Progress on my power loss issue !!

HDI · Post by **HDI** » 16 Nov 2009, 23:27

Finally managed to remember to bypass the boost control electrovalve before driving home tonight. This is to check if that is causing the intermittent power loss.
Well , it would seem so. Before bypassing , the engine speed at which boost developed could be anything between 2 - 3000 RPM and it was always inconsistant boost even then. With the bypass , boost is smooth and predictable and it comes in around 1800 RPM , doesn't make any noticable difference to maximum power though.

The power loss problem didn't occur either , I'll try again on a road I can almost guarantee it to happen though , to be sure !

If the problem is cured by the bypass then I just have to be sure it's the electrovalve or the boost pressure sensor.

citroenxm · Post by **citroenxm** » 17 Nov 2009, 20:36

It should be the elctro valve... Ive had one of these go on a customer car, suddenly..

Paul

wheeler · Post by **wheeler** » 18 Nov 2009, 16:20

If unsure swap it with the EGR electrovalve, they are both the same.

HDI · Post by **HDI** » 18 Nov 2009, 17:38

Thanks , but already did that , no change.

Citroenmad · Post by **Citroenmad** » 19 Nov 2009, 10:41

The MAF sensor can have a big impact on performance.

We had to replace one on the old 2002 2.0HDi 110 C5 as performance was lacking. A replacement geniune MAF cured it and it was like a different car to drive. Though i would not recommend a aftermarket MAF sensor, as its not worth changing it unless you go for a genuine item.

HDI · Post by **HDI** » 19 Nov 2009, 10:46

Thanks , but done that too

It is definitely related to boost control just need to determine that it is the electrovalve.

HDI · Post by **HDI** » 19 Nov 2009, 14:20

Well , it's not the electro valve !! Just used a road where the fault virtually always happens , and it did !! The ECU must be cutting fuel. Looking more like the boost pressure sensor now

Anyone know where that is ?

citroenxm · Post by **citroenxm** » 19 Nov 2009, 15:04

Yup ON TOP of the intercooler unit, behind PASSENGER head light infront of the radiator...

What about the sensor on the END of the pump, facing the fuel filter, have you tried that?

Paul

HDI · Post by **HDI** » 19 Nov 2009, 15:22

Thanks , I'll also examine the pump sensor.

steelcityuk · Post by **steelcityuk** » 20 Nov 2009, 10:59

After bypassing the boost solenoid can you check that the ECU isn't detecting a fault (overboost perhaps) and cutting the power?

Steve.

wheeler · Post by **wheeler** » 20 Nov 2009, 11:10

steelcityuk wrote:After bypassing the boost solenoid can you check that the ECU isn't detecting a fault (overboost perhaps) and cutting the power?

Thats a very good possibility, bypassing the electrovalve is a good short term check (ie half a mile) to see if the turbo is working, if you leave it bypassed the ECU will eventually detect overboost & kill the power. The ECU knows it should'nt be seeing full boost when the accelerator is only pushed halfway for example. This will most likely also throw up a fault with the boost pressure sensor which could fool you into thinking the sensor is faulty, so just be aware of that.

HDI · Post by **HDI** » 20 Nov 2009, 11:18

Hear what you say but the fault feels exactly the same with the EV connected or bypassed. So it could indeed be the ECU detecting overboost but I think it's due to the sensor reading incorrectly. Without a Lexia of course it's all shooting in the dark really !!

The sensor is the only way the ECU can detect overboost , so thats the prime suspect I think.