Help required diagnosing problem please

[FrankyEight 10]

Hi guys

 

I've got a '94 2.0 16v which has the following issue; once the car get's up to temperature, the idle rises from normal (750rpm ish) to 1000rpm and stays there until I 'reset' it by switching off engine and back on again. Even then, after a few minutes of driving it'll rise back up to 1000rpm. I've been told this might be the ISV (idle stabilisation valve?. If so, could someone advise how I remove this and clean it and refit (I'm clearly a novice!). Also, I've been reading that it may be the temperature switch or thermostat? I'm not sure of the difference, again some advice on what the difference is and how they can be replaced would be greatly appreciated.

 

Many thanks in advance!

[dr_mat 0]

IMHO it's much more likely this is a result of a sensor fault on the engine. Do you have accecss to a diagnostic code reader? VAG-COM or one of the older two-wire diags tools should be able to query the 2.0 16v engine iirc.

[FrankyEight 10]

IMHO it's much more likely this is a result of a sensor fault on the engine. Do you have accecss to a diagnostic code reader? VAG-COM or one of the older two-wire diags tools should be able to query the 2.0 16v engine iirc.

 

Thanks for your reply dr_mat — I don't have access to VAG-COm or the other diags tools... do general garages have this equipment or should I find a VW specialist who does? I'm in Surrey. Cheers!

[dr_mat 0]

Also some prehistory:

 

https://www.honestjohn.co.uk/forum/post/index.htm?t=27965

 

Generic reader should work but be aware it's an early four-pin connector not the later SCART socket type. You may as well just get your multimeter out and check the engine temperature sensors have the right resistance.

[FrankyEight 10]

Thanks — post is really interesting and sounds just like my issue — do you know where the temperature sensor for the engine management system is located exactly so I can check and replace if necessary? Thanks for your patience...

[dr_mat 0]

I believe they're usually on the thermostat housing, but that might just be the VR6 I'm thinking of!

[FrankyEight 10]

I believe they're usually on the thermostat housing, but that might just be the VR6 I'm thinking of!

 

Thanks. Regarding VAG-COM, I might buy a generic reader from eBay or somewhere. They all seem to be SCART. Do I need a 4-pin adapter for this or do I need a specific 4-pin Reader? Cheers again!

[FrankyEight 10]

Thanks. Regarding VAG-COM, I might buy a generic reader from eBay or somewhere. They all seem to be SCART. Do I need a 4-pin adapter for this or do I need a specific 4-pin Reader? Cheers again!

 

Think I've found an adapter!

[dr_mat 0]

Check the compatibility. Even the early VWs with the SCART-type connector didn't actually speak full OBD2 protocols so the reader needs to be aware of this. I've never attempted to get one for a 2.0 16v. You can still get the 4-pin adapters with USB connected dongles that will work with the old 3.11 version of VAG-COM (which is still free from what I recall).

[Dox 22]

Could be an air leak? Check all vacuum piping around the engine bay going too / from the manifold etc for splits etc allowing air to enter the engine when the throttle is closed

[seanl82 23]

https://www.ebay.co.uk/itm/Brand-New-Audi-VW-VAG-2x2-KKL-2-2-to-VAG-16-pin-Adaptor-Diagnostic-Cable-UK/264045314782?epid=1488272422&hash=item3d7a53c2de:g:MzYAAOxyuR5TbAmy:rk:1:pf:0

 

 

This is the adapter you need. I've used it with Rosstech VCDS and worked perfectly on a 93 year VR6.