Rough Idle mk3 golf 2.0 8v ady

[Hodgey GTI]

As title says my golf has been running a little rough ever since I've owned it not exactly a problem but I'd rather it run smooth. Any help is appreciated.

https://youtu.be/pJD3u2XvafU

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[feenix74]

I am not a mechanic, but having owned a Mk3 for 20 years, a couple of things to try:

- what fuel are you using? VWs drink premium unleaded (use the 95 RON as a minimum 98 RON is better if you can afford it, go with the reputable service stations, I find I get much better fuel economy from the Caltex Vortex premium 95 RON than the Shell stuff or the United stuff)
- check the spark plugs and spark plug leads (if you are not getting a good spark in one or more cylinders then it will idle rough)
- check you do not have a leak from the exhaust gas return pipe (On top of the silver rocker cover of the engine, there is a square black box on the left hand side, there is a two-pronged rubber pipe that leads in and out of it, check that rubber for cracks, unfortunately Mk3 have a lot of plastic/rubber pipework around engine and if you have a crack it will bleed air which may cause it to idle roughly)

[Hodgey GTI]

Checked my plugs recently and they were fine, distributor looked good too, will check exhaust leak, I run e10, I'll swap to 98 from now on.

Thanks for the reply,

Rohan.

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[hahne]

ECU relay (30?) goes bad somtimes and gives rough idle.

[KKK VR6]

I run e10, I'll swap to 98 from now on.

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I don't think there's a single enthusiast on this forum who runs that shiit.
U should just stick with what it says on the inside of the fuel flap!

[Hodgey GTI]

I don't think there's a single enthusiast on this forum who runs that shiit.
U should just stick with what it says on the inside of the fuel flap!

When you say ****, you mean e10?


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[browntown42]

Switch to 95 or 98, My 2.0 pinged BAD when I ran 91 for the first few weeks of ownership until I read the fuel filler cap. 95 or Above.

[Hodgey GTI]

My filler cap says 91

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[feenix74]

I understand that E10 has a RON of 94. All the Government advertising say that vehicles of Mk3 age can use E10 but that you should check with your manufacturer. However, I have never found anything official from VW which says the Mk3 can use E10. I believe that E10 will give you worse fuel economy too. 98 RON did not seem to make any significant difference to performance or fuel economy over 95 RON for me. I have run a tank of regular unleaded in my Mk3 in an emergency situation but it is definitely rough.

[Hodgey GTI]

Just an update on my idle, I replaced my timing belt and it improved the idle a little bit but it's not perfect, when it's cold it sits at 1k dead till its warm and then goes back to bumping around 850-900. Going to try 95 fuel as my tank is near empty now.

Thanks in advance,

Rohan.

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