Xsara Picasso low power at slow speeds 2.0HDI

[goatie]

hi all, got an old Xsara Picasso 05 reg, 2.0 hdi, the EGR keeps coming up as a fault (P0400, P4001) spraying the cleaner in it does help, but the EML still comes up, only use the car for runs to the tip & picking up firewood etc so don't think I do more than 1500 miles a year
the bigger probelm i have is when at slow speeds or from stop there is a lack of power, then when I get to 40 mph or so it suddenly busts in to power and away it goes
someone suggested it could be the vacuum pipe to the turbo (where do I looks for this ? any way to check it ? is there a way to check with lexia ? )
any thoughts on what else it could be ?
now I'm an old man my brain (and my body) can't do or workout this stuff any more, but it doesn't stop me trying

[wheeler]

The Picasso 2.0 HDi only came in 90 bhp so there is not turbo eletrovalve with a vac pipe controlling it. The vac pipe is only a couple of inches long & is on the turbo itself, just need to check its not split or blocked. However I'd be looking at the EGR valve first, Might be worth blanking it off (for testing purposes) & see if it solves the problem. The thing is these EGR valves have no direct electronic feedback to the ECU so they dont normally throw up fault codes if they are not working correctly. If its throwing up EGR related codes It could also be an issue with the electrovalve that controls it or the MAF sensor.

[goatie]

thanks for info,
i can't get the EGR valve off as I've rounded one of the nuts, (taken the engine off the mounts and moved it forward but not enough room to get anything on rounded nut to loosen it ) changed the EGR about 8yrs ago this one has done about 40K miles, but most of that is 5-8 miles
I've changed the electrovalve (vacuum valve on side of engine bay) one hose goes to EGR the other hose goes ? (do you know where it goes ?)
not changed the MAF sensor, Yet
when it stops raining I'll try to get under the car and see if i can check the turbo vacuum pipe
just looked at MAF testing vid's anyone know what the volts should be at Idle and when reving up ?

[wheeler]

I've changed the electrovalve (vacuum valve on side of engine bay) one hose goes to EGR the other hose goes ? (do you know where it goes ?)

just looked at MAF testing vid's anyone know what the volts should be at Idle and when reving up ?

The other end goes to the vacuum pump.
What air flow reading are you getting with engine warm & idling with both the EGR vac pipe plugged in then disconnected?

[goatie]

tested MAF sensor
EGR vac pipe on Idle 1.1 volts 2500/3000rpm 2.1 volts
EGR vac pipe off Idle 1.1 volts 2500/3000rpm 2.1volts

volts appear rise/fall evenly

[wheeler]

The MAF should measure in mg per stroke or mg/cp not volts.

[goatie]

i was just testing as per the vid's
I maybe able to see the live data via Lexia or Delphi , but not sure what it should be

[wheeler]

Yes you need to read live data. With engine warmed up & idling the air flow reading should be around 220-280 mg/cp if you then disconnect the vac pipe off the EGR valve you should see the reading jump up to around 500 mg/cp.

[goatie]

I'll try to do the live data tomorrow thanks
going back to the EGR and the Vacuum pump where is the vacuum pump ?
if I take vacuum hoses off the EGR electrovalve should i feel a vacuum ?
the electrovalve for the EGR is the electric side powering the valve or is it signal back to ECU ?

[wheeler]

I'll try to do the live data tomorrow thanks
going back to the EGR and the Vacuum pump where is the vacuum pump ?

On the gearbox end of engine driven by the camshaft (circled in yellow)

if I take vacuum hoses off the EGR electrovalve should i feel a vacuum ?

Yes, with the engine running you should, be sure not to mix the pipes round the wrong way as its important they are fitted on the correct port.

the electrovalve for the EGR is the electric side powering the valve or is it signal back to ECU ?

The electrovalve is always powered with 12v when the engine is on & the ECU controls how much it opens by earthing it with OCR control.

[goatie]

Thanks for that
managed to find a picasso engine data fie here is the EGR circuit for my Pic
not sure if there is a way to upoad the whole file to the site ?

[goatie]

Just checked using Lexia & delphi
Lexia Dephi about 30 mins later
Idle 730 RPM Mass air 170 mg/cp Idle 788 RPM Mass air 4.49 g/s
2700 RPM Mass air 300 mg/cp 2700 RPM Mass air 300 g/s

when I took the vacuum tube off the EGR valve the figures were the same as above

[wheeler]

If your MAF sensor is reading correctly i’d say your EGR valve may be stuck open. Both the idle & 2700 rpm readings are way to low, especially the higher RPM, id expect to see at least double what you are getting on that one.

[goatie]

could it be a clogged air filter ?
readings should be

Lexia
Idle 730 RPM Mass air 170 mg/cp 2700 RPM Mass air 300 mg/cp

Delphi
Idle 788 RPM Mass air 4.49 g/s 2700 RPM Mass air 300 g/s

[wheeler]

could it be a clogged air filter ?

Highly unlikely but you could rule it out by just removing it to read the live data.

If at idle speed you are getting lower than 500 mg/cp with the EGR valve vac pipe disconnected and then either:-
1) The EGR valve is not fully closing.
2) You have an air leak after the MAF sensor.
3) There is a restriction in the airflow (including also the exhaust), Remember there is a vacuum operated butterfly in the intake.