XSeries-forum

Hi,

So i noticed this morning on the way to work that when travelling at a constant speed (about 60 mph) on the motorway I was feeling a bit of hesitancy from the engine every so often in slow bursts. The problem doesn't seem to occur when on full throttle.

Anyone had this before?

Thanks

Pav

Assuming it's a diesel - Check your vacuum hoses are all on (that would affect the turbo boost). Other than air inlets/trunks etc, all I can think of is fuel delivery. Have you just refuelled and it started straight afterwards? After that it could get complicated as it might be injectors, pumps, partial air lock in the tank (is the cap OK and no blocked pipes?) causing a slow vacuum build-up in the fuel side which then breaks as more air gets in so fuel pressure comes back up.

If nothing obvious, and no one else can think of anything, you might need a code reading done to see if any flags are set.

Possibly MAF or EGR. Different cars give different symptoms when these fail though. I had a diesel Vectra that "surged" under full power when the MAF had gone. My Focus didn't do this though. It was just unresponsive until the MAF was changed - seemed OK until full power. Our Espace was sluggish when the EGR was faulty.