Renault Laguna (1994 - 2001) - 1997 2.0 8 valve petrol engine vibration/misfire.

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Wed 2 Jul 2008 12:53
1997 2.0 8 valve petrol engine vibration/misfire. - sawf93
I have a high mileage, 1997 Renault Laguna 2.0, 8 valve petrol, which has developed an engine vibration/misfire starting at about 2000 revs. It has done this three times whilst I've had it. The causes were:- 1.Piston ring failure dropping the compression on one cylinder. 2. Failed valves doing the same. 3. The same again different cylinder.

All were repaired successfully except on the last occasion when the misfire remained, to the extent that cylinder does not even fire at tick over.

All investigations have failed to find a cause - compressions are fine, no obvious bore damage, no leaks, the cylinder head is good and the fuel injectors have been replaced though they were firing properly anyway.

A Renault specialist advised that the engine management showed nothing wrong and suggested that a pattern part coil was a common cause of misfires on Renault engines. They replaced the coil for the affected cylinder, the second coil and the HT leads were later replaced but still the problem persists. Everyone is baffled so if anyone has any ideas they would be gratefully received, before I have to put the car out of it's misery.
Reply | Report as offensive | Link
Wed 2 Jul 2008 14:23
1997 2.0 8 valve petrol engine vibration/misfire. - Screwloose

You have been remarkably - suspiciously - unlucky with this engine? If correct; that catalogue of disasters would suggest that it suffered an "incident" in it's earlier life.

First identify the misfiring cylinder. Then spray a little brake cleaner into the intake at idle and see if that pot starts to fire on it. If so; fuel; - if not; spark, air or compression; so do a running compression test for a sticky valve.

A vacuum gauge on the inlet manifold may show something useful too.
Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide