99 1.6 16v. Misfire / vibration after wet coils - 540iV8
When filling the washer bottle from a garden hose, the hose fitting blew off and sprayed water across the top of the engine. All seemed well and the car ran OK, but when the wife used it (it's hers) the next day, it ran terrible and she ended up abandoning it!

I brought it home running on one or two cylinders with loads of misfires and white smoke. When I got home, the flexi on the down pipe and the front of the cat were glowing cherry red and the insulation on the front bulkhead was smouldering! Unburnt fuel in the exhaust.

I have dried out the coils and cleaned the plugs and the engine starts fine and runs fairly smoothly when cold. When it's up to temperature, it bobbles a bit and sound like theres a slight blow from the right hand cylinder plug chamber (but this could be from anywhere and misleading). In reverse gear, the drive seems OK and the car doesn't grumble, but when going forwards it's different. On first picking up drive and then again at about 4-5000 rpm, theres a terrible vibration that comes right through the car and the car seems a bit down on power (although I don't drive it often and am comparing it to my own car). There are also rubbing marks on the downpipe where it's been touching the front anti-roll bar and steering gear. (These could be from the initial problems when the egine was VERY rough).

There's plenty of pressure at the tail pipe when on idle, although initially there wasn't and I thought the cat might be blocked.

I've read various posts in the forum and suspect either cat or MAP (or MAF don't know which on this engine) hose connections, but (a) can't find MAP sensor hoses! and (b) don't want to start breaking the exhaust into pieces until I've eliminated everything else as access is awkward and bolts WILL BE seized!

Any ideas or help????? photo of MAP / MAF locations appreciated.

Edited by Dynamic Dave on 25/11/2008 at 00:04

99 1.6.16v. Misfire / vibration after wet coils - Screwloose
The pencil coils on this engine fail in droves even when they don't get wet.

Once the coils have established [burned] a track down the plug's insulation, it's going to be very hard to get them to stop using it.

The oxygen sensor in the exhaust [and the cat] may well have suffered too. This really needs plugging-in and having the sensor and misfire data examined for clues.

Edited by Screwloose on 19/02/2008 at 21:07

99 1.6.16v. Misfire / vibration after wet coils - colin324
The coils will cause a bad misfire, especially when under load, along with rough idling when warmed up. On my megane, the coil on cylinder 4 was tracking after going through a huge puddle. It was ok idling cold, or with the aircon on, when warm it was lumpy and hunted. Once past 2500rpm it was ok. If yours doesn't clear with revs, then it is possible more than 1 coil involved.

I removed the coil packs and then vacuumed the spark plug bores. Take out the plugs and check their colour/condition. The should be a grey/beige colour (not black). This may point to the coil pack in question. Clean the bore out using WD40 and a rag. Then use WD40 or a silicon lubricant spray, and clean the coil extensions (Mine was a rust colour on number 4, until I cleaned it off with WD40). Reassemble, and try restarting. My car was like new afterwards. If there is no difference, you may need to replace one or more of the coil packs (about £20 each from good aftermarket suppliers). Don't use any agressive cleaners (carb cleaner, brake cleaner, etc) as this will damage the rubber/plastic and may cause a permanent fault. Silicon based products will condition the rubber and improve the voltage breakdown.
 

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