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wefwef, Technical support engineer
Category: UK Car
Satisfied Customers: 305
Experience:  20 years experience,15 with Renault as master technician,technical support for 2 major manufacturers
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My sons renault megane dci y reg keeps loosing acceleration

Resolved Question:

My sons renault megane dci y reg keeps loosing acceleration when he puts full power on especially uphill and the engine management light comes on. he has been told the diagnostic can only find the fault if its happenning when it goes into the garage. help cannot afford to keep having tests with no result.
Submitted: 7 years ago.
Category: UK Car
Expert:  wefwef replied 7 years ago.
Hi, loss of power can be caused by numerous things and if you are driving along and the engine management light comes on there should be a memorised fault that can help with diagnostics. If not there are some areas that I would check first. I would ensure the air intake is fitted correctly and tight and all pipes are free from splits. I would check the wiring connectors and ensure the wiring near the connectors is not damaged as they can have a habit of the wiring breaking near the connectors....more common ones are the two pin connector on the pressure control valve located on the high pressure pump. Fuel pressure can give issue on modern diesels as they are very sensitive to dirt. I would advise changing the fuel filter and ensure the fuel is of very good quality and not supermarket diesel. I would remove the air intake pipe from the air filter to the turbo and check the turbo impellor for damage and the shaft for excessive sideways movement, as the turbo may be sticking or developing an issue. The mass air flow meter can give an issue, but a proper diagnostic would be required to diagnose with more certainty. If you are able to replicate the issue regularly, the best option is to show this to a good technician with good diagnostic equipment and they can then replicate the issue and monitor the parameters to diagnose better. The main starting point for diagnostics is to remove and inspect the EGR (exhaust gas recirculation) valve located on the front right hand side of the engine in the inlet manifold. It is held in with three 10mm bolts and pulls towards you. A connector with 6 cavities is connected to it and it has a round metal solenoid that you can see from outside of the engine, the valve part fits inside the manifold. You could diagnose this yourself by removing the valve completely and leave it connected electrically. Make a blanking plate for the hole in the manifold and see if the problem disappears. If it does I would advise replacement of the EGR valve and gasket. Renault have a tool that can check these valves for sticking etc, but if your problem is intermittant then the check can only be valid at the time of checking so may not pick up your issue. Sometimes the end disc from the valve falls off and gives problems on earlier vehicles, and also they can become blocked with carbon. It is well worth checking this as they do cause issues on all modern diesels, and the Megane is no exception. I hope this helps. Kind regards
Customer: replied 7 years ago.
Hi Sorry for slow communications but have limited access to the internet. Have found original fault codes didn't know if they would effect your answer. DF070- COHERENCE BETWEEN CAMSHAFT SENSOR / ENGINE SPEED and DF089 - INJECTOR CONTROL CONDENSER VOLTAGE Thanks
Expert:  wefwef replied 7 years ago.
Hi, the fault codes may be related to the problem but these kind of codes would normally result in non start or stalling/similar. The DF070 may be brought on by the engine speed sensor/cam sensor or their wiring respectively, but usually you would get non start as a symptom. DF089 is relating to an internal problem with the engine management computer and the condensor controlling the injector voltages. This may well indicate a problem in this area, but as this would be an expensive replacement I would suggest carrying out the basic checks above and also clear the fault code memory and then replicate the issue and see whether the codes return with the problem which could confirm that this particular code relates to the problem. I hope this helps. Kind regards
wefwef and 2 other UK Car Specialists are ready to help you
Customer: replied 7 years ago.
Cheers XXXXX XXXXX information will get him to start working through the list of things to check.