no power below 2500rpm, but the power comes back when it's over 2500rpm. EGR is already cleaned and closed. help pleaseeeee

Try running with the MAF disconnected for a short while & see if power returns to how it should be.

Ffoxy said:

Try running with the MAF disconnected for a short while & see if power returns to how it should be.

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thx for quick reply. i've tried that too. it's going little better but it's making black smoke. I'dont think it's MAF. after 2500rpm the car has full power. i think something with turbo. how can u check the turbo?

Cant help with turbo testing sorry, but you do have a clean air filter I assume? Check pipework to & from the turbo before looking at a turbo issue, contrary to popular belief turbochargers are normally very reliable if kept serviced properly & not abused.

midayt47 said:

no power below 2500rpm, but the power comes back when it's over 2500rpm. EGR is already cleaned and closed. help pleaseeeee

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This is classic EGR failure symptom - black smoke (unburnt fuel) loss of power below 2500 (operating range of EGR).

Try a blanking plate on the inlet manifold end and tell me it's still behaving badly!

Peat

Peat said:

This is classic EGR failure symptom - black smoke (unburnt fuel) loss of power below 2500 (operating range of EGR).

Try a blanking plate on the inlet manifold end and tell me it's still behaving badly!

Peat

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I'm pretty sure that the OP has blocked the EGR off :-
"EGR is already cleaned and closed. "

I have a Renault Megane 1.9 dci, with the exact same problem. No power at all below 2500 rpm. However, in second gear it seems to be gaining power at around 2000, from third gear onward I can feel the torque from around 1500. Also, when I'm trying to shift, the car jerks for a second or so before taking off. It's like it's not letting the gas pedal send the message to the ECU. What's weird is, the car is equipped with a particulate filter; regenerated it once and the car ran excellent for around 150 kilometers, no jerking, nice, smooth acceleration, then it came back to the normal state. I've now removed the particulate filter and again, the car ran nice for around the same amount of kilometers, but this time the jerking at shifting didn't disappear. It's really strange though, a particulate filter problem should put the engine in limp mode and not let it accelerate higher than 2000 rpm or so. Many people I've asked pointed to the EGR valve, which has already been cleaned twice. The valve is equipped with a position actuator which tells the ECU whether the valve is opened or closed. So blocking the valve off may not be effective if the actuator is broken and sends the wrong information to the ECU?

Just had a similar problem via a different route and after looking at all the forum write ups here decided to do the following;
Fault on the dash showed the overpressure boost valve to be guilty.So I cleaned the MAP and removed the convulated pipe cleaned that and replaced it blanking of the ends.Actuator was moving freely but did not check the boost sensor attached by the red pipe to the actuator.
We cleared the fault codes with Alfadiag and the dash control centre was clear. Took the car for a short run and everything seemed fine.Took the revs over 3500 and immediately the engine lost its perkyness and no acceleration. So I then removed the sensor I talked about and cleaned the small filter taking great care not to damage the gauze.It didn,t look particularily dirty, however, reassembled and went for a test run , because the car is not insured yet it was only a short one down and up a farm track.Gave the car some good revs and it seemed a whole lot better more guts and eager, came to a rest and noticed the management light had cancelled itself so this proved to me I had down something right so time will tell on the open road , hope this helps.

check the thin vacuum pipe from the turbo to what i believe is the dump valve, get the air intake bit off the front and look down you should be able to see it, its not a big job to fix/replace if its perished/split. if you can hear the turbo spinning up properly and issueing its pshteww whistle then the turbos a spinning fine n dandy.