Renault trafic 2006 100dci doesn't run properly from cold?

As you have had the air flow sensor replaced it probably is not that again - was it a new part or second hand? if is was new it should have a warranty (renault warranty parts for 1 year /12000 miles) if second hand you probably have no warranty. The most likely faults are either a glow plug open circuit - which can cause all manor of bad running faults or the most likely fault is the injectors. These are electric as they are on most vehicles these days and do fail for a variety of reasons. Poor fuel (supermarket?), dirty connectors are the most common. They cannot be cleaned or reconditioned effectively and therfore need replacing with new. They are EXPENSIVE - £250 EACH + Vat + fitting
Try a couple of cans of injector cleaner first and a fast run up the motorway. If no better replacement is needed. I would suggest your renault dealer does it as its not an easy job. Be prepared for the dealer to come back to you to say he cant get the injectors out of the head because they have seised in (due to a corrosion issue between the steel of the injector and the alloy of the head), this is very common. The only way out then is:- replace head with new £2000 plus or take the head to a specialist and have the injector pressed or spark erroded out. Replace ALL THE INJECTORS and the glow plugs as a matter of course (keep the good ones as spares).
Whilst apart check for air leaks on the inlet manifold and air leaks on the boost side of the turbo.
Good luck.
PS this is not just a renault/gm/nissan problem, I have seen the same issues on transits, mercs and psa products. Over all the Trafic is a good van, as good as most and better than some!

martin.racer2
December 2009