Help please. My 2002, 1.4, 16v Clio misfires at tick-over once hot, and sometimes when pulling up a hill unless I keep the revs up more than necessary pre-misfire. The misfire is not noticeable at cruising speeds, nor is there any noticeable drop in power when it isn't actually misfiring!
I believe the misfire relates to the engine running rich on cylinder 3 (numbering from gearbox). My rich running diagnosis comes from spark plug colour of dark, matt grey in cylinder 3 only. It is not oily or otherwise fouled in any way. The other three plugs are all a light tan colour.
I have tried the following. Swopped plugs, the rich running plug becomes light tan in its new cylinder while the plug substituted in cylinder 3 becomes dark grey. I have also swopped the coils and injectors from cylinder 3 to other cylinders. Nothing cures the misfire or moves the rich running from cylinder 3.
Could it be an ECU fault? Seems strange to affect only cylinder 3? Could it be injector wiring? I would have thought a wiring fault would tend to make the cylinder run weaker rather than richer by failing to open the injector? Could it be ignition wiring? A poor connection could presumably result in a poor spark? I do own a multimeter but am unsure how to check the ignition wiring with it. Any suggestions welcome.
FYI: I live in New Zealand where Renaults are scarce. I have not taken the car to our Renault dealer to check the fault codes or repair as 1) I have no faith in the dealer - asked to replace cambelt and water pump they said the water pump didn't need replacing; guess what failed within the week, and they then wanted to charge me more labour! 2) they charge like wounded bulls, over 100 pounds sterling for a single coil.
I believe the misfire relates to the engine running rich on cylinder 3 (numbering from gearbox). My rich running diagnosis comes from spark plug colour of dark, matt grey in cylinder 3 only. It is not oily or otherwise fouled in any way. The other three plugs are all a light tan colour.
I have tried the following. Swopped plugs, the rich running plug becomes light tan in its new cylinder while the plug substituted in cylinder 3 becomes dark grey. I have also swopped the coils and injectors from cylinder 3 to other cylinders. Nothing cures the misfire or moves the rich running from cylinder 3.
Could it be an ECU fault? Seems strange to affect only cylinder 3? Could it be injector wiring? I would have thought a wiring fault would tend to make the cylinder run weaker rather than richer by failing to open the injector? Could it be ignition wiring? A poor connection could presumably result in a poor spark? I do own a multimeter but am unsure how to check the ignition wiring with it. Any suggestions welcome.
FYI: I live in New Zealand where Renaults are scarce. I have not taken the car to our Renault dealer to check the fault codes or repair as 1) I have no faith in the dealer - asked to replace cambelt and water pump they said the water pump didn't need replacing; guess what failed within the week, and they then wanted to charge me more labour! 2) they charge like wounded bulls, over 100 pounds sterling for a single coil.
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