Hi all,

i have a 2010 focus 1.6 hdi done just over 70k, its started to hesitate around 1400 rpm if I put my foot down it picks up ok but if I hold the revs at 1400 that’s when it stutters. No fault codes are present. I disconnected the maf and the issue goes away, as soon as I plug the maf back in it happens. I replaced the maf with my friends (same car and no issues and it’s still doing it. Any ideas?

thanks in advance

4 hours ago, Carmadkevin said:

if I put my foot down it picks up ok but if I hold the revs at 1400 that’s when it stutters. No fault codes are present. I disconnected the maf and the issue goes away, as soon as I plug the maf back in it happens.

EGR valve is one possible. This valve is only in use under light to moderate load. When you put your foot down, the car needs max oxygen, so the EGR closes. The MAF is used to control the amount of EGR, so if removed, the ECU detects this, raises an error code I assume, uses some default air flow strategy, and must close the EGR valve as it cannot compute the flow.

Other possibles are turbo actuator or vacuum solenoid, or, worst case, injectors. But I think I would start by checking, or just blanking, the EGR.

Blanking is fine for a diagnostic test. It could affect engine efficiency and emissions if left blanked, but usually is not a huge problem. MoT test does now look for visible changes to the emission control system, so a visible blanking plate could be a fail.