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[Scatmancraig]

It's been a few weeks of relatively trouble free motoring for me, but a new fault is starting to rear its ugly head.

The car is a PFL 2.5 TD auto.  Just lately, it is starting to stall when selecting either drive or reverse.  It is worse when cold, but it does it when fully warmed up too.  Usually much worse when selecting gear with my foot on the brake pedal and a touch of steering lock on at the same time.  Once it's in gear, it is usually fine, although when braking to a complete standstill, you can feel the engine surge slightly when almost stationary, as if the engine knows its about to stall and compensates. 

Not sure if this is connected or is the cause of the problem, but I've noticed that when I start the car from cold, the engine fast idles until I press the brake pedal.  Then there is a noticeable reduction in engine revs.  It's almost the same when running with the engine warmed up, if you press the brake pedal whilst ticking over, you can hear the engine falter slightly. 

I usually get around the problem by making sure I'm parked somewhere that doesn't involve a three-point turn, and where I can select a gear without using the brake pedal at the same time.  The village Co-op is favourite as its very tight for parking. 

Any ideas what might be causing this?  The continued help of this forum is always much appreciated! 

[Shackeng]

Sounds like a vac leak somewhere if pressing the brake causes rev alterations. 

[Scatmancraig]

Sounds like a vac leak somewhere if pressing the brake causes rev alterations. 

Yes I thought that, but where?  Are there any usual culprits for vac leaks?

[tigers_gonads]

Just follow the pipes from the brake servo to the pump Craig.
A blast of brake cleaner around and joints while listening for a rise in revs may also help 

[Scatmancraig]

After investigating the brake pipes, I'm still no further forwards with this, and the problem is getting worse.

Now the car has developed a habit of cutting out when going coasting round a corner at low speed.  My foot isn't on the throttle or the brake, but it seems like turning the steering wheel can have an effect on the engines ability to run.  By the looks of things, anything that puts a load on the engine when it is idling (i.e. putting it into drive or reverse, steering or braking) sets it off and the engine becomes erratic.  Three point turns or getting in and out of tight parking spaces are the worst.  Usually it recovers its composure fairly quickly, but often cuts out.  If this was an old straight six petrol, i'd be heading straight to the idle valve and cleaning it, as the symptoms are similar.

Are there any common reasons for the 2.5 TD to develop a stalling habit?  It only ever happens when the engine is at idling speed, never when any throttle is applied.  But I've no idea how the idle is controlled on these cars.

[Marks DTM Calib]

It wont be vac on a diesel.

To me its fuelling, are the leak off pipes all ok?, is the fuel filter ok? EGR good and clean or blanked off?

[Shackeng]

There is a vac pipe from the underside centre of the inlet fanimold that goes to a gizmo close to the front of the pax
bulkhead, on mine the anti-theft bonnet microswitch is adjacent to it. Check that the pipe is not leaking, they sometimes crack if ancient, is fitted properly, and is also clear. (blow through) 

[Scatmancraig]

It wont be vac on a diesel.

To me its fuelling, are the leak off pipes all ok?, is the fuel filter ok? EGR good and clean or blanked off?

The EGR valve is still fitted, but the vacuum pipe to it has been blanked off by a previous owner.  I was considering getting a blanking kit as they seem cheap enough and easy to get hold of. 

I'll check the leak off pipes when I actually get some daylight hours to see what I'm doing.  I haven't noticed diesel leaking before, nor can I smell it, but then again I haven't really been under the bonnet at all since I replaced the auxiliary belt tensioner a few weeks ago.

There is a vac pipe from the underside centre of the inlet fanimold that goes to a gizmo close to the front of the pax
bulkhead, on mine the anti-theft bonnet microswitch is adjacent to it. Check that the pipe is not leaking, they sometimes crack if ancient, is fitted properly, and is also clear. (blow through) 

Good shout, I think I know which one you mean.  Another thing to check in the daylight!

[Scatmancraig]

Managed to do a few basic checks the other day.  No signs of leakage around the leak-off pipes, all the injector recesses are dry and the pipes themselves seem ok.  There was a slight weep from the fuel filter, so I tightened it up a little.  Took it for a drive, no difference.

I can be sat in stationary traffic with my foot on the brake, and it will idle in gear ok for so long, then every so often the engine tries to cut out, but recovers itself causing a fairly noticeable surge in the engine revs.  This doesn't seem to happen if I sit in traffic (in gear) with the handbrake on instead of the footbrake.  So maybe the problem is vacuum related after all?   Or is the engine idle too low, as the problem only every occurs with no throttle applied.  Sometimes the engine hunts a bit when idling, especially from cold, but when warm it is ok, and it pulls like a train otherwise. 

I'm a bit mystified with this one!!

[Shackeng]

Managed to do a few basic checks the other day.  No signs of leakage around the leak-off pipes, all the injector recesses are dry and the pipes themselves seem ok.  There was a slight weep from the fuel filter, so I tightened it up a little.  Took it for a drive, no difference.

I can be sat in stationary traffic with my foot on the brake, and it will idle in gear ok for so long, then every so often the engine tries to cut out, but recovers itself causing a fairly noticeable surge in the engine revs.  This doesn't seem to happen if I sit in traffic (in gear) with the handbrake on instead of the footbrake.  So maybe the problem is vacuum related after all?   Or is the engine idle too low, as the problem only every occurs with no throttle applied.  Sometimes the engine hunts a bit when idling, especially from cold, but when warm it is ok, and it pulls like a train otherwise. 

I'm a bit mystified with this one!!

Did you pull the pipe I mentioned off and check it is clear?

[Scatmancraig]

Did you pull the pipe I mentioned off and check it is clear?

I checked both ends of the pipe for condition, the manifold end was a bit worn, so I removed it and cut the frayed end off the pipe and reattached it.  I didn't blow through the pipe, so will remove it again and do that later.