Megane cutting out

[Paul79]

03 plate - 1.6

Basically the last couple of weeks it has been hesitating slightly when starting and the alarm has been going off randomly.
However today i started it and it just died. The needle on the rev counter just dropped straight down and the engine cut off. Only does it when the engine has been left for 10 minutes or so.

Any ideas please?

[AlexB]

My first guess is the TDC sensor, the second is the missing hatch cover on the left front wheel arch liner, and the third is the battery.

Read the fault codes (search for elm327 on ebay) and provide more information about the car's history for anything better than a blind guess.

[Paul79]

Never heard of the wheel hatch thing? What exactly is the problem with that?

TDC - I have read a lot on this and is it an easy job to change?

As for the elm327. Is this equipment that will give you a fault code? If so do you need any extra software with it?

Ta

I am not very well up on cars as you can see.

[Paul79]

Just an update.
I'm not a happy bunny.

Got it checked out by a garage who claimed it needed a new battery and that it was ok again. I had my doubts but anyways i picked up the car and for a day it drove well again.

Today the problems have started again. Starting from hot it doesn't always start first time and i had the dreaded whilst idle the revs dropped again and the engine cut out.

So a new battery had it going again but now i am back to square one.

Any more help would be great.

I have it booked in on the 20th at Renault but in the meantime would love some advice.

Thanks ( stressed out )

[AlexB]

Paul,
You'll end up doing what I suggested anyway...
BTW, what fault codes did the garage extract from the ECU? Otherwise, why didn't you ask about it?

[Paul79]

Well i was a bit naive. And i know very little about what i am talking about.

Basically the garage told me that the battery needed replacing and they couldn't read any codes because of a duff battery.
I just accepted that as that.

If it is any of the things you have suggested how much am i looking at forking out?

It's in Renault on the 20th for a check then they will take it from there and i am dreading it.

[AlexB]

This could only happen if they discharged the battery completely by leaving the ignition or lights on. What codes did they read after replacing the battery? Ring them tomorrow and ask for the exact codes and exact interpretation of them.

Have you checked the hatch in the liner which I mentioned earlier? The fuse box behind it can be responsible for the alternator not charging the battery properly. There is some electronics in it and it is connected to the CAN bus network.

[Paul79]

I don't know what you mean by 'hatch in the liner'.

Please can you help explain to a novice.

[AlexB]

I mentioned it in my first reply. Look in the gap between the front left wheel and the wing. There is an access hatch under the wing for accessing the light bulbs. If its cover goes missing (often due to negligence of a garage), then spray from the wheel enters the engine compartment and causes electrical failures.

[Paul79]

Cheers Alex. Will have a look and see if it is missing. If so are they easy/cheap to pick up and fit?

You have been a star.

[AlexB]

Fitting is simple, just push it in and twist. I don't know the price -- check it first.

[Paul79]

Well just checked and if it is a piece of plastic that goes all the way around the arch i have them on both sides. So i guess that counts this out.

At the moment i am having to drive it due to work so i am just hoping it doesn't pack up completely or i am screwed.

[AlexB]

There is a hatch in this plastic part. It is small, about 15cm in diameter. It is on the front side, closer to the headlight. Anyway, you did not see a hole, so it's probably in place.

The next question. Let's assume that you are now experiencing the same fault as earlier and that the garage was right regarding the battery. Is your battery badly discharged now? Look at the cabin light while flashing the headlights. If it dims noticeably, then the battery is flat again. Try this, before guessing further.

[Paul79]

I seen circular plastic bits with like a twist thing to open the covers so i presume that is what is supposed to be on the arch.

As for the battery just checked the light and no noticable difference. I don't know if this has anything to do with it but now the alarm has started going off again randomly for no apparent reason.

It is doing my nut in now and with Renault being so busy i can't do anything for 18 days and i don't know if i trust going to any other garages.

[AlexB]

Relax, Paul. It's a petrol naturally aspirated car. They are simple, one just needs patience, manual (as in our Links section), a bit of experience (our forum) and the right tools (elm327 from ebay)...

Let's start again. Initially you had a few weeks of starting from cold problems with no warning lights. The battery died, possibly due to excessive use. It was replaced, the car was warmed up and returned. You drove it for a day, then the hot start problems started without any warning lights. This is the 1.6vvt engine...

Cutting off without warning lights and stored codes in this engine is often caused by the dephaser. Have you ever heard a loud noise on startup? --*

Another known offender is the TDC sensor. It also leaves no traces. They are easy to replace.

Coils, camshaft sensor, dephaser valve, O2 sensors -- they all leave a record in the engine computer.

MAF sensor is not used during starting, but after that it kicks in.

Intake air temperature sensor can be read by using elm327. Check what it shows.

Fuelling problems -- not very likely. The throttle body -- the idle mode is affected, but it still starts. Vacuum pipes -- engine revving -- no.

A power/ground wire somewhere -- loose contacts are possible...

I don't know, answer the first question marked with (*) first.