Turbo swap or new car, that is the question...

[PNuT]

p.s did you use any additional sealant?

[Alex.]

I wouldn't rely on torque to give you an accurate boost reading. Get yourself a proper gauge.

I only used Torque as I had used it to get an indicative reading back in March. The reading was the same as before the dump valve blanking plate (6psi), which leads me to believe that the dump was working. The dyno guy said that the boost was holding at 4psi...

If there are no obvious leaks, I would be looking at the actuator (in fact I am, as I have the same problem with mine), if it's tired, it may be opening too early.

That would be the next thing to try, before a full up turbo replacement.

I suppose I could send him one of those as well!

As I can't simply blank off the wastegate, would you be prepared to sell (or loan... ) me your spare wastegate to try?

p.s did you use any additional sealant?

I did put some sealant around the o-rings, just in case...

Browsing ebay, there appears to be a seller in Germany that has 16Ts for £210. Would these be the cheap Chinese versions and would they actually be worth using?
http://www.ebay.co.uk/itm/2620781215...%3AMEBIDX%3AIT

Or even a company based up in the West Midlands at £126.75!
http://www.ebay.co.uk/itm/2004984312...%3AMEBIDX%3AIT

Alex.

[PNuT]

first question is what is the exact number of your engine?

B5234T6

in that format if you can!

There are a number of ways to check the wastegate without changing it! the first you must be very very careful doing! especially at low rpm!

if you disconnect the pressure pipe from the bottom of the turbo to the TCV/BCS you will get all the boost your turbo can muster! ULTRA CAREFUL! you will soon know if your turbo is boosting!

to check its opening pressure connect that pipe directly to the wastegate actuator & that will give you a clue to its opening pressure as it will just hold the boost it is set at! I would try this first!

4psi sounds like the actuator pressure!

have you had the codes checked?

I wouldnt rule out a blocked cat at the moment either!

[claymore]

It's not going to be the turbo, mine was completely knackered and still boosted to 22psi, either your waistgate is stuck open (take the waistgate arm off the turbo and make sure the flap moves freely)

this was my knackered turbo,

[kmb]

That's like a Penelope Pitstop smokescreen button... cool but not something I want to see on my car

[ExternalError]

you should try driving behind him for the 1st 20 miles of a trip to shell island after he fixed it as it still smoked while burning the oil off the cat

[PNuT]

It's not going to be the turbo

No, I wouldn't expect it is a problem with the turbo itself but it does need a few things to be right for it to spool & produce compressed air....

I would assume the Waste gate actuator is doing something as it is holding a nice steady 4psi on the rolling road...

connecting the boost hose directly to the wastegate actuator will tell us the opening pressure of the wastegate actuator, if this doesn't change the car at all then it is most likely an issue with the turbo control circuit it self....if it still boosts but much less than the factory specified opening psi of the wastegate actuator then we should know it either needs adjusted or a new actuator...

running the turbo without the pressure pipe connected is just to check we have enough exhaust gas flowing for the turbo to spool properly & produce compressed air! obviously if the wastegate is stuck open this will prove nothing but I wouldn't expect much boost if that was the case....

[Alex.]

first question is what is the exact number of your engine?

B5234T6

in that format if you can!

Almost... I know it is a B5234T and 3, I think.
Definitely a T5 engine with ME7.

There are a number of ways to check the wastegate without changing it! the first you must be very very careful doing! especially at low rpm!

if you disconnect the pressure pipe from the bottom of the turbo to the TCV/BCS you will get all the boost your turbo can muster! ULTRA CAREFUL! you will soon know if your turbo is boosting!

to check its opening pressure connect that pipe directly to the wastegate actuator & that will give you a clue to its opening pressure as it will just hold the boost it is set at! I would try this first!

4psi sounds like the actuator pressure!

have you had the codes checked?

I wouldnt rule out a blocked cat at the moment either!

I'll have a check of the wastegate, hopefully without busting something else!

Alex.

[PNuT]

actuator pressure for your vehicle if B5234T3 is 4.35psi.......

[Alex.]

actuator pressure for your vehicle if B5234T3 is 4.35psi.......

Is the actuator in the wastegate?
I understand the fundamentals of how a turbo, wastegate and dump valve work, how does the actuator fit in?

If it is looking likely that one of the items attached to the turbo is at fault and that the turbo is possibly the original one, that has done 151k miles, would it be worth buying the £126 turbo assembly from ebay (link in previous post) and fitting that?

Alex.

[jamesy12345]

Is the actuator in the wastegate?
I understand the fundamentals of how a turbo, wastegate and dump valve work, how does the actuator fit in...

the actuator is the cylinder that sits above the turbo cold side, with an arm connected to the wastegate. Inside is a piston that moves the arm depending on pressure sent to the actuator by the BCS

Gold thing in this photo:

[PNuT]

Unless you are using excessive oil I would keep the turbo you have!

It may be you have a code hidden & the ecu is not allowing the turbo to boost to the proper level...

for instance my car recently has been throwing code 2-3-1 fuel trim because I have the wrong injectors fitted, it boosts properly for one journey & then the ecu stops boost above actuator pressure.... once I reset the codes it works again!

It hasn't brought the engine management light on for this error though!

[Alex.]

the actuator is the cylinder that sits above the turbo cold side, with an arm connected to the wastegate. Inside is a piston that moves the arm depending on pressure sent to the actuator by the BCS

Ah, enlightenment dawns!
So if the actuator has an activation pressure of 4.35psi, how does that correlate to a boost pressure of 15psi?
Or indeed, the boost only holding 4psi....

Alex.

[Alex.]

Unless you are using excessive oil I would keep the turbo you have!

It may be you have a code hidden & the ecu is not allowing the turbo to boost to the proper level...

Oil consumption has not changed in years, she uses some but not excessive.

During the diagnostic dyno session, the mech read the codes and said there was nothing relevant.
I have had the ABC/TRACS lights and codes, so that is another job I need to get round to...

Alex.

[jamesy12345]

Ah, enlightenment dawns!
So if the actuator has an activation pressure of 4.35psi, how does that correlate to a boost pressure of 15psi?
Or indeed, the boost only holding 4psi....

Alex.

I tried to find a decent link with some pictures (for my benefit as much as anyone's) but didn't so hope this makes sense

When the ECU/map wants the wastegate closed, the BCS sends zero (gauge) pressure to the actuator

When wastegate is required to be open, the BCS bleeds off boost pressure down a level sufficient to overcome the pressure set by the actuator spring (4/5 psi)

If 16/17/18 psi equivalent spring was used, & no BCS, it would be more difficult to control the boost - it would be more on/off response from the turbo rather than being progressive

Probably.

//edit

http://www.renault-5.net/shemas_turbo1.htm#animation

good animation above showing how it works without BCS...although on most cars the throttle body is after the turbo..!

[PNuT]

What I don't think has been mentioned is being an Me7 car you should have a MAP sensor....

If that is faulty & giving the ecu the wrong reading ie the 4psi you are getting is reading 10psi then the ecu thinks everything is fine & dandy!

no codes & 4psi steady!

[Alex.]

That was a productive drive home from work!

I connected the pipe from the bottom of the turbo to the wastegate, torque reported just over 5psi. So this is consistent with previous times when 4 psi was reported as about 6.

Then put the wastegate pipe back on and left the pipe from the bottom of the turbo open to the air.
Moderate application of the throttle and a close eye on torques gauge.... I have a TURBO car!!
A pressure of 12 psi reported, but only for a short time and not full throttle.

Does this mean I need a new wastegate? Much cheaper than a turbo.

Alex.

[claymore]

are you certain you have the pips the correct way around on the tcv?

[Alex.]

are you certain you have the pips the correct way around on the tcv?

I had the same thought myself last night! So I fired up the old unreliable (XP) laptop and checked Vadis.
According to the figure there, my pipes are connected correctly.

Top of the TCV to the bottom of the turbo.
Middle of the TCV to the wastegate.
Bottom of the TCV to the dump valve.

Alex.

[claymore]

Are you sure, that isn't how it is on a pre me7, but I don't know this modern stuff, I would just put an mbc on it , I never use the tbc's on any of my engines