Logged some data on the way home last night.
Gave it a boot full in 3rd.
I really dont like how high the upstream pressure is going.
Need to do some investigating.

 

Let me give it a try ......................

IMO the thing to do is to confirm you are actually getting that ridiculous pressure without the ECU puking about it in some way ..................

So first thing to do is to get a old-school "boost/manifold vacuum" gauge and hang it off any manifold port - confirm what you see there on the manifold pressure sensor

........... and since you seem to have nice tools there - start the logging function and log ALL engine parameters simultaneously for a trip - start logging when cold and engine off, do your trip, come back and let it idle, shut down logging and post results here lets see

 

Yes I agree.
My first mission is going to remove the upstream sensor and pump some pressure into it and check if its reading correct values. Just hope its the sensor thats up the shoot.

 

That DPF regen ................. why was that done/required?

 

The 1.5 bar expected boost will be 1.5 above atmospheric so you should see
about 2.5 bar, my dci 1.5 shows 32 psi about 2.2 bar at full power, I know it's
not the same engine but it gives some idea, 4 bar is high though are any linkages
on the turbine and it's wastegate free to move.

 

Thanks for the replies.
Its my own vehicle and only do a few miles to work and back.
By the time I get to work its only just up to running temp.
I wait until its got around 50 grms of soot in DPF and then do a run in 3rd at 50 ish MPH for half hour.

 

Ralph, its not 1.5 bar expected boost.
Its upstream turbine pressure.
Exhaust manifold.

 

You have the nice tools - is the exhaust flow rate measured and MAF flow rate measured the same throughout the rev range? ........... post a log


your manifold pressure figure of 2.6 in that screengrab is close to what it should be just as @Ralph said - but that is the place to start

If you can confirm you actually see that boost figure the exhaust flow MUST go somewhere else you will not be building boost .............. and the ECU normally complains much better about such high exhaust back pressures

 

Will do.
Workshop time today for the old girl.
Going to start by checking the sensor is reading correct values.
Cant believe how well it runs if it is having this amount of back pressure.

 

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

 

Ok that's a good test but if the sensor's voltage range is 0 - 5V for a 0 -1500mbar range as per

Pressure upstream of turbine.

Here is a weird one. 2012 2.0 Dci Espace 150 hoss power. Runs fine. no error codes or warning lights. Did a regen on the road last week logging data. 50 MPH 3rd gear. Regen comleted fine down to 0 grms of soot. Looked at data afterwards of the run and noticed at times the pressure upstream of...

www.renaultforums.co.uk

, what sort of voltage gets fed to the ECU in order to make it think that its seeing 4Bar?

Did you confirm the voltage seen on the sensor with the 1500mbar reference pressure applied?

 

 

Voltage is close to 1V at tickover and increases as the pressure increases.
Sensor maxes out at 3.95 bar.
Whatever voltage is computer is seeing the correct pressure.

 

So in that pic of yours ............... 1.82V = 3.697 Bar? ......... and that on the expected 1.5Bar range ?

 

Putting it another way:

Lets say downstream of turbo the exhaust pressure is around 0.4 Bar + at 4000rpm on a good flowing exhaust...............

You need quite a lot of work to be done by the turbo at 4000rpm ................and the work is reflected in the pressure differential across he turbo so one would expect something around the reported 4 Bar absolute upstream of the turbo to get that energy into the turbo's impellers

Question is why is Autel tool telling you to expect a range of 0 - 1500mBar? ................. what is Clip telling you to expect - also only 1500mBar or something else like 5Bar?


IMO the ECU as I said, pukes very quickly if the measured parameter value is outside the expected range in the ECU - why is it not puking currently? ........... is it happy with the value and Autel doesn't know what its talking about?

 

Here is graph of sensor voltage and pressure.
Clip does not give a max.
Computer starts to read from atmospheric.
Pump 1 bar into sensor and it reads 2 bar ish.
If cat is blocked manifold pressure will go up.
I would expect max to be 1.5 bar.
Will check with Renault what suggested max is.

 

I am interested in the eventual answer to your expected pressure range question too, but since I cannot source specific reference material I cannot help and currently don't have one of these animals I can slap a scanner on for comparison.

I would say that as long as there are no complaints from either the car or Clip (in particular) then drive the thing and forget about it - the ECU is really good at moaning when required

 

Engine Exhaust Back Pressure

 

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

 

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 ..

 

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

 

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.

 

 

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...............

 

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

 

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)

 

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.