8valve idle /oil probs...

[gizago]

Just got an 8 valve  '90 5 door. Engine has an 8 valve head on a 2 litre passat bottom end(dont kno what engine code) , fast road cam and stainless exhaust, but standard airbox etc. Runs well and pulls strong, but sometimes it wont idle, and it hunts between about 500 and 1100 rpm. Is this likely to be a minor fault like a vacuum pipe or something more sinister?? Also, when coming off the gas after giving it a bootfull the oil light flickers on- the oil level is fine, and I'm using 10w40.

Ive read through here-

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

But dont know if the car is digifant or K-jet  (how do I tell??).

Cheers, Mat.

[Pluginz]

Hey up bud.

Your motor is sounding like a Digifant to me by the year (1990).  Digi is 87-88 onwards until about 1992.

The hunting could be a wiring fault.  Behind the throttle body there should be a wire with a connector, I think its the idle switch.  When I disconnected mine a few years back i used to get your symptoms, revs up and down.

Have a good look at the wire, check for breaks and stuff. Also check there is voltage.

Im not sure about your oil light flickering on, oil pressure?? Maybe there is a wiring fault with that aswell.  There are several wires with space connectors that go to the oil cooler, give them the once over too. 

[gizago]

Cheers bud, I want to have a good look through the wiring anyway as the car has had lots done to it over the years and I'd like to make sure its going to be reliable. Thanks for the tips.

[X4MGS]

Could be the idle valve or the blue temp sender if it's a digi...

[gizago]

Cheers mate, I'll check them out. Frustratingly its an intermittent fault so will be a a b!tch to track down 

[X4MGS]

Blue temp sender can be tested by running the car and then unplugging it on tickover and you should hear the engine start to run erratically...

Not sure on the Idle Valve.... Someone on here will know for sure!!

[dadrathers]

Classic sympton of the idle switch. It is easy to check if you have a multimeter although you can do it by ear. It should click just as the throtle hits the stop. Even easier cos you don't need the engine running. Not so easy to adjust as it is located under the throttle body and is all but invisible. If you need to adjust then take the air hose off.

If you do a search you will find loads of good info on exactly how to check.