My FORD FOCUS 1.6 Zetec 02 has failed the MOT because a hi idle test could not be carried out for emissions. Over 2,000 revs it starts to jump around, then will shoot to 3,000 revs. I have changed the engine management air valve but this has made no difference. The diagnostics are not registering a fault, anyone got a clue what this could be? Thanks

 

Had to take it to a ford dealership who tested everything without a positive outcome, but thought it was possibly an air leak in the manifold. I think its too expensive to have it changed bearing in mind that it may not solve the problem. Already shelved out Ł70 for the air valve, and Ł80 for Ford to tell me they don't really know what the problem is.

 

Could be a number of things mate. What springs to mind is possibly the TPS or perhaps your coilpack but these should've been spotted by diagnostics equipment.

 

Unplug the MAF and see if it still does it.