[LvR]

Thought you would read this too @ours2012 ............. great info ................ do you perhaps have any hidden stash of reference material to enlighten us on the upstream turbine pressure range on the turbo to be expected?

I know that most turbos generally run around 2:1 realistically (ideal would be 1:1) .............. so id say at 1.6Bar boost one could expect 3.2 Bar upstream turbine pressure is not too far off that last 3.4 Bar in the last picture ................... but I just don't know what the efficiency of these turbos are like and what EXACTLY to expect

 

[ours2012]

Had a look, and could not find anything ,


Would be thinking along the lines
How many times the DPF needs Regen is it all down to not actually using the car and soot through all the system is making a restriction
OR
Has he got back pressure somewhere else in the exhaust system, even though its running fine


My thoughts would be pointing to a baffler in the rear exhaust box, just because its running so well and the amount of back pressure ( Again, dont know if its that's acceptable on this engine ) does not seem to have an effect , is there an issue,, or not
hard one to answer ..

 

[LvR]

Thanks for checking - thought I am being denser than normal - Yeah - Id say if Clip is happy and no Christmas tree light flashing on the dash just drive the thing.

Best one can do without design engineering knowledge is look at exhaust and turbo related temperatures and if also in normal "expected" range then whatever perceived abnormal "obstruction or blockage" is present is of no consequence

 

[george formby]

Thanks for your replies guys.
My car being one of the last RHD ones made is a bit of an oddball.
The DPF filter has only one pressure sensor pre DPF.
There is no post DPF sensor,.

So the way I see it at the moment is that I have pressure upstream of turbine that is quite high.
The flow of sensors and components is, exhaust manifold - turbo - pressure sensor - cat - pressure sensor - DPF.
The first sensor has been checked to be reading correct and giving a high value up to 4 bar.
The second sensor pre DPF is reading no more than 0.3 bar when giving it welly.
With it being silly Renault the upstream turbo sensor starts to read from atmospheric pressure with ignition on.
The pre DPF sensor starts to read from zero,
This is telling me there is possibly a restriction somewhere in the cat area,
Just want to get to the bottom of it before I get clouted in the gonads with the turbos internals.
Will have a trawl through Dialogys in the morning and see if there are any values suggested.

 

[george formby]

Thanks for your replies guys.
My car being one of the last RHD ones made is a bit of an oddball.
The DPF filter has only one pressure sensor pre DPF.
There is no post DPF sensor,.

So the way I see it at the moment is that I have pressure upstream of turbine that is quite high.
The flow of sensors and components is, exhaust manifold - turbo - pressure sensor - cat - pressure sensor - DPF.
The first sensor has been checked to be reading correct and giving a high value up to 4 bar.
The second sensor pre DPF is reading no more than 0.3 bar when giving it welly.
With it being silly Renault the upstream turbo sensor starts to read from atmospheric pressure with ignition on.
The pre DPF sensor starts to read from zero,
This is telling me there is possibly a restriction somewhere in the cat area,
Just want to get to the bottom of it before I get clouted in the gonads with the turbos internals.
Will have a trawl through Dialogys in the morning and see if there are any values suggested.

 

[george formby]

This guy would have a baby.

 

[LvR]

This guy would have a baby.

Nothing new said there that has not already been said imo ................ in terms of his definitions my own 0.4Bar allowable backpressure I estimated for a usable exhaust simply got lowered to o.3 Bar by his standards, so call me wrong on that - other than that what does Clip or any other Renault sources reference say?

He didnt even touch on upstream turbine pressure...............

 

[george formby]

Had another look at Clip.
I does indeed give a max value of upstream pressure.
1.5 bar, same as Autel.

 

[ours2012]

but *not any fault codes. *

 

[george formby]

Nope, no codes or moaning of any kind'
Just ran it up in the workshop to 4k with cat oxy sensor removed.
If the cat is restricted pressure reading will be a lot lower.
At the mo I dont think reading is any lower.
Will put it back together and do another reading.
Back in a mo.

 

[george formby]

2 tests done.
In road trim stationary in workshop holding revs at 4000.
RPM 4035
Boost 1.1 bar.
Throttle angle 22.5.
Pressure upstream of turbine 1593 mbar.

Remove cat o2 sensor
RPM 3986
Boost 1.118 bar
Throttle angle 21.4
Pressure upstream of turbine 1697 mbar.

This shows the cat aint blocked.
With the o2 sensor out playing with the revs slightly 3.5 to 4k turbine pressure would go as high as 2 bar.
Bleedin head scratcher this one.
The only thing to try now is remove the EGR blanking plate.

 

[LvR]

but *not any fault codes. *

THIS!

Autel copies what Clip's descriptions and definitions are .............. if the Clip reference material is possibly funky then Autel will simply echo that logic .................

Nope, no codes or moaning of any kind'
Just ran it up in the workshop to 4k with cat oxy sensor removed.
If the cat is restricted pressure reading will be a lot lower.
At the mo I dont think reading is any lower.
Will put it back together and do another reading.
Back in a mo.

You cannot get work done by the turbo unless you have a pressure drop across the thing - iow pressure higher on the manifold side than on the exhaust side ................. and ALL turbo have to obey this law of energy input - nothing is for free. Grab any non-racing turbo spec on an engine under load and you will find they operate with a varying turbo differential pressure to boost pressure ratio of around 2 or better - in ideal rev range you will have a ratio closer to 1 ...................and your measurements fit nicely with this characteristic ................ so as I said before your setup is most likely 100% within expected behavior - if you calculate the ratio around max efficiency (+-2000 rpm) you will see this happen

2 tests done.
In road trim stationary in workshop holding revs at 4000.
RPM 4035
Boost 1.1 bar.
Throttle angle 22.5.
Pressure upstream of turbine 1593 mbar.

Remove cat o2 sensor
RPM 3986
Boost 1.118 bar
Throttle angle 21.4
Pressure upstream of turbine 1697 mbar.

This shows the cat aint blocked.
With the o2 sensor out playing with the revs slightly 3.5 to 4k turbine pressure would go as high as 2 bar.
Bleedin head scratcher this one.
The only thing to try now is remove the EGR blanking plate.

With no load on the engine you cannot do a sensible turbo backpressure test - the ECU limits the amount of boost to near 0 since there is no need for it to achieve the required throttle input desires of the driver - hence your measurement results. You need to load the engine. With no real load on the engine there is no real angry exhaust flow/manifold pressure generated - the engine is effectively reacting like a non-turbo engine


Also:

You earlier reported "DPF pressure is fine never going over 0.2 BAR. " ................... iow when speaking exhaust backpressure and starting from the exhaust manifold upstream of the turbo - your last complete exhaust manifold presure reported was 1.698 Bar . The exhaust tip is sitting at around 1Bar (ambient) ............. so in total your backpressure seen by the engine is about 0.698 Bar ................ of that you are dropping 0.2 Bar across the DPF so you are left with an effective 0.498Bar due to all the additional components ................ earleir I said I felt 0.4 Bar on a good exhaust is imo ok - so you are again right back to that figure and that includes the effectively unloaded turbo (its not making boost so its acting as if its nearly not there)

 

[george formby]

Do Autel copy off Clip? Who knows.
Using Clip 178 at the mo. That came out quite a while after 2012.
Is the software not done by Bosch?
Would it have big mistake like this in it for so many years?
Autel software is up to date as of Saturday.
Upstream turbine reading starts at ambient.
DPF reading starts at zero no matter what the ambient pressure is.
Have got a local pal with a Vauxhall van of same year with same donkey.
Will get him to swing round to the workshop and will have a plug in.

 

[LvR]

Upstream turbine reading starts at ambient.
DPF reading starts at zero no matter what the ambient pressure is.

It looks like you don't yet have the basics down of the 2 different types of pressure sensors found on the exhaust:

Absolute pressure sensor:
1. Single input nipple
2. Will ALWAYS start reading from ambient - because no matter what you do the whole of the exhaust system (from the rear of the vehicle where the exhaust tip is, to the inside of any cylinder with an open exhaust valve) will be at ambient without the engine running
3. Used where one is interested in the pressure values at a specific point.

Differential pressure sensor:
1. Will have 2 nipples on it
2. Should/must always start reading from 0 - because the way its mounted on the exhaust in this case, the pressure on both nipples is exactly the same - ie ambient with engine not running.
3. Used where one is interested in seeing how much extra pressure drop a certain component is experiencing - the software has some serious maths involved using the pressure differential reading to calculate the soot content of the dpf in grams - eg for use during DPF regens and the control of that
4. Some ECUs will also implement an "auto zero" or "offset compensation" function - before the engine is started it will look at the differential pressure signal and add or substract the offset seen THEN from any measurement reported after the engine is started in order to have a more accurate parameter value.

IMO you are incorrectly assuming either/both Clip or/and Autel is wrong on the specific parameter's reporting without knowing the exact purpose of the parameter - the parameter's description may not be clear ito when you are supposed to measure the upstream turbine pressure. I don't know its specific purpose or limitations either - I don't have specific engineering knowledge of the software and/or logic driving it - but I do know there are many parameter values getting reported that have only a very specific range of usability.

Take for example the common O2 sensor voltage parameter - you have to be aware of the workings of the sensor - ie - the need for a specific minimum temperature, whether its a narrow band or wide band type of sensor ...........and more importantly what the ECU logic implemented is ................... in particular the need to ignore its value reported when at full throttle or above 5500 rpm else, if you look at just the voltage on a scanner with a variable engine speed and load it would not make sense at all..............

The same goes for the upstream turbine pressure - you need to understand the mechanical and thermodynamic principles involved else you are going to be chasing your tail for no reason

 

[george formby]

Yes I do understand.
This DPF has only one sensor.
The only thing I am trying to suss out here is why my upstream turbine pressure is out of spec using 2 tools.

 

[LvR]

I really think you do not understand so I am out.
Good luck - I hope you find the answer you are looking for..........

 

[george formby]

Things are looking up.

 

[ljubisa.graovac83]

Well that sensor was a little monkey to get to.
Removed and pressure tested up to 1.5 bar.
Reads spot on. Tested with 3 different pumps.
So whatever is going off the exhaust side of the turbo is getting some serious pressure build up.
Checked operation of the variable vanes on turbo while I was down there.
They are working fine.
It has got a egr delete plate fitted but dont think it is that causing the problem.
The air does go round and round after all.
Will remove it and re test.
Also need to find what Renault list as max pressure.

Hi where is sensor located on Renault Traffic 2012 2.0cDi? I can't find it