a bit. Sorry to be dense but what's the ISV?

[knobby]

Ok i think this is the right bit...

On the top of the rocker cover.. where the filler cam is.. the other side there is a plastic mushroom shaped bit that also goes into the top of the rocker cover.. This is your ISV, (idle Stablizing Valve) this has an air pipe connected to it.. They fill up with oil and crap.. Just take it off.. give it a good clean with some carb cleaner.. There is also a mesh under this on the top of the rocker cover.. u may have to remove the rocker cover to clean this mesh.. but its worth doing.. have a look at the following link.. its a great little site which just gives you a few pointers on getting things runnning right.. TAKE A LOOKY!! 

http://www.members.tripod.com/~fuelie/tuneup.htm

Hope this helps..

Knobby!

[Veedubgt18v]

also check all vacuum hoses and rubber pipes cos digifant (pb engines) are very sensitive to airleaks. especially check the pleated pipe after the maf (airbox sensor) and where the rocker cover conects to the isv curcuit.

[monzablue16v]

TAKE A LOOKY!!

http://www.members.tripod.com/~fuelie/tuneup.htm

The Italian tune up sounds lethal!!!!!

[knobby]

I really like the warning note....

Warning #1:
The following procedure can blow your engine to: smithereens, bits, pieces, orts, perdition and kingdom-come. If you own a high-mileage, low-compression, oil-swilling, rod-knocking, piece o' crap car (you know who you are, don't you), don't bother with the "Italian Tune Up" because you will end up walking home from what's left of your sorry pile of smoking and hissing ex-VW junk. OK? (I'm not kidding.)

  Superb!!!

Knobby!

[illumin]

Hi guys
Thanks for the tips and that webpage link was very informative. Don't think I will be trying the Italian tune up though! 

[...joe]

Ok i think this is the right bit...

On the top of the rocker cover.. where the filler cam is.. the other side there is a plastic mushroom shaped bit that also goes into the top of the rocker cover.. This is your ISV, (idle Stablizing Valve) this has an air pipe connected to it.. They fill up with oil and crap.. Just take it off.. give it a good clean with some carb cleaner.. There is also a mesh under this on the top of the rocker cover.. u may have to remove the rocker cover to clean this mesh.. but its worth doing.. have a look at the following link.. its a great little site which just gives you a few pointers on getting things runnning right.. TAKE A LOOKY!!

http://www.members.tripod.com/~fuelie/tuneup.htm

Hope this helps..

Knobby!

the ISV is an idle stabilisation valve, its a cylinder about an inch and a half in diameter, with a plug on one end and a hose going into your inlet on the other. when the ignition is on it should be'buzzing'. you can hear/feel it. they get clogged up and apparently the best way to clean them is to sit them in a bath of petrol and let it buzz to clean itself out.  knobby was talking about your crankcase breather, which if f**ked can also give a bad idle. check the bung that sits in the rocker cover below the crankcase breather(mushroon shape thing) for splits as thats quite common.