1.4 TSI BMY idle misfires

[danieltv]

MK5 Golf 1.4 TSI 140hp stutters and misfires on idle, but drives perfectly fine.
I have changed complete timing chain kit + cleaned the intake valves. What else could it be?

[Aranogar]

Have this same issue mate sounds like a random misfire at idle and splatter sound then when driving is smooth. I’m a mechanic and from what I can gather it is to do with the fuel system where at idle not enough fuel is being drawn causing a slight rough idle. I’m going to start by replacing in tank fuel pump and fuel filter and filling up with shell v power and adding some kind of fuel additive in the hope it will clear the pipes and injectors of any debris in the system.

Changing the timing chain was a solid move tho mate. Don’t leave car in gear whilst parked and engine off, mate of mine did so and the car rolled over night then when it came to starting it.... you can guess what happened


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[FLAPPERJACK76]

Spark plugs ?

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[Crasher]

Have you done a compression test? These are very prone to excessive exhaust valve guide wear.

[Crasher]

Don’t leave car in gear whilst parked and engine off, mate of mine did so and the car rolled over night then when it came to starting it.... you can guess what happened

It is crazy we have to give this advice, VW should not have designed the tensioner without a return spring like the EA888 engine. Friends of mine in the trade have had all makes of modern cars with chains jump even when changing the clutch, it isn't even just VAG who are stupid.

[danieltv]

Have this same issue mate sounds like a random misfire at idle and splatter sound then when driving is smooth. I’m a mechanic and from what I can gather it is to do with the fuel system where at idle not enough fuel is being drawn causing a slight rough idle. I’m going to start by replacing in tank fuel pump and fuel filter and filling up with shell v power and adding some kind of fuel additive in the hope it will clear the pipes and injectors of any debris in the system.

Changing the timing chain was a solid move tho mate. Don’t leave car in gear whilst parked and engine off, mate of mine did so and the car rolled over night then when it came to starting it.... you can guess what happened


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It has always driven on Shell V power, so it should be "clean". I have heard it could be the fuel pump for some reason... Stupid bloody engine.
The new timing chain has a different design from 2018 if you buy straight from VW and should last much longer

[danieltv]

Have you done a compression test? These are very prone to excessive exhaust valve guide wear.

Car only has 94.000 km. Spark plugs were changed at 79.000km original by VW so they should be ok.
Dunno where to look

[Crasher]

I have seen them blow the ring land out of a piston and burn out exhaust valves by 25K miles so 40K klicks, easy. Never assume, always check... twice. Which octane (RON) of fuel do you use?

https://live.staticflickr.com/65535/49459463546_6e6c041cee_o.jpg (https://flic.kr/p/2imyFnu)
https://flic.kr/p/2imyFnu

[danieltv]

I have seen them blow the ring land out of a piston and burn out exhaust valves by 25K miles so 40K klicks, easy. Never assume, always check... twice. Which octane (RON) of fuel do you use?

https://live.staticflickr.com/65535/49459463546_6e6c041cee_o.jpg (https://flic.kr/p/2imyFnu)
https://flic.kr/p/2imyFnu

I use Shell V Power for the last 3 years. It is 99/100 RON fuel.
Would it not use oil if it had piston problems or smoke like a train when I take the oil cap of?


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[Crasher]

This particular car only had a misfire which we traced to a low compression which we suspected was a burnt valve. With the head off we could see the bores were mirror glazed and would need a honing and when we took two of the pistons out, bits of the lands fell on the floor; there was no smoke, oil consumption or even damage to the bores. We ended up fitting a new engine but that's a LONG story.