l have a problem with a renault grand scenic 1500 dci 2005 model with just over 12k on clock.The problem is when driving up hill or with accerlerator pedal to floor for 20 seconds the injection warning light is on but after easing of for 2 minits it go is off???.l have noticed air returning from disel pump but not going to pump down fuel line aslo when warning light is on black smoke streams out the exhaust but not being used out of engine...This car was accident damaged and cannot go into dealers as part of a court case the case is to be heard feb 2007 and l do not whant to cause any more damage AS ANY ONE AN IDEA TO PROBLEM

really hard to pin point without having the car in front of me but these models have a E.G.R valve..exhaust gas recirculation valve which l have seen in some cases to stick closed or remain open at the wrong time causing all sorts off problems along the lines of what u described..when working it dumps excesses exhaust gas back into the engine during normal acceleration at speed thus reducing emissions as its burnt twice..it would seem the likely suspect but its not an easy diy job..its def a garage job..should not do much harm but if it gets worse u will start loosing power & the car may even go into a limp home made which could be dangerous on a motorway!