C5 2.0 Hdi - No Power until 3500-4000rpm then whoosh....

Taqman · Post by **Taqman** » 02 Nov 2009, 11:25

Hi All,

I have this problem with my C5 2.0 HDi est (LX 03reg)

Generally pootling around town or cruising on light throttle it is fine, but just recently if you want to accellerate - Ha - not a chance..... it can be damn dangerous trying to pull out I found.....

The pedal goes down to the mat and nothing happens - the revs slowly build untill 3.5-4K then whoosh in comes the power and off it goes.

I recently had to replace the high pressure pump (leaking) so replaced the cambelt, water pump etc as well (it was due 88000 on clock), and it was running well after this,

You can hear the turbo whistle if revved gently when parked, but it is quiet not loud (sounds normal to me)

I've searched around and the suspects would seem to be -

MAF sensor (this did start after some driving in heavy rain - and a check inside the air filter showed moisture had got sucked in - there was little puddles in the grooves of the bellows section and the air filter has evidence of getting wet.)

Or problem with the turbo/egr/wastegate/overboost.

Anyone had similar problems and can offer suggestions?

Thanks in advance

Simon

HDI · Post by **HDI** » 02 Nov 2009, 11:49

My Xantia has this problem , combined with going into limp home in some circumstances. Replacing the MAF didn't cure it. I've been advised it's the boost control solenoid , or , electro valve in Citroen speak.

uncle buck · Post by **uncle buck** » 02 Nov 2009, 13:19

If I'm thinking about the correct part doesn't the boost control solenoid have 2 vacuum pipes going to it....can you not just link these pipes to test if it is the solenoid at fault?

Cheers.

HDI · Post by **HDI** » 02 Nov 2009, 13:23

You can , but then it will overboost and go limp home anyway.

uncle buck · Post by **uncle buck** » 02 Nov 2009, 14:11

Ah I see...

if it's anything like the set up on the Renault's it will have the boost control solenoid & that is controlled by the Turbo pressure regulator...this is mounted in the pipe that comes from the intercooler to the inlet manifold.
Some Renault owners have had problems with broken wires in or beside the plug that connects to the Turbo pressure regulator....with symptoms like you describe.

Cheers.

HDI · Post by **HDI** » 02 Nov 2009, 14:28

ECU controls the boost control solenoid which controls the waste gate actuator on the turbo.

uncle buck · Post by **uncle buck** » 02 Nov 2009, 14:46

So it doesn't have a Turbo pressure regulator?

HDI · Post by **HDI** » 02 Nov 2009, 15:46

The pressure is regulated by the wastegate.

boristhespie · Post by **boristhespie** » 02 Nov 2009, 16:11

HAd exactly same proble. Car had zero power until it hit 2000 and then took off. Then (this is probably not related) flooding came, went through a few ponds (Same last night jeeezz) and the car remedied itself. But the engine management light cam on instead. HAve had it to garage on computer, intermittent fault with egr and MAF but was advised too vague to go routing about.

But when no power it's helluva frustrating. And dangerous to overtake.

uncle buck · Post by **uncle buck** » 02 Nov 2009, 17:46

HDI wrote:The pressure is regulated by the wastegate.

Yes, but the waste gate is controlled by the boost control solenoid, this gets its signal to open or close from the Turbo pressure regulator sensor...yes the ECU acts as the middle man in this set up but none the less the Turbo pressure regulator sensor is in fact controlling the boost control solenoid.

I believe that the Turbo pressure regulator sensor is mounted at the front of the car where the pipe comes out of the inter-cooler on the 110 HDI engine.

Cheers.

HDI · Post by **HDI** » 02 Nov 2009, 19:01

Not really , the sensor just provides the manifold pressure signal to the ECU. The ECU controls boost via the solenoid and wastegate.

uncle buck · Post by **uncle buck** » 02 Nov 2009, 19:39

HDI wrote:Not really , the sensor just provides the manifold pressure signal to the ECU. The ECU controls boost via the solenoid and wastegate.

Are you being pedantic on purpose.....That's what I said above.

uncle buck wrote:...yes the ECU acts as the middle man in this set up but none the less the Turbo pressure regulator sensor is in fact controlling the boost control solenoid...

I'm just trying to figure out if the HDI engine is controlled in a similar way to the Renault engine & to see if I can help advise, as it sound like Taqman's problem & indeed yours could be down to the either of these components.

Cheers.

wheeler · Post by **wheeler** » 02 Nov 2009, 23:28

uncle buck wrote:If I'm thinking about the correct part doesn't the boost control solenoid have 2 vacuum pipes going to it....can you not just link these pipes to test if it is the solenoid at fault?

Cheers.

It will go into limp home mode but not straight away & is a good test but all it tells you is that the turbo is working as it is bypassing the electrovalve, the electrovalve itself may be ok but just not being auctuated for whatever reason.

The ECU controlls the turbo pressure via the turbo electrovalve depending on what info it gets from various other sensors not just the boost pressure sensor.

Also the electrovalves for the EGR valve & EGR butterfly are the same as the turbo one so they can be used for testing.

uncle buck · Post by **uncle buck** » 04 Nov 2009, 11:14

wheeler wrote:....The ECU controlls the turbo pressure via the turbo electrovalve depending on what info it gets from various other sensors not just the boost pressure sensor....

With a problem like the OP described the 2 main suspects would be the boost control solenoid & the Turbo pressure regulator, It would be wise to rule these out before looking elsewhere.

Cheers.

HDI · Post by **HDI** » 04 Nov 2009, 11:34

Also , linking the 2 vacuum tubes will just fully open the wastegate as the vacuum pump will be linked directly , so there will be very little or no boost. To check the turbo just disconnect the vac tube to it from the boost control solenoid.
BTW , it's still the ECU that controls boost pressure