[redren]

Is there likely to be a lot of difference in the pressure coming out of the air pipe to wastegate actuator when a car is revved on the drive compared to it being driven and under load?

 

[Ralph]

Yes lots

 

[redren]

Thanks, my actuator isn't actuating...though a fair bit of air is coming through the pipe on the drive...attached to a foot pump the actuator opens at about 8/0 psi

 

[madnoel10]

I may be wrong but I was always under the impression the turbo wastegate actuator was vacuum operated.

 

[Ralph]

I don't know about your engine but the DCi 80 like mine as the boost limited to about 1.2 times atmospheric, so would expect the wast gate to be fully open at about 17psi but a scanner may show about 32psi as it's manifold absolute pressure.

 

[madnoel10]

What part are you testing - the actuator arm on the turbo or the MAP sensor unit itself (sometimes referred to as the turbo pressure sensor).

 

[Ralph]

I may be wrong here but I am under the impression that if we are talking about the same thing, you say actuator I think it;s a wast gate, that the valve should be closed allowing all exhaust gas to go through the turbo, only opening if the turbo boost gets too high, unless you have a variable vane turbo in which case I am even less sure, but as far as I know only the DCi 100's and above have them.

 

[redren]

Can I join in?
First I have no technical knowledge whatsoever so I can only report what I see and call things by what I believe to be the right name.
So,we are talking about a pipe that goes into the top of the (and I'm sure it's the correct name) wastegate actuator...when enough air pressure is pushed through the pipe the actuator pushes its rod out which opens a gate...this gate confusingly doesn't divert the gases to waste but the opposite...it diverts them to spin the turbo, and that is what is not happening,there is pressure there but even under load not enough to crack the actuator...I've looked and looked for leaks but can't find anything.
Am I reading the situation correctly ?

 

[madnoel10]

Any turbo I have worked on the actuator is operated by vacuum. Trace the pipe you refer to and see where it eventually ends up. On most diesels it evetually reaches the vacuum pump on the end of the camshaft.

 

[redren]

Most comments I have read seem to talk of vacuum actuators yet the pipe to this one definitely blows PLUS the actuator it self (and a new one I tried) blow out not suck in.
By the way the car is running a little better now (still not good -still no turbo ) after I disconnected the MAF...is there any downside to doing that?

 

[madnoel10]

If the actuator works on air pressure rather than vacuum what generates the pressure?

Disconnecting the MAF sensor forces the ECU into default mode thus over-riding many of the engine sensors.

Have you traced the source of the pipework as already suggested?

 

[redren]

A large bore hose comes from the intercooler to - for want of a proper word - a big silver block, the actuator pipe attaches to the top of this and directly past this the EGR bolts on the side - I did say at the start I had no technical knowledge !
Is that description any use?

 

[madnoel10]

Judging from the limited description I assume the big metal block may be the inlet manifold - I can't be sure.

Yes the pipe coming form this will emit pressure but only if the turbo is pumping air. This pipe should go to a turbo gate control unit which in turn activates the physical gate on the turbo.

I appreciate you have limited knowledge - is there any chance of posting up a few pics - it may help get a response.

 

[Ralph]

If you can get hold of one try swapping the MAP sensor for a known good one.

 

[redren]

Pics hopefully on their way and as to the MAP sensor I don't think there is one...just a MAF
(if that sounds a bit like I know what I'm talking about - don't be misled)

 

[madnoel10]

Without a MAP sensor how on earth is the turbo gate going to be regulated?

 

[Ralph]

Ok swap the thing you think is a Maf is then.

 

[redren]

I know what MAF means and I know where it is...what does MAP mean and where would it live?
Also I know what a waste gate does but what does a turbo gate do? - my ignorance knows no bounds!

 

[redren]

O.K it's Manifold Air Pressure..but I still can't find one ...and the car is a lot livelier with the MAF dis connected.Will any of this give a clue to my main problem of the turbo not working?

 

[redren]

Just a thought...that silver rectangle sitting between the EGR and the boost solenoid on the first photo...that couldn't be the MAP? could it?