Renault Megane misfire

John T Carroll

2008 Renault Megane 16V Petrol: Friends Megane emission warning light illuminated on her way home from Shannon Airport last week. I had a quick look today, multiple misfirng up on EOBD code finder, removed all coil/plugs and found heavy evidence of water in No3 plugwell (and some in No4) which had left deposits on No3 coil which was also wet. It looks like rain water ingress, it certainly doesnt look like a head gasket issue as its on the "wrong side" of the head and the expansion bottle isnt losing water. Anyway I cleaned up the coils, inspected the plugs which were all perfect and boxed it up. Code cleared and engine now running fine. Has anyone come across this before?, I am not familiar with Renaults.

Interslice

Was it from the washer jet leaking maybe or the bonnet left open or coolant spilt onto the engine?

I remember the first plug change a mk2 here and it having a mixture of oil dirt and water in the tubes because the seal at the top of the coil wasn't sitting right. Load of dirt, leaves and the little feckin sycamore flying seeds retaining water and condensation at the top of the rocker cover. Blocked scuttle panel too at the time, might have caused it.

John T Carroll

Interslice wrote: »

Was it from the washer jet leaking maybe or the bonnet left open or coolant spilt onto the engine?

I remember the first plug change a mk2 here and it having a mixture of oil dirt and water in the tubes because the seal at the top of the coil wasn't sitting right. Load of dirt, leaves and the little feckin sycamore flying seeds retaining water and condensation at the top of the rocker cover. Blocked scuttle panel too at the time, might have caused it.

Thanks for those tips, especially the one re the washer jet, it was like the Artic Circle up here yesterday so I didnt spend any time looking for the culprit(s)....will post back re findings.

Esel

Very localised water alright! Was the car parked for a while into the wind/rain?

Washer jet tip sounds promising too.

John T Carroll

It was parked up at Shannon for 16 days.

Edit: Had look at it this AM and found the rubber sealing strip nearest the windscreen detached so hopefully that was the problem.....also tested windscreen washer hoses for leaks, none evident.

steveshort

My Megane had the very same problem

I replaced the coil pack and it was sorted, never discovered where the water came from though, but it hasnt returned after 16 months.