Misfire/ MIL help

[BliarOut]

Just trying to track a MIL prob on a 1.2 3 cyl Polo. Came up with misfire on cyl 3 so I replaced the coil pack, cleaned.the plugs (and swapped 2&3) then cleared the fault codes. She runs better but still pops it on occasionally for a misfire on the same cylinder.

Seems to run OK with one notable exception, if you let it idle for about 15 seconds the RPM drops and you have to restart it to clear it. As long as you keep it off idle it's fine.

Doesn't run too bad, if it wasn't for the MIL you wouldn't think there was anything wrong day to day...

What's the best way to diagnose without too much equipment?

I'm thinking its gotta be either an injector or a valve but I don't have a compression tester.

[marmitemania]

It could be a timing chain fault if you google it they have lots of problems, not a good engine. The chain goes slack and the timng goes out putting on the man light.

[Lastinclass]

I've seen issues with cam sensors on that engine and as said above timing chain issues.

[Vulgar LS2]

Take the coil pack off, then take the fuel rail out with the injrctors still on it and get someone to crank it over for a second. That should highlight which injector is leaky if at all.

[BliarOut]

Seems it's a bit of a dog of an engine, glad it's not mine

Anyone tried a simple in tank cleaner like bg44k?

I'm looking for the simple stuff first as it's not my car so I'll be working on it at the GF's.

Is the cam chain on an adjustable tensioner or does it stretch to the point of replacement?

[BliarOut]

Just to add, got an OBD reader, the only fault is misfire on cylinder 3, wouldn't a cam sensor trip the OBD?

[BFG TERRANO]

HT lead breaking down?

[BliarOut]

Coil packs sit directly on the plugs, no HT side...

[V8RX7]

If the problem is only at idle I'd suspect an injector - if they are easy to remove, swap one around.