How To - Fit A Manual Boost Controller (CDTi)

[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.

[Dragrad]

Nice one Jack

Now copied to the How To's

[Jakg]

Bump - a lot of people were after this but I don't think they've seen it

[mrsimon]

Wow, lots of work went into that.

[MalteseMarc]

Nice one Jack! another mod to put on my to do list!

[ramdonice]

i still got the gbe-d from my rover 45 diesel and been meaning to do for a while but needs a new clutch first really but nice guide and the way i would of done it too

[mad]

just to add, you will need more fuel to create more boost, thats probably why your maxing out boost on the controller. gbe-d is a good solid bit of kit but be careful not to add too much lengthen to the wastegate piping, as can create lag and possibility for leaks. Good guide.

[rossocorsa]

interesting that your boost maxed at 21.4 as I found the same situation, when I first fitted my unit it did produce higher boost figures but it was set way too high so I backed it off. Over a wide set of adjustment the max reading was 36.2 which is 21.4 boost coincidence or something specific? would be interesting to know! I suspect that the waste gate and the controller oscillate at max boost, the boost controller opens allowing the pressure to pass the waste gate opens and stays open as boost drops controller closes and so on.... this will stop of course if the controller is set so high that the valve never opens hence why I could see higher figures originally....At the setting that shows 36.2 it did cause the system to cut out at max throttle /low revs until I wound back the setting more (but still showing 36.2 max) obviously there were momentary higher peaks not visible on the obd2 scangauge (which only refreshes at a relatively slow rate) that triggered safety mode on the ecu.
Not a massive improvement over standard but more responsive, I am guessing the lack of waste gate creep is the main benefit(?). Car is still too slow for me though might need to consider a remap (currently have synergy wound up full blast)

[ramdonice]

if using the obd2 port to read boost maybe your maxing out the map sensor, so your getting more boost than 21psi but the map sensor cant read it, maybe worth hooking up a boost gauge to check

[rossocorsa]

Originally Posted by ramdonice

if using the obd2 port to read boost maybe your maxing out the map sensor, so your getting more boost than 21psi but the map sensor cant read it, maybe worth hooking up a boost gauge to check

I think I did see it read higher when I first fitted the controller and it was wound in too far, much more turns than it is now. As the obd 2 display only refreshes about 4 times per second I think very short term spikes in boost prior to the valve opening may not be visible or I might miss them as I am concentrating on the road! Fairly confident I have it right now no cutting out on full throttle at any engine speed.
I should add that being an auto makes it much more difficult to monitor as I can't hold it in a specific gear