mk3 golf idle issues

[MOD500]

My Golf recently passed the MOT by the skin of it's teeth.

Mk3 golf 1.8 Auto ABS engine 1994

 

It took a very long time for the revs to settle enough for it to pass fast idle, It took long enough that they nearly gave up on it! Last year it had the same issue. It doesn't owe me much, but a few years ago I went to the effort of replacing the brake lines and the rear suspension bushes, an dealing with some rusty spots so body wise and mechanically it's got a few years left in it without major works, but the emissions will kill it off I don't get it sorted.

 

 

I've stuck VCDS lite on it, but there's not much feedback on the 1.8 ABS  engine.

It tells you there is a crank position sensor error. All ABS engines get this fault because there is no sensor present!

It will tell me if there is an issue with the Lambda sensor, but currently there is no lamda sensor error code.

 

I thought it was worth explaining that point because the first recommendation is to use a code reader, but that is telling me nothing!

 

It is often, but not always, sluggish during acceleration up until 3000rpm when compared to the other golf. During sluggish acceleration there is a drone/resonance seemingly from the exhaust, but I can't confirm as I can't replicate it on the drive because it only happens under load. There is an exhaust blow at the manifold to downpipe junction which I am reluctant to repair as it means buying many exhaust parts. This has been present for 4 years and started before the MOT issue.

 

 

Here is the list of things I think I need to go through:

• MAF sensor
• MAF Sensor wiring
• Throttle body loose   (checked this the other day.)
• Dead CAT
• Coolant sensor

Can anyone think of anything else worth checking?

Experience of similar issues would be a good help.

Is there any low cost way of checking the emissions without taking it to the garage?

 

I have the 'luxury' of owning 2 x mk3 golf's with ABS so I can swap. This will be handy with the CAT and MAF sensor + wiring.

 

Cheers for reading.

 

[purplebargeken]

Change the temp sensor and throw lots of carb cleaner in the appropriate holes. It's a start!

[drewd]

As above, coolant sensors are a common fault on these.

 

I had this engine in a Vento years ago and it pulled really well for what it was. Have you checked the rubber base block that the throttle body attaches to on the inlet manifold for splits? This was another common problem. Try wiggling the throttle body with the engine running to see if the idle speed changes.

 

Failing that don't these have knock sensors on the front of the block? If so check the insulation for the sensor. Ive never experienced this but have heard tales from others. Not sure how true they are.

[MOD500]

I'll order a temp sensor tonight and update once fitted.

 

The temperature seems similar to the other golf so I'm not sure, but it is the easiest part to change so it makes sense to start there.

 

I meant to do that last night, but I've recently been playing Red Dead Redemption 2 which seems to act as a black hole for many hours of my spare time.

 

 

Throttle body gasket is good. I've had that before!

 

Not sure about the knock sensor. I'll have a look into that.

[twosmoke300]

Throttle body rubber base mounting - pound to a pinch of shit