VW Golf Mk2 Owners Club

Idle problems MK1

November 26, 2025, 10:57:11 PM

Greetings! I had gone through a couple shops to try to fix the unstable cold idle of my MK1 Golf Cabrio (1991), with the 1.8lt, 90HP engine.
It seemed the idle valve was the problem, I replaced it and the issue persists. A couple years ago, a technician who seemed to know a lot of the older VW Golf said he chose to leave it running well when hot and not that well while cold.
In fact, about 1:00/1:30m after starting the engine, and revving it smoothly, the Idle becomes stable and the car runs well.
Has anyone ever experienced the same issue? I believe this engine (injection) is already an MK2 gen.
Cheers, Pedro

Re: Idle problems MK1

Reply #1 – November 27, 2025, 06:56:14 AM

Hi Pedro,

Where abouts in the world are you from?
Reason I ask is that country dependant, VW put different engines into the golfs.
You mention that you have a 90hp injection engine.
In that period, in the UK, the only injection engines the mk2 had were the GTI engines, both over 100bhp.

However, there are a lot of similarities, for instance, the first thing I'd check would be the coolant temperature sensor.
This is (possibly) a blue sensor, usually mounted to a flange on the head where the top radiator hose is fixed.
Get the car running normally, then disconnect it, if the idle changes, it's working ok, if not, then there is a problem.

Re: Idle problems MK1

Reply #2 – November 27, 2025, 11:30:37 AM

Many thanks! I am in Portugal but the car was imported...i believe from Germany in 1996. I tried the sensor you mentioned but the problem persists
Any other ideas?
Tks in advance
Cheers, Pedro