Megane DCI nightmare

[dannyb1986]

Hi, I am new to the forum and was wondering if you could help.

I have had a megane 1.9 DCI for a few years, been a pretty good car, but not without a few problems.

It started around a year ago and occasionally would come up with "check injection" when driving and lose power, when turned off and on it would be ok for a while. I never did anything with it as it was so intermittent. Then a few month ago the turbo was noisy, it didnt run off its own oil, i switched it off and didnt run it. I removed the turbo and the inlet side bearing had collapsed. I bought a reconditioned turbo, with new gaskets and oil pipe. I have fitted it but had problems since. I fitted it and drove it and it had no power. I checked the vac pipes and think i had rooted them wrong, I think they are right now but not a 100% sure. I have drew a diagram as to how i have got it.

1) I still have no power and "check injection" on constantly. I have got a code reader, read the code P0409, which is EGR, i have cleared it, but still got the ligtht on and now the code reader says no codes.

2) The turbo actuator never moves on start up or engine off.

3) the vac pipe to the actuator has vacuum there, but not much.

4) there is small valve under the vac reservoir, it has 3 pipes connectors, but i only have 2 pipes to go to it!

I know its a long story but wondered if anyone can offer any help or advise, I have been trying to find someone with the same car to look and see if the same but cant.

[AlexB]

The actuator is supposed to move within seconds after starting the engine. Therefore, the problem is with the pipework or the solenoid valve. Does the actuator move when you apply vacuum to it directly? Have you seen the factory manuals in our sticky thread above this one?

Please don't use the oil which you used before, and change it twice as frequently as before.

The EGR valve. It needs cleaning. It was soaked with oil when the turbo seal failed, and then soot stuck to this oil...

[dannyb1986]

The oil never made it near the egr, it was the compressor side thst failed, not the turbine. I changed the oil and filter. Im borrowing a mityvac tonight, going to see if the actutor moves manually.

[dannyb1986]

Hi all.

Can someone please check the vac pipes on their cars and let me know if I have them correct please?

[mickeybo]

The turbo on your megane is designed to give to give boost immediately which gives the engine low speed torque. When vehicle is started hot or cold the turbo actuator rod should fully retract. It needs to see a vac reading of approx. 25/26 inhg. Now this is where your mity vac comes in handy I would disconnect vac line at turbo actuator connect vac pump to actuator using vac pump on actuator observe to see if turbo rod starts to retract at approx. 3 to 5 inhg and is fully retracted at approx. 18 inhg You would need to keep the mity vac connected like this for approx. half hour to see that theres no drop in vac which would point to a faulty diafram within actuator.Hth Regards Mickeybo Derry N/Ireland

[AlexB]

Please have a look at the page 442 in the manual. The connections in your diagram may be different unless I am missing something. There are also relevant pictures in p.445, 468, 474, 485, 558. Start with 558.
https://ray-lee.co.uk/megane/dialogys/MR364MEGANE1.pdf

The engine stop throttle, for example, is supposed to be connected to a solenoid valve. The pipes around the tee need to be checked.

[mickeybo]

The turbo control valve on your diagram has only shown 2 ports instead of 3 as it must have.These are known as dump valves when these valves are activated vac travels through top inlet port & out the 1 directly below. These top 2 ports are known as 1 & 2. The 3rd port very bottom 1 is the dump port to atmosphere. When the ecu detects the turbo is going into over boost it switches the valve off. Meaning no vac from 1 to 2 but switches to 1 & 3 bottom port to atmosphere. On these vac controlled systems it's imperative that any connectors like rubber elbows which have a habit of splitting must be a tight fit Regards Mickeybo Derry N/Ireland

[AlexB]

Diesels don't have a dump valve for an obvious reason.

[mickeybo]

Danny boy b 1986 on his 4th question wanted to know valve under vac reservoir has 3 pipe connectors but only 2 pipes connected I answered by pointing out that this is a turbo control valve commonly known as a dump valves. These valves are used on all vac operated turbos . On less most of the later turbos are allied signal which work on pressure (exhaust gases) Regards Mickeybo

[AlexB]

Hi Mikeybo,
I know what you mean: in order to control the actuator of a VGT or wastegate turbo, one needs to reduce vacuum in the actuator occasionally, which calls for the 3rd port on the control valve. It is a kind of dumping the vacuum... Still, it is not a dump valve, whose function is to dump the boost pressure when the throttle is suddenly closed after the full boost in a petrol engine.

[Strickland418]

The Megane DCI nightmare is a real problem for many owners of this car. The high cost of repairs and the inconvenience of having a car out of service for long periods of time can be very frustrating.

If you are experiencing problems with your Megane DCI, it is important to get it diagnosed and repaired as soon as possible. Driving a car with known problems can be dangerous and can also lead to further damage and even more expensive repairs down the road.

If you are considering buying a Megane DCI, it is important to do homework help your research and be aware of the potential problems. It is also important to factor in the cost of potential repairs into your purchase decision.