2.0TFSI Boost

CSS3

Registered User
Hi all,

After posting months ago, I'm still having no result with my boost issue. I've replaced every single sensor in the engine possible and even a new wiring loom.

This code flags up everytime before the car is even started.

P0234 - Manifold Pressure / Boost Sensor (Overboost Condition) Upper Limit Reached

When driving the car boosts to 1.5 bar and backs of to 1.0 bar. The amount of turbo chatter you can hear is ridiculous, even when driving 20mph people look and think I'm going 100mph. It's now done next to 6,000 miles like this.

When I let of the accelerator at high speeds the engine really judders unless I dip the clutch and the rev clock even jumps up and down.

Any ideas would be much appreciated, I'm hoping it's not gonna be a new turbo!
 

nothingness

Registered User
  • Hoses incorrectly connected, disconnected, blocked or leaking
  • Boost Pressure Control Valve (N75) faulty
  • Boost Pressure Sensor (G31) faulty
  • Turbo Charger stuck/faulty
 

CSS3

Registered User
Already checked all hoses, replaced n75 and map sensor.

We've checked actuator on a ramp previously and it moves freely.
 

CSS3

Registered User
Any other ideas?
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
Has this been like this since you have owned the car? . Has it been mapped?. Have you looked at the boost values in VCDS using the measuring blocks.. Obviously shouldn't be showing any boost as idle or when the engine is off.
Could be a faulty ECU. You might want to consider taking it to somebody who can sort this for you as by the sounds of it you are going to be needing a turbo soon.
 

CSS3

Registered User
Has this been like this since you have owned the car? . Has it been mapped?. Have you looked at the boost values in VCDS using the measuring blocks.. Obviously shouldn't be showing any boost as idle or when the engine is off.
Could be a faulty ECU. You might want to consider taking it to somebody who can sort this for you as by the sounds of it you are going to be needing a turbo soon.

The car always had a boost issue since I purchased it. I knew on the test drive it was lacking power however for the price I didn't want to say no. I've replaced every single engine sensor possible, the wiring loom has also been changed as someone previously cut it all over the place. Everytime I've ever let off the accelerator you could hear the turbo flutter even with the standard filter.

The only thing I find weird is this code shows up on the ECU before the engine is even started. How can it be picking up a boost issue without the turbo doing anything ? I was adamant for so long it's electrical related. The actuator on my turbo moves freely and holds solid boost up to around 1.4 - 1.5 bar then settles around 1.0. I do also note when letting of acceleration the turbo flutters very very loud (quite high pitch) and the revs on the counter bounce up and down around 400rpm.

The only engine modification really is the REVO intake which I fitted a couple months ago.

I have just ordered a recon'd KO3 turbo and have also noticed a new noise my clutch has developed so I'll also be ordering that Monday.

I am now in high hope it's the turbo as the only other thing it could possibly be is the map on the ECU.
 

CSS3

Registered User
New turbo

Hoping this new turbo arrives by Wednesday along with my clutch.

Taking the engine out and cleaning it up, changing gaskets, etc.

I will post up once it's all done and some photos of it all and let you know how she's running :)
 

CSS3

Registered User
Foookin hell that's nice where did u get grill from that stance though

Front bumper came with the grill mate, £660 I think I paid with postage from Xenonz, was £100 to get sprayed also :)
 

CSS3

Registered User
Also fitted 2014 S Line steering wheel

v8kknk.jpg


Here's my shoes too 9.5j

10h0vn6.jpg
 

samuelh_888

Registered User
Will those alloys be too wide for an MOT?
 

CSS3

Registered User
Lovin that steeerin wheel how much how hard was it to fit straight swap??
Steering wheel was a straight swap, however the controls don't work (yet). Cost me £650 in total with the airbag.

Will those alloys be too wide for an MOT?
Yes mate, way too wide. They're 9.5j on stretch tyres and they protrude the arch.
I'm planning on fenders soon so that won't be an issue.

I would say that it's either a faulty ECU or the car has a dodgy map on it. Probably a good idea to get a tuner to look at the map. Maybe load a standard map on the car and see if it is any better.
I was thinking of taking it to a tuner before fitting this new turbo and clutch, would be a ****** to fit these new parts and end up frying a new turbo before it's had any use.
 

CSS3

Registered User
It wont be the turbo if the fault is flagged straight away.

You need to have somebody check the measuring values in VCDS to deduce what is going on. First check what actual boost pressure is reading when engine is idling.

Thank you Rick, I actually have your number a guy called matt who lives on my road gave me your details he has a candy white mk4 golf speaks very highly of you... Any chance I can call for a quick chat tomorrow at all and discuss some options? I'd rather a vag specialist take it from here.
 

CSS3

Registered User
So I have been to DDG Remaps in Rochdale today - the guy spent most of the day on my car logging, etc even cloned my ecu and tried another so we know the ecu isn't the problem.

The map sensor is giving a constant 2170millibar boost reading even when engine is off. Raises up to 2600millibar then throws the overboost condition as it's reached its max limit.

Going to try yet another MAP sensor from TPS tomorrow as I've already replaced the engine wiring loom and we know for sure it's not the ecu.
 

CSS3

Registered User
Forgot to add N75 is also inactive the ecu isn't telling it to do anything.
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
Reading previous posts by yourself it seems that somebody had been messing with the wiring before you bought the car, that is why you replaced the harness.
Have you checked the sensor with a multimeter.This is the wiring for a BWA sensor. part number should be
0261230073
upload_2017-11-9_18-31-0.png

Pin 1 should be the OV connection. Pin 3 should be 5v power for the sensor and pin 4 is the output voltage.
Check you have the correct voltages at pins 1 and 3 . The output voltage of the sensor with no engine running so no boost is usually something like 0.5-1.5v.
If you pull the connector off the MAP sensor you can see the pin designations in the end of the MAP sensor.
 

CSS3

Registered User
Reading previous posts by yourself it seems that somebody had been messing with the wiring before you bought the car, that is why you replaced the harness.
Have you checked the sensor with a multimeter.This is the wiring for a BWA sensor. part number should be
0261230073
View attachment 141148
Pin 1 should be the OV connection. Pin 3 should be 5v power for the sensor and pin 4 is the output voltage.
Check you have the correct voltages at pins 1 and 3 . The output voltage of the sensor with no engine running so no boost is usually something like 0.5-1v.

Your assumption is correct indeed, someone had previously cut plugs all over the place. I'm thinking their reason for that also was this same issue.

Here is the link to the harness that I purchased.
http://www.ebay.co.uk/itm/322630446568

Was removed from a 2.0tfsi manual - BWA engine which is the same as mine - fault code has always stuck.
 

CSS3

Registered User
@desertstorm - After checking the part number you posted I do in fact have the wrong MAP Sensor from what I can see. Euro Car Parts for you I guess.. See what happens tomorrow once I've been to TPS. Thanks a lot for the useful information also.

9,000 miles with this issue, I'm in high hope for a fix tomorrow. I've replaced the MAP sensor around 3 times and i would imagine it's always been wrong.
 
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