Pulsing engine when cold

[LukeClark]

Hi guys, 

I new to this and I’m after some advice... I have a Peugeot Partner (is that sacrilege on a Berlingo forum) ??.
1.6hdi 2009 but still the M59 as it’s the Multispace version.

I’ve had an issue since i bought it about a month ago. Particularly when the engine is cold. The engine seems to pulsate. Not when accelerating but when either at idle or keeping constant revs going up to about 30mph. 

I’ve just done a full service on it, it’s definitely running smoother but the pulsating is still there...and have no eml on.

Any ideas as to what might be causing it? Appreciate your help!

[Sol]

First thought would be oscillation in the fuel pressure or the airflow (fuel pressure regulator, MAF or EGR throttle as it's active when idling)

Hard to be exact, but if you had DiagBox or knew someone who does then you could read live fuel pressure at idle along with airflow and EGR throttle value (there's a butterfly plate in the doser unit that regulates the intake between EGR gases and fresh air, also bypasses the intercooler during warm up)

Finally you might have a clogged injector or one that is otherwise faulty, so when it is in low output (idle or steady cruise) it's pulsing.

[LukeClark]

Thanks Zion,

I thought it may have been the EGR but I took some of it apart and it wasn’t too bad, I think you might be right about Fuel pressure regulator. I’ve ordered a Diag tool so will try and read the fuel pressure and EGR throttle value. Any idea what they should be at idle? 

Also is the fuel pressure regulator easy to replace? If so where on the engine is it? Heard it was quite simple. I’m not super skilled but enjoy minor works. Thanks again ????

[Sol]

Fuel pressure at idle is 290-300 bar on the HDi, and airflow at idle is 395-420 units at idle with the MAF working, 400 solid with it disconnected before starting (from the default AF map)

The question of the FPR location is a good one, on 1.6 HDi, its a bit of a nightmare - it's always plugged into the end of the HP rail on the HDi's which is behind the engine on the 1.6, round a corner behind a bracket under a pipe....you get the idea. I reckon it's a good 2 or 3 hours work to change it and you have to remember the rail is always pressurised so to get it off (without looking at the Haynes) you would have to be able to depressurise the rail safely - either by pulling the fuel pump fuse and starting it so the rail gets used up naturally...or gently loosen one of the injector steel hard-lines nuts slightly until fuel seeps out, then leave it for a while until the pressure has gone. Mind your eyes, wear safety glasses and gloves, keep hands and body away from the hard-line while cracking it open with a longish spanner and cover the area with a cloth before cracking the nut open. Don't run the HDi with a hard-line open, there is a risk of high pressure injection injury.

The idle and static pressure of the rail @ 300 bar is 4,320 PSI....

It will be sitting at 300 bar which is a lot of pressure when you shut it down. The battery and battery tray has to be removed, one of the bolts is hidden in the arch behind the liner, then behind the engine there is a pipe and a bracket that cover up the sender unit itself - it is screwed into the end of the fuel rail pointing along the engine towards the battery area.

I'll attach the BlueSpark tuning box install instructions as they are a good guide for getting at the FPR on the 1.6 HDi.

The EGR itself, should only really be open or closed, but the reason it can cause airflow issues is dur to being open when it shouldn't be, or closed when it should be, or stuck some way between. Also when the ECU wants to use EGR at idle, on the over-run or even steady throttle cruising, it opens a diverter flap in the doser assembly (called EGR Throttle) and it can cause issues if the doser flaps are gummed up or otherwise faulty, the Doser is the black thing with 2 large bore tubes between the intercooler and intake.

[LukeClark]

Many thanks for the in-depth help! I might be a bit out of my league that ? But hopefully the diag tool will help too. I’ll post some figures on here once I’ve tested it and perhaps it might reveal more and I can kindly ask for your input. Thanks again!!

[Sol]

No worries! If you get a diagnostic handheld, it needs to be able to read live data. You might be lucky with a Bluetooth OBD plug (ELM327 fully compatible) and the Torque Pro app from the play store, it's about £3 and the OBD ELM327 adaptors are about £20...there are some really expensive ones but they are no better really. Some cheap ones will not support the full ELM code set and it's hard to tell with the Chinese eBay stuff before you buy.

The Carista adaptor is really good, and it works with Torque Pro (I have one) and it's about £25.

[LukeClark]

    Ok so I’ve just plugged it in and these are readings I’ve got including the fault codes. I’m guessing I should take all the EGR apart and clean it properly. Worth a try before buying new??

Maybe you could take a look at the live readings for me?

As for the glow plug fault I can’t work that out as it starts on the button every time so not sure what the fault could be? And the CPP... is that worth doing?

Many thanks mate!

[LukeClark]

    Sorry they went out of order a bit... I also have this reading...

[LukeClark]

Hopefully that’s enough. I used car scanner but if I should use the app you suggested I’m happy to?

[Sol]

Ok so 25760 kPa = 257 Bar so that's ok if a wee bit low (must be idle?) Is it steady at that value?

Excess airflow from the EGR looks like the EGR is sticking open, not shutting properly due to crud (usually thick black deposits of sticky soot) stopping it rotating to the closed position but at idle it should be open anyway....maybe the doser valve is actually stuck or faulty. EGR throttle - might not be able to read that with a generic reader.

13mg airflow seems very low. Should be 400mg at idle. That could be why the fuel pressure is at bare minimum. Try disconnecting the MAF when the engine and ignition are off, start it, and measure these tags again, see if the airflow goes up to 400mg and fuel pressure rises to 300 bar (30,000 kPa)

The EGR can cause airflow errors though.

I'd clean it thoroughly but try the test I suggested first, and see if the readings come up to the normal values. You will get an error for MAF but it will go away when it's reconnected.