Td5 D2 engine - Fitting the ProVent (3)

More problems with the plumbing.

Waiting around for the 90° hose reducer to arrive proved to be a real hassle. I mentioned earlier how I bought everything off the Internet as trying to procure what I needed in the local stores was a complete waste of time.

Thinking that I had everything needed, I was thwarted at the last moment by the unforeseen need for a 90° elbow that would also reduce its internal diameter (ID) from 25mm to 19mm. A fairly specific bit of kit but readily available online. 

The supplier I choose to order from had already supplied the clear hose I used for the install. They also included two hose clips in the purchase price which is what caught my eye.

After waiting over a week thinking it's got lost in the post, an e-mail arrived from the suppliers informing me that what I ordered in black was not in stock and would I accept one in red or blue? I should have asked for the money back there and then but instead I opted for a 'blue' alternative. It too failed to arrive and I had to open a 'dispute' through e-bay to get the money back. The money was repaid the next day, but it was close to the 30-day limit..

The whole experience just made me feel taken advantage of. I started to research the seller and found out they use multiple identities all linked by the same address in Mirfield. The feedback ratings over all the sites told their own story.. 'avoid'. I ended up feeling that they were just playing it out for time to defeat the 30 day e-bay dispute ruling. It wasn't the money issue (£8.67) but rather the thought of having been 'lured-in' by them, the waiting around and the paranoia!

I turned to another supplier 'Demon Motorsport' who restored the faith delivering within two days... I had earlier ordered the 'straight' reducers from them and would happily go back there again.

At the time of ordering, they only had the elbow reducer in 'blue' silicone. I am personally averse to all that 'boy racer' colourred silicone hose scene but things here are getting a bit desperate!

The workbench spread of plumbing bits.

Showing the two 25/19mm reducers ready to assemble onto the ProVent.

The ProVent body is already mounted on the engine bay bulkhead so all I needed to do was attach the hoses and route them around the engine.

And that's where the problems began. It quickly became apparent that the new hose will not bend to the shape needed and more elbow connectors will have to be used...

I decided to use the original Td5 rocker cover hose as it has the 's' bend already moulded into it and sits nicely under the acoustic cover.

I had also decided to remove the fitted Depression Control Valve (DCV) mounted on the turbo intake. 

The ProVent unit comes complete with its own depression valve to control the intake vacumn and removing the fitted DCV would help free-up space to route the connecting hoses.

Began to bark up the wrong tree.....   After staring at the problem of the hose routing, I decided to hunt down some old spare shaped hoses and came accross this elbow section that was 19mm ID at one end and reducing to 16mm at the other.

This spare hose was originally about 2 foot long with only the elbow section being 19mm ID. Luckily that was all I needed. The above photo shows the reduction in diameter at the horizontal end.

That was trimmed off and the 19mm straight connector was a tight push fit ..

A rather neat solution I thought, but it turned out to be not suitable as the 'elbow' was too tight an angle, a 45 degree bend would be more appropriate.  

I could have simply ordered a 45 deg hose bend, but I was now mindful of the increasing costs of this install, - never mind the length of time taken to complete it!

Thoughts turned to adapting what had already been bought. This meant having a go at shaping the clear hose with heat to get it to take on a more useful shape.

The technique was simple and easily controlled...

I placed a15mm pipe bending spring into the 19mm hose to give some internal support and then tied the end with some garden wire just to hold the shape. 

The hose was then placed into a saucepan and hot water poured in. The curve of the saucepan aided the 'moulding' of the hose and it was left there for about 15 min with top-ups of hot water along the way. 

When removed, it was noted how the metal spring itself was warm to the touch. The hose clearly showed an increase in its 'bend' and although it relaxed a little I felt confident sections of it would now be usable and indeed save the cost of a 45 deg silicone hose..

This is the plastic hose after the heat treatment and at rest showing the tighter curve that it now has. This proved to be ideal.

Had the heat treatment failed, another trick I could have used was to fabricate a wire spring to support the hose bending. I got the idea from the bracket found at the back of washing machines to 'shape' the outlet hose. When I looked on line I found these...

They are called 'unicoil' and are not to be confused with 'helicoil'. They are commercially available in various sizes, but could easily be fabricated from thin wire..

Above photo shows the heat treated hose during fitting. The curve in the hose is its natural state (after the heating) and it's under no tension whatsoever... a much better fit. 

Visible on the hose are two pieces of masking tape I used to mark where to cut the hose to get the best fit.

TD5 D2 engine - Wastegate Modulator (2)

Looking through the latest Nanocom test data, the results are not conclusive. Still don't believe Hx is developing full boost, and reasons for that are not so obvious...

-  The Wastegate Actuator can be further adjusted to deliver more boost.
-  The Wastegate Modulator valve may be 'sticky' or leaking internally.
-  The MAP sensor could be dirty...

On a positive note though, the general performance of the engine has improved. There is a definite progression to the turbo when it gets applied and the acceleration and cruise at speed is good. I guess I just want more of that performance available lower down the rev-band.

Suspicion has turned again to the Wastegate Modulator mounted on the engine block. It can be seen to receive the signal from the ECU to operate at the various 'Duty-Cycles' of up to 40% which is the MAX value. Although the signal might be getting through I can't be sure that the internal valves in the Modulator are performing as they should.

There is a Nanocom enabled test setting for the Modulator that will send a test signal pulse to the Modulator with the engine off. It should be possible to hear the solenoid inside the Modulator clicking or indeed 'feel' it doing so by physical contact. I did try this the other day, but I was unable to hear the solenoid clicking and the physicality of the location means an assistant is needed to operate the Nanocom while I get physically close to the Modulator or use the old stethoscope trick.

There is a text message on the Nanocom about 'testing complete' but I don't know whether it will throw up a fault message or not.

There is a need to fully understand the operation of the Modulator. The data logs show signals are sent to the Modulator and Hx never overboosts so I am tempted to say the Modulator works, but the data also shows Full Boost on Hx is not quite what it should be!

MODULATOR OPERATION .

Here is what I understand about how the Modulator works. Numbered references are from the Rave diagram 'M192564' that depicts the Modulator on the engine block..

Boosted air pressure from the turbo outlet pipe is bled off through a small-bore flexible tube that enters the Modulator from below (2-lower) and exits at the top right (2-higher) to supply the Wastegate Actuator with pressure.

This will allow the increasing turbo generated boost pressure inside the thin-bore pipe to increase and begin to operate the Wastegate Actuator on the turbo unit. 

This is essentially the same as having the Defender Td5 set-up where the pipe from the turbo outlet goes direct to the Wastegate Actuator. This set-up then depends on how the Actuator is adjusted to determine when the Wastegate valve opens and that governs the level and duration of Full Boost available.

It can lead to the condition of 'Wastegate Creep' where the turbo never delivers full boost because its Wastegate valve is operated too early in the boost generation cycle.

It can be seen that adjusting the Actuator's internal spring will determine at what pressure level the Actuator begins to open the Wastegate Valve. 

Increasing the spring tension on the Actuator will delay the opening of the Wastegate and increase the availability of boost pressure in the inlet manifold. It is a delicate balance to achieve, but it is easily done with care. The big question is knowing what boost pressure it should be developing and comparing that to what it is developing now.

Back to the Modulator.

The Discovery Td5 engine has the Wastegate modulator fitted in order to allow the engine to safely develop maximum full-boost turbo pressure for longer. This should have a positive performance gain over a non-regulated Td5, allowing the full performance of the engine to be used when needed under load for overtaking or hill-climbing etc. In doing so it also eliminates 'wastegate creep'.

The Modulator has a third small-bore tube fitted (1) to its top surface that is connected to the Turbo INTAKE downstream of the MAF sensor. This provides an internal solenoid/valve controlled 'escape' route for the Boost Pressure inside the Modulator to be reduced by venting it into the lower pressure turbo intake stream. 

This is the act of Modulation and it ensures that small amounts of the boost pressure are released to reduce the pressure on the Wastegate actuator and thereby delay its opening and thus maintain full boost pressure for longer.

The Modulator is not a sensor of any kind. It does not measure the air pressure passing through it in any way and it's timed operation is governed by the engine ECM that can process signals from the various engine sensors to determine exactly when, how much and how long to open the solenoid. 

It is not a simple 'open and shut' signal either, it is a 'pulse wave modulation' (PWM) that rapidly opens and closes (feathers) the valve to achieve the desired control on the air stream. I can understand the desire to bleed rising pressure above a base level whilst also maintaining pressure at that base level.

On the test runs/data logs, various values have been recorded for the Wastegate Modulator. It should only be operational under boost conditions and has varied from 20% upto its max reading of 40%. At all other times it should read 0%.

Seeing these figures recorded at least shows the ECM and sensors are functioning, but can I really be sure the modulator responds to the command signals?

THE DUTY CYCLE.

That % reading is an expression of the 'duty cycle' meaning the amount of time the valve is open during a given period. The Nanocom data log will record new data every second, so I guess 0% means it is not open at all during that second and allowing Boost pressure to build. 40% means it is open for 40% of that second and allowing the increasing Boost pressure to be diverted away from the actuator thereby maintaining full boost pressure at the manifold for longer...

The ECM in the Td5 has a much higher sampling rate then the Nanocom and can process the signals many hundreds of times per second.

Don't forget that as the turbo spins faster, the boost pressure increases and a point is quickly reached where the turbo will generate too much boost pressure for the engine to handle safely.... Hence we have the whole idea of Wastegate valves and boost Modulators to control the generated boost energy levels.

Performance wise it really does come down to everything being adjusted 'just-right'...

POTENTIAL PROBLEMS.

So, assuming all the rubber hose connections are secure and not leaking and the electrical loom connections/wiring are fine, the only internal faults are to do with the sticking valves. If the valve in the modulator fails to open then the turbo boost pressure will not be modulated and it will flow through to the wastegate actuator. This is the same as on a Defender and can be considered a fail safe condition as it promotes wastegate creep.

Likewise, if the Modulator valve fails to shut fully then the building boost pressure will 'leak' away early and Full Boost may never be achieved.

Depending on how the Wastegate actuator is set up, this could lead to the condition where the Wastegate valve is opened before Full Boost is developed.

In the past I have driven various turbo-charged vehicles including some that 'whistle' as the turbo spools up. This has always been tracked down to a boost pressure leak somewhere, and the engine performance was noticeably down.

That kind of pressure leak is an extreme form of boost modulation. Hx is nowhere near that bad but even a little leak, even not to the atmosphere, would reduce the boost pressure available and be nicely disguised...

TESTING THE MODULATOR.

With the Modulator on the bench, I propose to attach tubing to all 3 connections and submerge the upper two tube ends in water so that when I blow through the remaining tube, air can be seen to emerge from them. If my theory is correct I would expect NO bubbles to emerge from the upper outlet (1) and lots of bubbles from the other outlet (2). This proves the internal link to the wastegate actuator. 

If any bubbles emerge from (1) then it points to an internal leak and a replacement modulator should be purchased..  That's the theory anyway..

REPLACING THE MODULATOR.

As there are no user serviceable parts inside, removal and replacement is the only real option available...

Replacement Modulators are readily available for around £20 from a wide variety of sources.

The photo above is from JGS4X4 and shows all three of the hose connections. The 'Pierburg' brand is the one to go for and on their corporate site I found a comprehensive data sheet about the operation and test data for the Modulator....

The above graphic shows the airflow through the Modulator when the solenoid valve is either 'de-energised' (closed) or 'energised' (modulating) ..

Glad to see my own musings confirmed!

Further reading...

' DISCOTd5.com ' - has a great in depth write-up about the Wastegate Modulator.

Td5 D2 engine - MAP test (3)

Did two more test runs today. Drove the same route as before and the main aim was to get a recording of the max boost available.

Nothing has been done to the engine since last time. The ProVent has still to be connected up and none of the hoses have been cleaned out. Today's journey was to purchase 2 Ltr of white spirit to be used as a cleaning agent for the oil contamination in the intake hoses.

Before the test run began, I ran the output test from the Nanocom to operate the Wastegate modulator. I had hoped to be able to hear the solenoid 'clicking' as advised, but nothing was heard. On the Nanocom screen there was confirmation of the test taking place, but no indication of failure was shown.

On the open road I noticed that 70mph (114km/h) in 5th was at around 2.7k rpm. indicated. The exact figure will be in the data, (2828rpm) and initially I was looking to get the engine rev to 3k. Didn't want to push it in 5th any more then that. I recall being happy with the performance at that speed.

On the 4th test and while going up the on-ramp in 4th, the indicated revs hit 3k which was a lot of fun!

MAX BOOST READINGS : T4/198

MAP - 219.6 k/pa      AAP - 99.08 k/pa
TURBO BOOST  -  120.52 k/pa

This was achieved at 2585 rpm in 4th gear and under load proving the 'max boost' level is dependent on the gearing in use. The condition of overboost can be encountered in all gears.

CONCLUSIONS :

The target MAP reading is 242 k/pa so there is still a long way to go. Assuming the sensors and the Modulator to be functioning correctly that only leaves the wastegate actuator to be 'adjusted'.

Td5 D2 engine - MAP test (2)

Spent a few days number crunching the data logs from the first two test runs and trying to work out how to read, present, understand and interpret the information.

There is a lot of info to extract and I ended up creating a new data log that only shows selected values as a summary. I intend to print-out these new tables and file them for future reference.

I thought of printing out the entire data logs but even on short term tests (15 min) the number of data points accumulated is too much to take in. Data sets are recorded at one second intervals...

RECENT TESTS FOR TURBO BOOST:

Lowest engine rpm - 1949
MAP - 174.77k/pa    AAP  - 100.52k/pa
BOOST - 74.25k/pa  - 10.76psi  -  0.7 bar  

Highest engine rpm - 2548
MAP - 218.8k/pa    AAP -  99.47k/pa
BOOST - 119.33k/pa  - 17.3 psi - 1.19bar

Trying to define if these are 'good' or 'bad' figures is dependant on what set of 'target' figures are chosen.

I am still searching for a definitive set of target boost figures from as many sources as possible. So far trawling the Internet has produced the following...

UNSOLICITED SOURCES:

Boost pressure targets: 'MAP' sensor
242k/pa is full boost.
245k/pa is Overboost

Standard Boost = 15psi - 103.42k/pa
Over-Boost   = 21psi - 144.79k/pa

LR 'Testbook' : Max Boost is 225-230kpa

Most Td5 regulate Boost over 100 kpa. It should start at 120kpa. ECU limp mode is at 130kpa

NANOCOM DOCUMENT : 

MAP reading approx 100kpa at sea level with engine stopped. 100-125kpa with engine at idle.

Boost Generated upto 220kpa at 3k rpm.
Wastegate only operates under 'boost' conditions.

DISCO TD5.COM :

Max value for 'MAP' in stock tunes is 2.42 bar (242kpa) after which the ECU goes 'overboost'

Td5 stock Turbo Boost limit 1.42bar

MAP sensor is a Bosch 0281002205. It reads from 20 up to 250kpa.

It doesn't help when figures are quoted in three different values...  k/pa.... psi....bar. Although 'bar' and 'kpa' values appear to be the same give or take a decimal point.

All are recognized values of pressure and there are thankfully many easy online conversion sites, but all the same it can be frustrating for quick comparisons.

CONCLUSIONS.

It would seem Hx still has more boost to be tweaked.

Another test is required before any adjustments are made to the boost pressure to determine just what the max boost Hx is currently running by taking the engine over 3000rpm.

Upcoming work will see the ProVent breather installed and the removal of the LR depression valve. (The ProVent has its own valve already fitted). Also, I intend to clean the intake pipework and remove and flush-out the Intercooler. Apart from ensuring a cleaner air supply, I do not expect to see any performance gains unless the existing depression valve is faulty.

The Wastegate Modulator can be seen to be getting control signals but I can't be certain it is fully or physically functioning. There is a diagnostic self-test on the Nanocom that will operate the modulator while 'stationery' but maybe removing the modulator to bench test and understand it's function will be better..