2009 1.6 tdci hiccups

[211v2a3]

I'm starting to think this car was a friday afternoon job but hopefully someone can help solve this latest issue.

The car has started to hiccup occasionally when cruising ie when the throttle isnt pressed that much.  If i put my foot down, the car responds and seems fine but its just at that steady speed it doesnt seem to like.  Ive checked and cleaned both the MAF and EGR but tbh, at 47k miles they both seemed pretty clean.

Any ideas?

As always, massive thanks in advance.

 

PS, now that i work at Sainsburys, i was wondering if the constant supermarket diesel was having a detrimental effect?

 

[Paulkp]

Just a guess, as I am not familiar with diesels, but if related to throttle opening for a steady speed then I might suspect the throttle/accelerator position potentiometer has worn at that point.

I had this on a petrol car a long time ago.

[211v2a3]

Apologies for the delay in replying.  Chrome wouldnt open the webpage for some reason until i deleted all the cookies....

Anyway, done a few more experiments and it seems that it happens when the throttle is either closed (or very nearly) which says to me that theres either too much air getting in the system (high vacuum) or not enough fuel.  Not only does it happen on steady small throttle driving, it also occurs on decelerating ie throttle closed with resultant hesitant pick up afterwards.

A bit of digging around with similar symptoms brings all manner of suggestions from split hoses to knackered EGR.  Sensor issues including the TPS and cam shaft also pop up.  Looks like this is going to be a right doozy to fix.

 So I cleared all the DTC's (i recently had an alternator failure), changed the MAF then went for a drive.  Same thing but no DTC's.  Best suggestion so far speaking to someone on this forum is a dodgy injector.  

Anybody have similar experience? ideas?

 

[Tizer]

An Injector or Fuel problem is the most likely cause, but it could be a lot of other things.

Diesel engines usually have a Throttle Plate, sometimes two but they do a completely different thing to the one on a Petrol engine, they are almost fully open nearly all the time and do not close off the air supply at light Accelerator openings. There is no direct link to the Accelerator Pedal.

The Electronic Accelerator Pedal in monitored to within an inch of its life for safety reasons and if there was a fault I would expect a Fault Code to pop up. They usually have two or three tracks that work either opposite to each other or on different slopes and if they do not correlate with each other a Fault Code is normally set.

A split hose would normally show a drivability problem at higher loads when the Turbo is working harder rather than lower loads.

A restriction in the Airflow would show up as a negative (i.e. below 100kPa) MAP reading. 

[211v2a3]

19 hours ago, Tizer said:

An Injector or Fuel problem is the most likely cause, but it could be a lot of other things.

Thanks.  Im trying to get the urge to remove the injectors (i have new seals anyway) just hoping none of them are going to be stuck.

But, a lot of other things?  Name your top five!