How To - Fit A Manual Boost Controller (CDTi)

[lightningmark]

Originally Posted by rossocorsa

I should add that being an auto makes it much more difficult to monitor as I can't hold it in a specific gear

Why not??????

[rossocorsa]

Originally Posted by lightningmark

Why not??????

The jatco box only allows you to restrict the highest gear for instance you select 3 it will work as an auto box using 1,2 and 3 gear only. Pretty annoying tbh hate it although the box is otherwise very good

[rossocorsa]

Originally Posted by Jakg

If you want to up the turbo boost on your CDTi, without doing the "spring mod", heres how...

First of all, Ron made a great PDF about what this does and how to do it here - http://tuning-diesels.com/Synergy/75...adjustment.pdf

However, heres a quick how-to with some pictures...










You'll need:

A boost control valve - I used the GBE D-EVO - other makes are available (and cheaper) but this comes Ron-recommended, and is "specifically designed" for the pressures diesels run at, whereas petrol ones lose a lot of adjustability at 20-ish PSI as they are designed for ~10 at most. If you do buy a GBE one, this is worth reading - http://www.gb-ent.com/downloads/BCVInstructions.pdf



1m of Silicon Vacuum Hose - I used 4mm. In hindsight, maybe a little too small. But with some persuasion it went on.

1 hose connector - I used a 4mm one, again use whatever goes with your hose.



Some cable ties

Some way of reading your current boost pressure (either a boost gauge, ELM 327 diagnostic tool or something like a Scangauge)

And if you get a GBE D-EVO you'll also need a 5/8 spanner - the locknut comes all the way tightened and like this you can't turn the boost up or down at all!












Now for fitting...

Jack the car up, and put it on axle stands. Previously, I've seen this referred to as a "ramp" job - it'd definitely be easier this way, and access isn't brilliant, but you can still easily do it with just axle stands.



Haynes recommends putting them under the jacking points, but I found that the car was too low / the jack wouldn't go high enough so that just wasn't possible. Instead I put them under the front subframe.





Lower the car onto the axle stands and make sure it's secure BEFORE you get under it.

Now, remove the undertray - you'll find the screws (crosshead) are probably rusty and easy to destroy the heads so be careful. I've marked the locations of all the screws (although your car might not have as many as it should...)



You will now see this



Follow the exhaust up into the engine and you will find the turbo, stuck to the side of the manifold. You will need to disconnect the pipe highlighted in red. I found it easiest to remove it from the inlet end (i.e. the top bit)



To remove, squeeze the little tabs together and wiggle the clip down the hose. The hose should then just pull off (with a little persuasion)



Leaving you with this



Now get your boost controller ready.



The INLET goes to the TURBO, the OUTLET goes to the WASTEGATE. Don't get them mixed up!

I started off by taking my vacuum hose and putting each end on the valve. 4mm was slightly too small, and I couldn't get it all the way up. Having said that, it still proved VERY difficult to get off so it was probably fine. But I found it helped to leave the ends of the hose in boiling water to get them a little more pliable. Then with some force and a little twisting I got them the whole way up the valve. I also re-inforced the joints with cable-ties, which in hindsight was probably pointless.



Now get back under the car and take the hose you've taken off the turbo, and put in the connector - then slide the clip back up to keep it secure.



Now you need to find a suitable place to mount the boost controller. It needs to be as close to the to the turbo as possible, as the longer the tubes, the more chance you have of having a boost spike. A boost spike it the opposite of turbo lag - the pressure temporarily rises higher than it's meant to, while the pressure takes it's time to reach the valve, which would eventually switch the wastegate. Either you run the risk of the spike being too high pressure and hurting the engine or causing boost cut-off, or you have to run much lower "normal" boost to accommodate the spike.

Unfortunately, the turbo is in a very inaccessible location, so you have to mount the control valve somewhere else. You need to consider the distance from the turbo, but also accessibility to adjust if needs be - and have the ability to get a spanner there to do up the locknut.

I chose to use the bulkhead, cable-tied to a plastic nut that holds some of the deadening in place, under the upside-down "L" shaped space where traction control would be fitted.





Now feed the hoses back down to the turbo, making sure you can correctly identify which one goes to which side!

You now need to connect the hoses to the turbo. Connect the OUTLET to the WASTEGATE, which will be the "loose" hose you've put the connector on. I chose to cable-tie the vacuum hose side for security - but you don't need to. Cut the hose as short as you can, without the risk of it getting bent shut or breaking. Now connect the INLET to the TURBO, where you originally unplugged the hose - slide it all the way over and it should be fine. Again, I used a cable tie to secure - optional.



Top red line is the wastegate connection, bottom is the turbo one.

Close-up



I also chose to cable-tie the hoses out of the way of the A/C pipes



Now you've done (the installation bit...)

Personally I'd leave the undertray off (just in case you've got a leak or something!) and go for a drive.










Testing

First of all - I would recommend starting with it turned off. The more you UNDO the dial on the top, the less boost you are asking to the valve to control. If the dial on the top is set less than the cars standard boost levels, the car will drive as normal (perhaps with slightly less wastegate creep). It's only once you go over the standard settings, where your asking the controller to hold the turbo at a higher difference, you'll actually be able to see a difference. If the dial won't turn, make sure you undo the locknut just underneath.

Before you start the engine, check your boost pressure. If you are monitor the MAP sensor (Manifold Absolute Pressure), you should get ~14.8 PSI (100 KPA / 1 Bar). You will need to subtract this from any readings to work out how much boost the turbo is adding. If your using a boost gauge, they normally work on relative pressure - so should be 0 with the engine off.

Now (with the valve turned off), see how much boost your getting to start off with. Run through a gear from ~1500 RPM to ~4000 RPM (peak boost should be 2-3k RPM) (I used 3rd / 4th for convenience).

Standard boost pressure is 17 / 20 PSI (i've seen both mentioned - mine was 19.5 PSI) - if you get significantly less than this, you probably have a boost leak somewhere (when my intercooler came loose, it would hit ~8 PSI at most!) which you WILL need to fix before you can even think about adding more boost.

Now slowly do up the dial on the boost controller, I would say 1 turn at a time, and keep doing quick runs to keep an eye on the pressure. You should find a setting where you can start to feel the controller take over as your getting more and more boost. Once you are getting close to your limit, you may wish to go for 1/2 or even 1/4 turns.

What you want to go for is up to you - but boost cut is at 23-24 PSI and you definitely don't want that to happen. I accept no responsibility for you pushing too high and killing your engine, gearbox, clutch etc!

I found that for some reason the maximum pressure I could get was 21.4 PSI, so I set the controller at the lowest setting required to acheive this, and tightened the locknut.






As an aside - it MAY be a better idea to totally replace the OE line rather than adding the extra lines (i.e. rather than adding a connector to the wastegate hose, simply unclip it at both ends and use one long run from the wastegate to the controller. I didn't do this, as I didn't have enough hose, and access is rather difficult with the drivetrain in the way.

You could also use the bulkhead position for configuring the controller, and then move it back next to the turbo to keep the lines as short as possible - but it would make future adjustment very difficult.


Disclaimer:
You are responsible for any work or modifications carried out on your car and you undertake any such work at your own risk.
The 75 and ZT Owners Club nor the original author of this How-To can be held liable for anything that may happen as a result
of you following this How-To.

found an answer on the boost reading issue, obd2 will not show pressure above 2.5 bar which just happens to be about 36.2PSI ........I presume the MAP sensor reads higher and the ecu can see this which would explain why it appears possible to hit the boost over pressure cut out despite seeing 'only' 21.4 of boost

[rossocorsa]

Found that torque can use MAF for boost figs so I've set it that way and will see what it comes up with, however as I have synergy plus pierburg I have my doubts that it will be accurate. Will report back tomorrow

[rossocorsa]

Originally Posted by rossocorsa

Found that torque can use MAF for boost figs so I've set it that way and will see what it comes up with, however as I have synergy plus pierburg I have my doubts that it will be accurate. Will report back tomorrow

tried the MAF method of taking the boost reading but tbh it didn't seem to give believable figures so back to MAP despite its limitations, probably fair to say that if you hit the OBD2 reading limit your boost is probably to high anyway

[nickW]

my boost is running at around 18.5psi, would raising it 21psi make that much difference to the way it drives?

[Jakg]

Originally Posted by rossocorsa

probably fair to say that if you hit the OBD2 reading limit your boost is probably to high anyway

Mines been running at 24 PSI for nearly 2 years and 30k miles and it's not exploded yet.

[nickW]

another question, my psi reaches 18.5 first then back off slightly, is this normal.
with the boost controller fitted does it hold the boost at the amount it first hits

[Jakg]

Originally Posted by nickW

another question, my psi reaches 18.5 first then back off slightly, is this normal.
with the boost controller fitted does it hold the boost at the amount it first hits

Does it spike up a little higher, then hold at the lower value? If so - it's boost creep.

Does it go to the top value, and gradually decrease as the RPM increases? If so - that's normal, it's a small turbo.

[nickW]

yes it spikes then holds lower, so boost creep yes,
would this be due to a weak spring on the wastegate.
am i correct in thinking that by fitting a manual boost controller i can get it to hold the higher value