cut out after start up

[jamie8824]

hi im after some help

i have a 2005 1.4 petrol megane

the problem is when i start up from cold the car cuts out straight away unless i press the accelerator until it is warm. once the engine is warm it does feel like it is going to cut out but doesnt. also once driving the car feels like its being held back. no lights or faults on the dash. i have had the car in a garage for a couple of days and they say that they are sure its the injectors all 4 of them at fault at a price of £550. does this seem right or is it a common fault and is there anything else i can try before i give the garage the go ahead thanks in advance

jamie

[craigyt]

Is it fly by wire throttle?

[jamie8824]

yeah sorry i thought they all were now

[craigyt]

Id take the throttle body off n clean the gunk out from round the butterfly, might help cos its worse when cold it will be thicker than when its warmed up

[jamie8824]

cheers im going to collect the car and ask a mate to give me lift i just carnt see how all 4 injectors can need changing when there is no lights on the dash and it does still drive of a fashion thanks for your help

[l111fsh]

The chances of all 4 injectors going belly up at the same time are massively high. If they have, hell, get your lottery numbers in.
I work mainly with diesel engines but a petrol runs on the same principle. By the sound of it the throttle body may be gunked up (as mentioned previously) or possibly the cold start aid is acting up. Does the vehicle start ok after it has got upto working temperature?

[jamie8824]

Yeah that's what I was thinking surely if all 4 had gone it wouldn't start. Once the car is warm it does start ok but the tick over is a little low. I have just ordered a coolant sensor and some contact cleaner and at weekend it's getting a going over I have heard about cleaning the throttle body so I carnt hurt to have a look

[l111fsh]

has there ever been any fuel contamination in the past? Fuel pump would be a common factor in all that, but checking the fuel sedimenter/agglomerator would be a great place to start. Unscrew the little valve at the bottom of the fuel filter, if clean fuel comes out good, if crap comes out it's a good indicator of restriction to fuel flow.

[jamie8824]

I don't know about the fuel but is a petrol so the filter doesn't have anything like a bleed point it's just a basic fuel filter with pipe in and pipe out

[AlexB]

It is very unlikely that all four injectors have failed in the same way, unless someone fed mud straight into the fuel line.


Start with cleaning the throttle body and checking the intake for vacuum leaks. Check/replace the air filter.

Then make sure the fuel is good and that the tank is not contaminated with water of gunk.

Then check the fuel pump and the fuel line.

The further actions will include checking the compression, oil quality/consumption, timing belt, etc.

It would be more than helpful to read the OBD codes and plot the live diagrams from the sensors while replicating the fault. It makes sense to start with this, but something tells me that the common sense will be held back...

[jamie8824]

Thanks very much for the advise I've got the car back now and I'm going to clean and check a few things. When I asked the garage they said there were no faults shown up on there computer and he even said the fuel pressure was bang on so I will just see how I get on

[AlexB]

As the garage people have looked at the engine, this eliminates the most obvious and trivial problems. My money would be on cleaning the throttle body. You see, soon after starting the engine, it goes into the closed loop control mode, where the mixture and throttle are adjusted automatically. This does not happen on the cold engine immediately - this is when you observe the problem. This is why I suggested to use the OBD system in an advanced way, but your garage probably does not employ suitable people for this...

Anyway, start with cleaning. As I remember, there were some instructions on how to do it in the technical notes in the sticky thread. Do not spray the carb cleaner on any electrics, and replace a gasket somewhere. I don't have the technical note at hand now.