Phantom S3 Misfires Logged - coilpacks?

[jimbobery]

Hi,

I had my car vagcom'd a month ago and it had some misfire codes logged, but because I hadn't had the car long I cleared them down to see if they reappeared...

... and they have:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16687 - Cylinder 3 Misfire Detected
P0303 - 35-10 - - - Intermittent
16688 - Cylinder 4 Misfire Detected
P0304 - 35-10 - - - Intermittent
16686 - Cylinder 2 Misfire Detected
P0302 - 35-10 - - - Intermittent

I also did some real-time logging for misfires (think it was measuring blocks 015 and 016), and over a 10 min drive cylinder 2 and 3 misfired briefly a few times.

The thing is, the car doesn't feel like it misfires at all, it accelerates through the rev range really smoothly, no apparent loss of power etc.

I have some other slight issues with the car but not sure if they'd be related:

· On cold start-up the revs fluctuate by 30-50rpm, but only for about a minute, I guess during the EGR period?
· Water temp will get up to 90 after a while, but if I'm cruising at 50-60 for a while with no hard acceleration the temp drops right back to 60, thermostat stuck open?

So I've spent ages reading posts about misfires and coilpacks and in all of them when a coilpack dies the misfires are really noticeable; but my car seems fine?

Any ideas about what to do would be great? I could just leave it but would rather fix it now before it proper breaks!

[Longman]

The erratic idle and water temp sounds like a coolant temp sensor. These are really cheap to change. You want a green topped on as the black ones are notorious for failing.
This might help:
http://forums.vwvortex.com/zerothread?id=1287042

With regard to the missfire, its strange that they are not very noticeable when you are driving. I would perhaps monitor it for a bit, see if it gets worse or more frequent. Coil packs would be my first guess but it might be a wiring problem.

[jimbobery]

Cheers Longman. I think I'll get a new temp sensor today then, I've seen there not difficult to change.

This morning I used code 51 on my climate control to show coolant temp, and it was always about 10-15 DegC below the temp showing on the dash. This is evidence enough the sensor needs replacing I guess?

[jimbobery]

Read some more posts today and some people use 49 on the CC (Climate Control) to show coolant temp so I tried that on the way home from work and the dash temp matched the temp reported by the CC, so now I don't know about the temp sender being faulty.

Can anyone confirm what 49 and 51 do on a facelift CC?