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misfiring megane

I have a strange intermittent problem with my p reg 1.6 megane.

The engine will be running fine and then it will start to misfire badly, sometimes almost dying to the point where I have to floor the throttle to get it to pick up again. At idle, revs will fluctuate up and down between about 500 and 1250 in a regular pulsing pattern, sometimes cutting out all together. Switching off and starting again eases the problem for a few seconds and it seems worse when the engine is warm.

It's not doing this all the time, It may go for a few days running perfectly and then it will be bad for a few days.

I suspect one of the coils, or the tdc sensor. My leaning is to the tdc sensor as I'm not sure the coils would act intermittently in this way. I have heard that the Renault tdc sensors can play up intermittently.

I'd appreciate any advice on whether this seems reasonable to you or whether there is a way that I can diagnose the problem more accurately

Thanks

Neil

Reply to
Neil
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For every Renault tdc sensor that dies there's about 7988 coils that give up the ghost.

John

Reply to
John Greystrong

Ahhh thanks John. Do you have any idea how I can identify which of the 2 coils may need to be replaced?

Neil

Reply to
Neil

Do they still have that stupid power box tucked up the inside of the wheel arch area that splits its lid and kills the engine when it gets wet?

PDH

Reply to
Paul Hubbard

Agreed - coils are frequent failure points on these cars, with those exact symptoms. You can only really test the electrical resistance of the primary and secondary windings and see if they are in-spec. Even so they may be when they are cold which makes life difficult.

J
Reply to
Coyoteboy

Or take the car out a drive with a spark plug in the ashtray. Wait til it's misfiring badly, stop the engine, pop the bonnet, whip a lead out and stick the plug in the end. Rest plug against metal body and crank while looking for spark. Lack of spark = pumped coil.

Reply to
Sandy Nuts

Ahhh that's worth a try. I have one of those connectors that you can put in-line between the HT lead and the spark plug that flashes every time there's a spark. I could put that on each cyl in turn and drive till it's missing, then just pop bonnet and look.

Thanks to all, I'll let let you know the outcome

Neil

Reply to
Neil

OK, just changed the coils (both) and the HT leads and the problem is still there.

Any suggestions as to how I can identify the problem - I'd rather not spend another bundle of £££s without being sure of th eproblem

Thanks

Neil

Reply to
Neil

Just had a computer analysis of the engine management system done.

It looks like there is/was a wiring problem between the MAP sensor, the TDC sensor and the throttle position sensor. Moving the wires and disconnecting them and reconnecting them to the units has cured the problem for now.

Apparently if the problem recurs, it'll be time to strip down the harness in that area and look for a broken wire.

Neil

Reply to
Neil

...or corrosion in the connectors.

Reply to
Conor

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