Xantia HDi smoking

HDI · Post by **HDI** » 24 Jan 2011, 20:17

No wonder it flies !!! I wonder if the map sensor is reading correctly though ?
Even if it is the ECU should go into limp home as a result of overboosting.

DickieG · Post by **DickieG** » 24 Jan 2011, 20:17

When I get the chance I'll connect up my Lexia, go for a drive and compare readings.

Post by **DHallworth** » 24 Jan 2011, 20:19

Don't worry to much DickieG,

I'll plug it into our SX tomorrow and compare it with that.

Paul's told me that the boost sensor is on top of the intercooler so I'll have a look at that tomorrow too.

Does anyone know if leaving those metal plates I fabricated across the EGR will cause any damage?

Ta!

David.

HDI · Post by **HDI** » 24 Jan 2011, 20:21

No, they won't. EGR is just for emissions.

Post by **DHallworth** » 24 Jan 2011, 20:22

HDI wrote:No, they won't. EGR is just for emissions.

Thank god for that!

I think I'd scream if I had to take them out! My hands are sore and covered in scratches after fitting them!

If anyone wants me to fabricate a couple more then let me know.

David.

dieselnutjob · Post by **dieselnutjob** » 24 Jan 2011, 20:41

I think it means 2 bar absolute pressure
In other words 1 bar of atmospheric pressure and 1 bar of boost
1+1=2
which is as it should be
Does it still smoke with the EGR blanked off?
By the way just leave it blanked forever. It's better for the engine to not be breathing in carbon particles as they are slightly abrasive.

Post by **RichardW** » 24 Jan 2011, 20:42

Those pressures may well be absolute (ie atmospheric pressure plus the bit on top) - hence 2 bar is about right.

dieselnutjob · Post by **dieselnutjob** » 24 Jan 2011, 20:49

DHallworth wrote: Turbo Pressure Measured: 2014 millibar
Turbo Pressure Setting: ~2000 millibar

the clue is here.
the ECU is trying to set the turbo to 2000mbar absolute. It is actually getting 2014mbar.
So it it overboosting by only 14mbar. i.e. the ECU is getting 14mbar more than it wanted.
14mbar is basically nothing, so the ECU is happy.

If the ECU sees a big overboost it will put the warning light on and limit the engine to 3000rpm to try and protect the turbo. Happened to me once when a vacuum pipe fell off and the ECU lost control of the turbo.

Post by **DHallworth** » 24 Jan 2011, 20:58

Does the fact that it's running at 2 bar rather then 1 bar have any significance at all or am I just being thick again?

David.

dieselnutjob · Post by **dieselnutjob** » 24 Jan 2011, 21:06

2 bar absolute is 1 bar above atmospheric pressure so it's perfect.

Measure it with the engine not running or idling and it should say 1 bar.

The only way you'd ever see zero is in a complete vacuum, which ain't happening.

Post by **DHallworth** » 24 Jan 2011, 21:18

Of course, that all makes sense now.

This gets more puzzling though.

As suggested, if the timing was out there would be fault codes registered.
The EGR can't be causing it as it's doing the same with it blanked off.
The boost pressure is spot on.
The car doesn't use a drop of oil.

I'll try and check the compression tomorrow as also suggested by Dieselnutjob and will compare that to the compression on the SX.

When starting the car in the morning when it's cold it occasionally catches on 3 cylinders, when revved gently though it always takes on the 4th. I only noticed this when it was very cold though.

David.

dieselnutjob · Post by **dieselnutjob** » 24 Jan 2011, 21:42

DHallworth wrote:When starting the car in the morning when it's cold it occasionally catches on 3 cylinders, when revved gently though it always takes on the 4th.

I'm afraid that's not right. Could be a stuck hydraulic tappet as easily as rings though, or even a glowplug I suppose, but that would only affect it when it first starts.

Post by **DHallworth** » 24 Jan 2011, 21:49

It only does it when it first starts.

As soon as it's been running for a second or two it runs on all 4 normally.

I'll try and get a video of it cold starting tomorrow.

It was that which led me to replace the glow plugs and the glow plug control box.

No matter how cold it is the light flashes on for 1 second then goes off. In the really really cold weather it was taking several wacks of the glow plugs before we even attempted to start it.

David.

HDI · Post by **HDI** » 24 Jan 2011, 21:51

dieselnutjob wrote:I think it means 2 bar absolute pressure
In other words 1 bar of atmospheric pressure and 1 bar of boost
1+1=2
which is as it should be
Does it still smoke with the EGR blanked off?
By the way just leave it blanked forever. It's better for the engine to not be breathing in carbon particles as they are slightly abrasive.

Oooop's, I was thinking boost gauge reading !

HDI · Post by **HDI** » 24 Jan 2011, 21:54

DHallworth wrote:It only does it when it first starts.

As soon as it's been running for a second or two it runs on all 4 normally.

I'll try and get a video of it cold starting tomorrow.

It was that which led me to replace the glow plugs and the glow plug control box.

No matter how cold it is the light flashes on for 1 second then goes off. In the really really cold weather it was taking several wacks of the glow plugs before we even attempted to start it.

David.

Definitely not typical of an HDi, the colder it is the longer the glow light stays on and even on the coldest day in December mine fired first turn and ran on all 4. There is a clue to something not being right here.