Polo 6n2 cylinder 1 misfiring idle

[Nevalenko]

Hi all.

Earlier this his year I bought my first VW for my girlfriend, a '98 polo 6n1. Great car. I've come across a bit of a problem though. A few weeks ago I noticed it was running a bit rough. After inspection I've discovered it's missing on cylinder number 1. I've done a fair few tests, like checking the plug leads, all ok. Changed plugs around, still missing on number 1. Changed injectors around, still missing cylinder 1. I've changed the coil to no avail. Then a compression test, that showed nothing, all ok. Then sprayed brake cleaner around looking for intake vacuum leaks but nothing, also cleaned the throttle body. After coming to a dead end I took it to VW in Fairfield to be a analysed. They must have run al the tests, said it was only showing "misfiring code" whatever that means, I didn't need a computer to tell me that! They also put a valve cleaner through it but still missing on number 1. They suspect it's got build up on the valves so need the cylinder head off. I'm not so sure.
The symptoms are - it idles rough and I can remove the electrical connector to injector 1 with no change, then I I slowly increase revs the miss goes away, between 1500-1800 revs, then it comes back again at idle. Sometimes when I drive it on the open road I feel it miss a bit but otherwise it's ok at revs. Anyone got any ideas to check next? Any tips appreciated. Ta.

[Umai Naa!!]

Could be a break in a wire in the harness for that injector.

What's the inside of the distributor cap look like?

[Nevalenko]

Thanks Umai Naa. I've checked the distributor cap and rotor and cleaned the connections, but really that's something VW should be able to find. The broken wire is an interesting one. Do you think the idle should drop or get tougher if I put the lights on to draw a bit more current? I'll check that this morning. Question? Do you think it could be caused by carbon build up on the valve in cylinder 1 like VW suggest? I would have thought it would show up on compression test or be running rough at revs if that were the case, but if I can't find anything it might need looking into further. I've put a cleaner through it and it seems to run a bit better but that's what they do anyway. Any ideas on how to check the valve condition? It's only done a tough over 100k but from what I gather it was all short running.

[pontiff]

Thanks Umai Naa. I've checked the distributor cap and rotor and cleaned the connections, but really that's something VW should be able to find. The broken wire is an interesting one. Do you think the idle should drop or get tougher if I put the lights on to draw a bit more current? I'll check that this morning. Question? Do you think it could be caused by carbon build up on the valve in cylinder 1 like VW suggest? I would have thought it would show up on compression test or be running rough at revs if that were the case, but if I can't find anything it might need looking into further. I've put a cleaner through it and it seems to run a bit better but that's what they do anyway. Any ideas on how to check the valve condition? It's only done a tough over 100k but from what I gather it was all short running.

Where is Melbourne are u? I have a spare injector loom... (And everything else) come over and we cAn work it out

[Nevalenko]

Thanks Pontiff. I'm in Kew and If you're close by and available maybe Sunday? I'd like to check the wiring although I've checked it visually and found nothing irregular. Does anyone know if the Knock sensor could cause this problem?

[pontiff]

I'm out in Pakenham... I'll check and let u know... I have just wrecked a 6n2, so just need to see what I have left . I'm pretty sure I have an injector rail as part of it