Help! persistent boost pressure issue

[Dansh]

Hi Guys, my 2011 DS3 THP 156 has been remapped, and should boost at approximately 1.2 bar according to the tuning guy (a well known tuner, with previous experience on this engine, so i don't doubt him). No matter what i do i can't get my car to boost over 0.7 bar (which is the stock boost it always had)!

I've had it checked for boost leaks and the garage said he found none. While he was at it, he replaced the valve that controls the wastegate actuator (the one under the manifold at the back, not sure what its technical name is) just to make sure it isn't the issue (had one lying around), but no change. I also upgraded the diverter valve to a GFB DV+, thinking it was the known leak at boost issue, but to no avail. I have an MTC intake installed. and other than these two upgrades and the remap, the car is stock.

The car responds very well, and holds boost, just doesn't seem to be able to increase it above stock boost level. What could be the reason i'm stuck at 0.7 bar? maybe the turbo itself?


P.S.
I've gone through all previous posts and none seemed to be of any help hoping one of the experts could save me!

[DS3-NL]

Hey Dansh ,

I am experiencing the same issue, installed a much larger turbo on my car two weeks ago. Went to my local tuner for a new remap and it should be peaking out at 1.4 bar while it stays at 0.9 bar at the moment. Im hoping someone knows how to fix this particular problem

Im planning on changing the MAP sensor, pressure sensor and pressure converter

MAP Sensor: 0 261 230 135 (Bosch)
Pressure Sensor: 0 261 230 134 (Bosch)
Pressure Converter: 7.01777.18.0 (Pierburg)

[DS3-NL]

Hey Dansh ,

I've ordered the parts earlier this morning, hopefully they will be delivered by the end of this week so i can install the new parts this weekend. I will keep you updated about the car whether it is fixed or not

[Dansh]

Thanks! That would be awesome, currently I'm kinda stuck and not sure what to check next. I'd be very interested in hearing how things turned out for you!

[DS3-NL]

Hey Dansh ,

Went to a local garage last weekend and they found out that the current map is not the right one for my car so im getting a custom map made for my car. I dont know if your tuner flashed your car with a wrong map but that could also be your problem.

[Andy@Etuners]

Hi Guys, my 2011 DS3 THP 156 has been remapped, and should boost at approximately 1.2 bar according to the tuning guy (a well known tuner, with previous experience on this engine, so i don't doubt him). No matter what i do i can't get my car to boost over 0.7 bar (which is the stock boost it always had)!

I've had it checked for boost leaks and the garage said he found none. While he was at it, he replaced the valve that controls the wastegate actuator (the one under the manifold at the back, not sure what its technical name is) just to make sure it isn't the issue (had one lying around), but no change. I also upgraded the diverter valve to a GFB DV+, thinking it was the known leak at boost issue, but to no avail. I have an MTC intake installed. and other than these two upgrades and the remap, the car is stock.

The car responds very well, and holds boost, just doesn't seem to be able to increase it above stock boost level. What could be the reason i'm stuck at 0.7 bar? maybe the turbo itself?


P.S.
I've gone through all previous posts and none seemed to be of any help hoping one of the experts could save me!

hi, did u solve this issue?

[Andy@Etuners]

Hi Guys, my 2011 DS3 THP 156 has been remapped, and should boost at approximately 1.2 bar according to the tuning guy (a well known tuner, with previous experience on this engine, so i don't doubt him). No matter what i do i can't get my car to boost over 0.7 bar (which is the stock boost it always had)!

I've had it checked for boost leaks and the garage said he found none. While he was at it, he replaced the valve that controls the wastegate actuator (the one under the manifold at the back, not sure what its technical name is) just to make sure it isn't the issue (had one lying around), but no change. I also upgraded the diverter valve to a GFB DV+, thinking it was the known leak at boost issue, but to no avail. I have an MTC intake installed. and other than these two upgrades and the remap, the car is stock.

The car responds very well, and holds boost, just doesn't seem to be able to increase it above stock boost level. What could be the reason i'm stuck at 0.7 bar? maybe the turbo itself?


P.S.
I've gone through all previous posts and none seemed to be of any help hoping one of the experts could save me!

hi, did u solve this issue?

[DS3-NL]

Hi Andy,

For me this is still a known problem, haven't been able to solve this one yet.

My setup;

DS3 1.6 THP (150 HP)

- JMTC Turbo S42 (https://jmtcperformance.com/super-42-turbocharger/)
- Custom Cold Air Intake (Forge motorsport)
- Forge Blow Off Valve
- Mini Cooper S JCW Diverter Valve (7.05367.05.0)
- Forge Oil Catch Can (boost circuit)
- GT Tuning Oil Catch Can N14 (vacuum circuit)
- Airtec Motorsport Boost Pipe Kit
- Airtec Stage 3 Intercooler Peugeot 207
- Scorpion Decat Downpipe (2.5'')
- Scorpion Cat-Back Exhaust Non-Resonated (2.5")

[Dansh]

hi, did u solve this issue?

Hi Andy, sorry for for the super late respose! I moved to a new place close to work and the car is parked most of the time now. Then covid madness, but I invested in a bit of some needed body work and paint .

Sadly I was never able to solve the boost limit issue, and continue to drive the car on the stock boost level. I really wish I had found a solution, and would absolutely love to get some ideas from the experts here!

[Dansh]

Hey Dansh ,

I am experiencing the same issue, installed a much larger turbo on my car two weeks ago. Went to my local tuner for a new remap and it should be peaking out at 1.4 bar while it stays at 0.9 bar at the moment. Im hoping someone knows how to fix this particular problem

Im planning on changing the MAP sensor, pressure sensor and pressure converter

MAP Sensor: 0 261 230 135 (Bosch)
Pressure Sensor: 0 261 230 134 (Bosch)
Pressure Converter: 7.01777.18.0 (Pierburg)

Hi DS3-NL, were you able to solve the issue?

[DS3-NL]

Hi Dansh ,

Yes after replacing the whole vacuüm circuit which is connected to the pressure converter. Its mounted on a "****" place under the intake manifold. Replaced everything just to be sure i had no leaks anymore, there is even a vacuüm reservoir which is also located under the intake manifold. Be sure to keep the connector from the pressure converter apart since there is a other connector which looks the same as the pressure converter connector. If you want i can supply the original citroën part numbers for that whole circuit.


Cheers,

Mike

[Dansh]

Mike, thanks a lot! I'll try this.
And absolutely, yes please, if you could provide the circuit part numbers involved that would be amazing
Much appreciated,
Dan

[DS3-NL]

Hi Dansh ,

It took me a while to find the exact schematics for the vacüum circuit,since it was some time ago but i've found them

Part #20 - Pipe Air Vent - 1922W1 - https://www.online-teile.com/citroen...W1&language=en
Part #15 - Electro Valve - 1922S2 - https://www.online-teile.com/citroen...S2&language=en
Part #4 - Brake Vac Hose - 4578F8 - https://www.online-teile.com/citroen...F8&language=en
Part #5 - Vacuum Reserve - 454609 - https://www.online-teile.com/citroen...09&language=en

Above are the part numbers and names, i've also added an link to an original Citroën Parts dealer which sells the right parts. For the Electro Valve you could also check Autodoc or other website's which sells them cause they are quite expensive if you buy them direct from them. The original pressure converter is made by Pierburg which has part number: 7.01777.18.0.


Posting an screenshot doesn't seem to work for me, please check the link to the website below for both parts catalogue pictures;

https://ibb.co/C8W6h1c
https://ibb.co/86fhnmy

Cheers,

Mike

[DS3-NL]

Dansh ,

I forgot to add something, it does help if you have a vacüum gauge laying around to measure the vacüum created by the vacüum pump. It should reach 26-30 Inhg (-0.88 bar to -1.02 bar) this is for the vacuum pump outlet to the pressure converter. From the pressure converter to your wastegate it should be around 20-24 Inhg (-0.68 bar to -0.81 bar). You can also test out your wastegate with a vacuüm pump for brake fluid which should close fully at 15 Inhg (-0.51 bar) there should be minor to no play in the wastegate at this amount of vacüum. (Requires to take the downpipe off for propper inspection).

[Dansh]

DS3-NL you are a super star, thank you so much! I might just have chance to fix this vacuum leak now...