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Discussion Starter #1
Hello,

I own a 2003 Laguna 1.9 dCi expression with around 72000 miles on the clock.
Over the past couple of weeks I have noticed a repeating power surge at around 2500 rpm, this is not strong enough to actually slow down the car but I can feel it like a pulse whilst I’m driving the car. When the car is loaded this pulsing is heavier.
I'm not sure if this is connected but I also tend to get quite a bit of smoke coming out of the exhaust.
I took the car to the dealership, they checked out the fault history which showed a Top Dead Centre sensor fault, but said they couldn't feel the surge on a test drive. They replaced the TDC sensor and glow plugs (I thought the glow plugs were just for start up, but the mechanic assured me they are in use all the time the engine is running), they charged me £500 but could not guarantee to fix the fault. Surprise surprise it didn't fix the fault.
I’m not sure what to do next. I don’t want another costly experience with the dealership who doesn’t think there is a problem, but I do need to fix it!
Any help on this would be much appreciated, thanks!
 

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Hello and welcome to the forum.:)

I'd start by cleaning the EGR valve.There are details on how to do this on the forum,so if you a search you should be able to find the relevant info.

If that doesn't cure it,get back to us.:)
 

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Discussion Starter #4
Look what I found

Today I took a look at the EGR valve, I had trouble getting it off so to get better access I removed (what I believe is) the throttle valve housing/damper unit and found that the o ring seal had been trapped, (see photo).
Further examination of the housing revealed that the body was cracked, probably due to over tightening as a result of the trapped o ring.
I managed to clean the EGR valve and refit it, I had to refit the throttle valve housing with the bad o ring and cracked body (can't get parts on a Sunday!), I will replace it this week. I took the car for a drive and had heavy power surges and erratic idling (Haynes tells me this is expected after unhooking the battery) but after around 10 miles I was still witnessing the surges at around 25000 rpm.
Do you think the trapped o ring is the source of my problems?
This car is only 4 years old so it's likely that o ring was trapped on original build, do you think I can get anything back from Renault on this one?
 

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Discussion Starter #5
Still having problems!!! Anyt ideas?

I've now replaced the throttle valve (or as Renault call it a connection piece?) and cleaned out the EGR valve, but the problem remains.

Any ideas what may be causing my surging at 2500 rpm and the black smoke?

Any suggestions would be greatly appreciated!
 

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A Slight Pluse at 2500 rpm

Hi,
I don`t know if this is going to help but here goes. I was getting the surging between 1500rpm and 2000rpm so I cleaned the EGR valve which wasn`t realy crapped up, but the two holes which join the egr chamber and the throttle damper chamber were. So I cleaned them out and everything seem OK except I noticed a surge at 2500rpm,I was only doing town driving, anyway this morning I changed the oil and oil filter and took the car for a good thrash. At the start of my blast the dreaded surge was there at 2500rpm. and as if something which had been lodged or blocked or crapped up went and the car now is running smooth as silk. Anyway I hope this might help?
 

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The bit you took off to get at the EGR valve is called the throttle stop valve and only activates when the engine is being stopped (it is vacuum operated and there is a vacuum resorvoir unit just down the back of the manifold) and should remain open at all other times. Firstly check all the small hoses going to the reservoir and the stop valve are properly connected and have no splits or cracks. When you had the EGR valve off did you check it was moving easily and springing closed on both flaps and also were the flaps tight on the spindle. It also worth checking the small hoses going to th eturbo are not loose or dgrade as there is quite a bit of heat at the back of the engine.:)
 

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Exactly the same problem

I have the same car with exact same fault, and the black smoke. It'covered 74,00 miles. The EGR valve is spotless. Renault say it could be a split intercooler. I think theres a leak in or around the throttle housing from a pipe maybe. Will have good look tomorrow. Its going into the dealer on Wednesday if I can't sort it by then. If they cure it I will post the result.
 

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If the intercooler splits it will cause engine oil to get sucked into the system and what appears to an oil leak will appear at the stop valve. Once this happens the engine starts to ingest some of the engine oil and actually begins to run on it as a source of fuel - thus the surging - with the injected fuel and the engine oil the fuel to air mix becomes to rich and will show as black smoke in the exhaust.:) Have a look through the link below and see if anything sounds familiar.

http://www.renaultforums.co.uk/engines/21240-hesitating-black-smoke-swollen-intercooler.html
 

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Discussion Starter #11
The link sounds very very familiar, i'll take a look at the intercooler in the next couple of days.

Let me know how you get on!

Thanks
 

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After doing a bit more research today it would appear that the EGR valve will fail to operate if one of the following is faulty. Coolant temp sensor. Air temp sensor. Atmospheric pressure sensor. Accelerator pedal position potentiometer. Engine speed sensor. Airflow meter. Injection Flow rate sensor. Turbo pressure sensor.
I had a new pedal whilst in France recently but it made no difference. Checked my intercooler but that seems fine. Definitely one for the dealers lap top until I get the diagnostic pack myself or change the car.
 

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Discussion Starter #13
The dealership plugged my 1.9 dCi into the diagnostics and found faults recorded with the glow plugs and Top Dead Centre sensor. They replaced these and charged me £500 without any improvement in the performance, the surge and smoke remained.
I assume if any of the other sensors you mention are bad then this would show up on the diagnostics, so i think they are good.
I think my next step is to check the intercooler.
 

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I don't have the surging but does oil spit out of your dipstick hole when it is removed, just wondering if you have high crankcase pressure like I have. Oil from the breather is getting fed back into the engine, I am sure it is a cracked inlet manifold/rocker cover that is wrong with my engine. Could account for power loss although mine is ok, depends on size of crack.
 

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Discussion Starter #15
The EGR valve op[ens about 5mm when pulled, it closes easily under the spring loading. The sealing faces are good so i presume the flaps close ok.
 

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I wonder if it is something simple.

When I cleaned my EGR valve and removed the throttle stop for access. I noticed the vacum line had been rubbing on the manifold and was wearing into a hole, so I wired it up to keep it away from the manifold. It`s worth a look you never know.
 

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Primarily surging is due to changes in fuel/air ratio. In other words the air and/or fuel rates are changing. A cracked manifold will give this affect as also will engine oil being ingested via a leaking intercooler or via a breather pipe. It is worth checking the inside of the main air inlet pipe which should be clean and dry - with no visible signs of contamination. The engine management system has no means of knowing if the intercooler is leaking. The intercooler has been modified with additional straps to prevent it swelling and cracking.:)
 

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Renault has confirmed that my intercooler is split, so thats the starting point. Hopefully thats all. They don't think there are any problems with the turbo because it's not making any noise. The cooler was split at the bottom near to the bottom hose fitting.
 

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Discussion Starter #20
I'n going to take a close look at my intercooler this week, I'm not sure what renault will charge but i've had a quote from europarts aat £134 + VAT.

Let us know if the intercooler solves the surging
 
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