Megane tdc sensor

[dragonheart]

Simply question.

Will a failing tdc sensor cause engine misfire?

I am aware it causes starting issues and the engine to cut out when it completely fails.

My wife's car has now become slow to start and will misfire under load.

Any advice welcome.

[JAHetfield]

What engine is in it?

DCi, I would be inclined to say a problem with the fueling system. The system is so finely tuned that one fill of bad/dirty diesel can ruin the pump/injectors. Also worth pulling the EGR valve out and giving it a clean, I've lost count of the number I've changed.

Petrol, first thing I would do is pull the plugs out and check their condition. Coil packs have also been known to fail.

A faulty crankshaft sensor usually means the engine will either die out completely or just fail to start. The first thing I would do would be to get it on a computer and run a diagnostic scan. If the sensor is playing up, a fault code will be logged in the ECU.

[SpeedMattersNot]

If it's it's a 1.6 petrol it'll most likely be an ignition coil. I've replaced over 1000 in my life I reckon lol

[dragonheart]

It's the dreaded 2.0 ide petrol engine, but please no one tell me it's a fuel pressure regulator issue, already checked it out.

Just want to know if the tdc sensor starts to fail could it cause the car to misfire under load.

[SpeedMattersNot]

In my opinion, no.

I would've suggest the common FPR issue though.

No fault lights?

[dragonheart]

No warning lights on. Pressure regulator recently replaced. The car runs and drives fine, ticks over at a steady 800 rpm with no misfires. If you press the throttle in slowly as you drive it will not miss and will pull strongly through the rev range, however if you stamp on the throttle it will misfire before clearing itself and then continue to pull strongly through the revs.

[SpeedMattersNot]

When were the plugs last checked/changed? Are they Renault approved?

[dragonheart]

Last service was June 2011, full main dealer history/specialist(K-Tec racing) history, only ever used genuine parts.

[dragonheart]

Should of said, had the car on the diag, only fault showing was for the flywheel (tdc) sensor. Did a quick visual and the car is fitted with the later blue sensor which would indicate that it had been changed at least once before.

So i was wondering if the fault code stored in the memory relates to the current misfire or weather it was not cleared after the tdc was replaced last time.

[SpeedMattersNot]

Sorry mate.

On paper, it could give a misfire, but experience and logic says if the fault only appears under load - that rules it out.

If it's not flagging up a sparky fault, then it'll typically be a non sensored item.

Dodgy fuel? Fuel filter? Again I'd just take a look at the plugs...At least you might get an idea if the issue is across all cylinders or isolated to one bore.

Again - I believe FPR issue is still on-going AFAIK!

Sorry, my knowledge runs out there. Wait for jimtech to come along, he's actually still a Renault technician, so hopefully he's upto date with the latest situation with the IDE engine faults.

GL and keep us upto date !

[dragonheart]

Ok mate, thanks for your advice.

Might change the plugs and fuel filter again this weekend as a matter of course, can't do no harm.

Funny you should mention dodgy fuel, as we have recently started using tesco unleaded. Might also try switching back to V-power.

[dragonheart]

Well removed, cleaned and replaced the tdc sensor, which was like new, no difference. Car still has misfire under load. Next step replace all 4 plugs with genuine renault items.

Going to take things one step at a time so hopefully i will be able to find out which fix solves the problem.

Updates to follow.

[dragonheart]

Misfire now fixed, turned out to be worn ignition leads, the spark was tracking down the plug shaft under load and causing the misfire.

While it was in my local garage i had it fully serviced using genuine Renault plugs, Bosch filters and Mobil 2000 x1 semi synthetic 10w-40 oil.

Car now running like a dream.