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Discussion Starter #1
Hi guys,

Very frustrated with my Megane 1.9 dCi 120 by now.
Basically the car is down on power and it is hard to get it over 2000 rpm. I can get it to 3000 rpm in first and in second gear but once I go past 3rd gear it is very hard to get the car past 2000 revs.

This is what I have done to the car so far:
Changed MAF as car was sluggish on low revs and smoked black smoke a bit. That cured it and it was going fine for a while.
The car then started smoking blue smoke and I could smell burned oil. The car also became very very very slow on low revs. It would be hard to take off sometimes but once it reached 2000 rpm the car felt OK except for the smoke. So I though that the turbo is gone and changed it. This didn't do anything. Next I checked the egr valve (I know I should have checked it before changing the turbo...) and it was VERY VERY dirty. Cleaned it and it helped a lot and I could drive it.. The power didn't feel as good as it felt on the old turbo but it seemed to be OK. Then after while the power just dropped and it's been like that since. I have tried another MAF, another EGR valve, another boost solenoid. Brought it to indie mechanic who done diagnostics twice. All clear. I also cleaned the Inlet Manifold which was very dirty too. The car is still very sluggish after 2000 revs and I have run out of ideas what could be wrong with it. Could anybody advise me on what could I do next???
 

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It sounds like the ECU has dropped into limp mode.

Have you any warning lights on the dash?

Has the MAP sensor and its wiring connection been checked?

Also is there ny smoke from the exhaust and if so what colour is it?:)
 

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Discussion Starter #4 (Edited)
No warning on the dash. I'm not sure if it's normal but when I scroll through the on board computer it says No Message Available.
Do you mean MAF sensor instead of MAP sensor? If so yes, I have tested 3 different MAF sensors on the car. Whenever I unplug the sensor and drive the car it spits out a lot of black smoke but I don't feel any change in power.
It is a little smokey. I can see some smoke coming out when I drive at night and there is a car behind me but it's very minimal as I don't really see and smoke when I drive during the day. Although the car does spit some smoke out when started from cold. It would spit out blueish cloud of smoke and run normally.
 

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I mean the MAP sensor - sometimes referred to the turbo presure sensor.

Unplugging the MAF sensor forces the ECU into default mode so it definitely looks like the fault is elsewhere.

Also Renault use a different protocol than most other European makers in their ECU's so your code reader may not be compatible.

I take it you have checked the fuel filter for the dreaded metal filings?:)
 

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Discussion Starter #6
Also, the car seems to have most power when I have throttle half way pressed. If I press full throttle it seems like the car is struggling but when I release to to about half way I can feel bit of power kicking in.

Just did a quick test drive with EGR valve plugged out and it made NO difference whatsoever. Could it be faulty EGR valve? Do the EGR valves need to be coded to the car - something that the guy who did diagnostics said?
 

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Discussion Starter #7 (Edited)
I mean the MAP sensor - sometimes referred to the turbo presure sensor.

Unplugging the MAF sensor forces the ECU into default mode so it definitely looks like the fault is elsewhere.

Also Renault use a different protocol than most other European makers in their ECU's so your code reader may not be compatible.

I take it you have checked the fuel filter for the dreaded metal filings?:)

Do you mean the little sensor that has 2 vacuum hoses going in to it?
The guy who did diagnostics uses Delphi unit and it did pick up faults that where not related to the issue (Airbag fault) so I guess that he would have picked up any other fault codes if there where any? Or would it be possible that not all fault codes are picked up by his unit and I would have to go to Renault dealer to pick up all codes?

And no, I haven't checked the fuel filter for any metal residue. Could faulty diesel pump cause these symptoms? As I was saying it feels like turbo is just not kicking in...
 

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Discussion Starter #8
I'm just wondering, what would be the symptoms of clogged CAT? Could that be the case in my car? It looks like the previous owner had replaced the turbo before me and it looked like he was driving it with faulty turbo for a while before replacing it. Could that have clogged the cat? I mean the amount of dirt on EGR valve and in Inlet Manifold was unreal...
 

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Discussion Starter #10
Actually, I was removing the MAF sensor again today and I noticed there was quite a bit of soot in the pipe where the MAF sensor is located. It smelled strange, not like diesel, more like burnt oil smell. Not sure if this is relevant to the power issue...
 

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as you look at the turbo theres a threaded bar cooming from the housing to a metal housing looks like filter but its a valve controls the operation of boost if this is stuck or torn could be the problem as you probably have changed the boost actuator?
 

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A sway gate is another name for a wastegate.

If a recon turbo has been fitted it will come with a wastegate and its actuator but as laready said check it is moving when the engine is revved.

The wire elements inside the MAF should be perfectly claen and any sign oif them being contaminated is not a good sign.:)
 

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Discussion Starter #15
A sway gate is another name for a wastegate.

If a recon turbo has been fitted it will come with a wastegate and its actuator but as laready said check it is moving when the engine is revved.

The wire elements inside the MAF should be perfectly claen and any sign oif them being contaminated is not a good sign.:)
Hmm, I think the wastegate could be the problem... I think I looked at it and it wasn't moving when the engine was revved. Not sure, I will check it again an report back. MAF is definitely not the problem, I have tested 3 MAF sensors and the problem remains the same. Even when I disconnect the MAF the car remains the same it just starts smoking black smoke.
 

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Discussion Starter #16
I have looked at the wastegate and yes, it's not working. The little leaver on it doesn't move at all compared it to another laguna that has the same engine and it moves about one inch once the car is started. Anyway, I will be taking the turbo off to see if the wastegate is the problem or is there a problem with the turbo itself that it doesn't allow the leaver to move. I'll report back if that has been the cause of the problem.
 

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Discussion Starter #20
I used the other turbo that I had. Can you screw the nut back on without taking the turbo off? The space is tight but it should be doable.
 
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