xantia HDI Intermitent turbo lag

[Dannyboy]

2.0 HDI Xantia with 180K....goes well but has developed above problem. Occasionally when accelerating the turbo does not kick in at the usual 1,500 / 1,800 rpm and the car feels sluggish...then kicks in at 3,000 rpm and you get the boost. If you feel it is not kicking in , by backing off the throttle and gently reapplying the boost returns at the lower rpm. It is intermittent. Power delivery is good when it works normally. I checked the waste gate linkage on the side of the turbo and it appears free...lubed it with WD40 anyway. I can`t see where the pipe from the waste gate goes to but the part I can see appears to be in good condition. Reading some of the forums suggests the waste gate is actuated by an electronic switch...could this be faulty ? I don`t have any engine management lights on . Any advice appreciated..................rgds.....Dannyboy.

[citroenxm]

Hmmmm. Sorry Ive NO solution, however, im in your boat too..

My HDi will sometimes be quick due to added tuning box, but however, like this morning, she was like a wet fart, and would hardley moove, I also noticed during this period excessive black smoke from the rear!

However, once she had warmed up a couple miles down the road, she was back to normal!

So I dont know either, but it is annoying. Theres something some where a miss intermittently..

Paul

[Deanxm]

wategate seizing/sticking a bit maybe, after a bit of working free's off? black smoke is not enough air for sure though so the turbo isnt bloing for one reason or another............................
Does the HDI ecu limit boost when cold or in low gears do you know?

D

[citroenxm]

Nope Dean.. they don't... its obvious the Turbo is not putting the air in.. but something is telling the Ecu the air is going in so the Ecu turns the fueling up....

Dodgy pressure sensor???

Paul

[Deanxm]

ah its not the air mass sensor is it that everyone keeps talking about that gives trouble and does strange stuff even though its only there as part of the EGR?

I take it the Lexia has not shone any light on the subject then Paul

D

[citroenxm]

It wont d as the Ecuador light is not on.. if I had a generic set of live parameters to compare too then that may throw something up...

Paul

[dieselnutjob]

The 90bhp has a mechanical wastegate whilst the 110bhp has an ECU controlled wastegate.
If it's a 110 it might be worth buying and fitting a new boost control solenoid as they can wear out and are a cheap and easy swap.
Also if you are loosing vacuum anywhere it will affect the turbo.

[Dannyboy]

Hi dieselnutjob......sounds like good advice.......will source a replacement..........easy to change you suggest ? ......access is good ?
Rgds..........Dannyboy

[citroenxm]

The vacuum solinoids on the 110bhp are located by the drivers side suspension unit... just by the cam belt cover.. there's two of them together.. one does the egr the other the Turbo...follow the vacation pipes to see which is the wastegate one... connect correctly.. incorrect connection and engine running may put the diagnostic light on and limp mode on resetable with a Alexia... been here so I know.. not with the current car though..

Paul

[dieselnutjob]

two push on rubber pipes
two bolts
one electrical plug

make sure you know which way round the rubber pipes go
it matters

[Dannyboy]

Tks for info gents.....I noticed the part numbers are the same for both the turbo boost and EGR solenoids so I interchanged them taking care how the pipes were fitted............made no difference. It`s highly unlikely they are both dodgy or is it ? The vac pipes in general appear to be in good condition.........looks like i`ll have to check for a vac leak. This snag is becoming dangerous........just when you need the boost , ie...overtaking ..you plant the wellie and wait and wait . It seems to be worse when the engine is warm.....always get the boost ( not intermittent ) when accelerating from cold or within a few miles from start. ..........dannyboy.

[DickieG]

Check that the vacuum pipes aren't blocked with crud and that air can flow freely through them (Citroen service bulletin).

[Dannyboy]

tks dickeyG...will do............rgds Dannyboy

[Dannyboy]

Hi Gent`s /DickyG.....I did`nt get to check my vac pipes yet...but just a thought......Does the system work like this on the 110 bhp eng ? ......ECU senses airflow thro the MAF after throttle opens up. ........schedules more fuel......higher exhaust gas flow spins up the turbine on the turbo which spins up the compressor on the turbo....and so boost happens......when the boost is near it`s limit the waste gate operates to limit boost.......where does the vac come in ? Is the boost vac controlled by a sensor ? could I have a dodgy sensor or a dodgy MAF ? .......an explanation of how it works if I have gotten it wrong might help me figure my problem out .....tks in advance..........dannyboy.

[HDI]

Vacuum is continuously supplied by a vacuum pump, this is fed to one side the boost control solenoid valve. The other side of the solenoid valve is fed to the wastegate actuator. The valve can be anything from fully closed to fully open. When the boost control solenoid operates to control the wastegate to control boost pressure, it is fed with a pulsed signal from the engine ECU to open the solenoid according to the duty cycle of the signal, thus applying vacuum through the solenoid valve to the wastegate actuator. The signal is a series of pulses separated by time intervals, the time interval represents duty cycle. This is very rapid though, in the order of 10's to hundreds of pulses per second.