2.2dti Engine hunting??

**Marshal** · 19th March 2010, 17:34

Hi folks, I'm getting very frustrated trying to sort out this problem with my signum. The engine revs fluctuate up and down when I do short journeys, on long runs its ok but every now and then the engine will miss a beat for a split second. I've changed the AFM and the EGR and all seemed well until a short journey today then the engine began hunting again, if I disconnect the AFM engine runs fine, does anyone have any ideas?
If it's the fuel pump its gonna cost £2300 to replace I'm praying its something cheaper and easier to replace.
Oh by the way my Signum is a 04 with 133k on the clock, motor way miles, well serviced and maintained, I'm not getting any diagnostic codes when the spanner light comes on either.
Any help would be appreciated.

**chris1804** · 19th March 2010, 21:27

what ive been told about the pump is when it goes it goes instantly, so i wouldnt say pump

**eaglepva** · 20th March 2010, 10:48

my signum does this 2. When it done it yesterday i pulled a vacume hose of the butterfly flap, (above the EGR valve) and its run fine since so im gussing i need a new throttle body/elobau sensor. if i put the vacume hose back when on the motorway i get the slight misfire, pull it back off and its fine. the vacume hose controles the flap that is in the throttle body.

**david.aka.judas** · 20th March 2010, 11:12

have you checked for split pipes?

**Daywalker** · 20th March 2010, 12:10

somewhere you have a leak letting more air in hence engine is hunting on idle.

**Marshal** · 20th March 2010, 13:33

Cheers folks, I'm going to pull the vacum pipe off the butterfly flap to see if it makes a difference. I've checked all the other pipes and all seem fine.
Thanks for the help I'll keep you posted.

**Marshal** · 20th March 2010, 13:52

Its the throttle body! Can I run it without the vacum pipe connected or will it cause problems elsewhere? How can I solve the problem or do I need a new throttle body?

**david.aka.judas** · 22nd March 2010, 18:51

I would speak to the workshop foreman @ vx.

**Marshal** · 1st April 2010, 18:52

The nightmare continues!!
I took car into VX stealers for there diagnosis, they said it was the overboost sensor, they couldn't get one for 2 days so they gave me my car back, it was running worse than ever after they'd had there hands on it. Anyway, I collected it today with new sensor fitted and guess what, I drove 2 miles put my foot down and it went straight into limp mode. Diagnostic reading is turbo overboost again.
It's costing a fortune plus causing me to stress out everytime I take my car out.
I have no idea where to start looking now to solve this problem, have any of you guys got any ideas?