Few Problems with new car!

[jakejakejake1]

Hi Everyone
I bought a 2005 Megane last weekend for the bargain price of £300. It’s a 1.6L 16V VVT dynamique but it’s got a few problems (obviously, for that price ) and I’m hoping they won’t be too hard to sort out.
Firstly when warm the car idles quite low and the engine rocks/vibrates a lot which can be felt in the cabin. Doesn’t happen on first start up and the car starts fine, only happens once the car has been on for a while and warmed up. I replaced the coils and spark plugs and cleaned out the throttle body as a friend mentioned that these often go and can cause similar problems to what I’m seeing. The car seems to drive OK other than that.
Secondly, the electric sun roof whistles if I got above65-70mph and as well as that when trying to open the sun roof it kind of slides backwards into the rear one rather than lifting itself, it can be opened by pushing up on it when trying to open.
I haven’t tried unplugging the battery or anything as I don’t have the radio code, is there any way I can find out what the code is?
If you need any more info please let me know.
Cheers for the help,
Jake

[freelanderuk]

Hi
There are a few post about changing the nylon bushes on the sunroof on here , to get the the radio code ,take the radio out of the car and post the security code or photo it and paste that on here , engine mounts may need changing, have a good search about the forum you will find most of the answers you need

[jakejakejake1]

Thanks for the help, I ordered new bushes for the sun roof this afternoon so that should be that sorted.
Just got my bluetooth OBD reader in the post after work and its throwing up P0304 and P0300 codes, which are random misfire codes, I guess as a result of the coils. I changed all of the coils and spark plugs yesterday so I'm not sure why this is still showing?
Also a bit of a stupid question but which cylinder is number 4? The end with the throttle or the other end?

Cheers,
Jake

[jakejakejake1]

The plot thickens.
I replaced all of the coils, but the running didn't improve at all.
I have tried unplugging the coils with the car running, the outers cause the car to stall immediately while unplugging either of the centre ones makes the car idle worse, but not stall. Therefore the problem is likely with either cylinder 2 or 3.
I then switched the coils of 1 and 2, and it was still unplugging the inners that was causing the problem.
I then switched the coils of 3 and 4, and it was still unplugging the inners that was causing the problem, leading me to believe it wasn't a coil problem (else the problem would move as the coils were switched around).
Tried changing the (brand new) spark plugs around as well but the problem didn't move.
From the various trial and error testing I believe that cylinder 3 is the culprit for the bas running, but the question is:
Now what? It's not a coild or spark plug problem so I'm unsure what to do, any ideas?

Cheers,
Jake

[freelanderuk]

Do a compression test if you can

[jakejakejake1]

No chance to do a compression test yet as the kit hasn't arrived.

But some update on the problem, I cleared the codes with a blue tooth OBD adaptor and went for a short drive now I have another issue. The new code is P0141 and says it is O2 sensor 2 bank 1. The voltage for that sensor is a constant 1.275V.

Any idea what this could mean? I guess it's the narrow band downstream of the cat, which I assumed didn't affect fuelling?

Cheers,
Jake

[jakejakejake1]

Compression test done and it doesn't look great.

PSI (cyl 1-4)

130
60
60
130

Any idea what this means? and it seems a bit coincidental that the numbers were very close to one another other that the fact the middle two were 70 psi down, seems like a head gasket between 2 and 3.
Also the car makes a kind of metallic leakage noise (psst psst psst but metallic sounding) while idling, so I guess that's the compression leaking somewhere, probably between cylinders.

Cheers,
Jake

[freelanderuk]

Could be worn piston rings,worn valves or valve guides, head gasket, cracked cylinder head, but it is a head of job to find out

[Philthy]

If you're a gambling man who plays the odds, I'd plump for head gasket. It's certainly the lesser of a bunch of evils. If you get the head off, and it isn't the gasket, you're much closer to diagnosing the problem?

[jakejakejake1]

What kind of job is a head gasket on these 1.6 16V engines? I have done the head gasket on my classic mini before but never on an overhead valve engine, is it a do at home job or am I best stumping up the cash for a garage to do it?

Cheers,
Jake

[Philthy]

It's not a job for the faint hearted! There are quite a few things that have to be done properly. Making sure the timing belt is refitted correctly is just part of it.