Sharan TDi boost problem

[phatchoonz1]

We've got a 2001 VW sharan 130 TDi in at work at the moment suffering badly from boost problems. It's basically not boosting at all, then has the odd spike where it boosts momentarily.

Any help would be much appreciated!!

It has this fault code stored:
VAG-COM Version: Release 311.2-N

Control Module Part Number: 038 906 019 FC
Component and/or Version: 1,9l R4 EDC 0001SG 1455
Software Coding: 00002
Work Shop Code: WSC 00020
Additional Info: WVWZZZ7MZ2V013043 VWZ1Z0A1668664
1 Fault Found:
17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-00 - -


The turbo itself has been checked out by a turbo specialist and we've tried replacing two pressure sensors so far and the MAF sensor.

Today I took some logs of 2nd and 3rd gear pulls with my VAG COM as it's still not right.

I've logged blocks 3 & 11 on separate runs and produced these results (sorry haven't figured the code for the best way to display them on here yet):


Group A: '011
Engine speed Spec. intake press. Actual intake press. D.cycle MAP
TIME 2850-3150 2000-2150 2000-2200 40-95%
MARKER STAMP /min mbar mbar %
6.19 1470 1468.8 2539.8 94
6.71 1554 1417.8 2539.8 94.4
7.21 1575 1397.4 2539.8 94.4
7.64 1575 1295.4 2539.8 94.4
8.06 1596 1264.8 2539.8 94.4
8.51 1617 1275 2539.8 94.4
8.94 1659 1785 2539.8 94.4
9.38 1680 2182.8 2539.8 63.8
9.82 1743 2244 2539.8 63
10.27 1806 2254.2 2539.8 64.5
10.71 1869 2274.6 2539.8 66.1
11.14 1932 2284.8 2539.8 66.9
11.58 2016 2284.8 2539.8 68.9
12.02 2058 2284.8 2539.8 70.9
12.52 2142 2274.6 2539.8 73.3
13.03 2205 2254.2 2539.8 76.1
13.55 2289 2233.8 2539.8 82.1
13.95 2352 2233.8 2539.8 82.5
14.39 2394 2223.6 2539.8 85.7
14.83 2457 2213.4 2539.8 91.6
15.27 2520 2203.2 2539.8 93.2
15.7 2604 2193 1397.4 19.9
16.09 2709 2182.8 1591.2 60.2
16.53 2856 2172.6 2509.2 94.4
16.97 2982 2152.2 2539.8 94.4
17.41 3108 2142 2458.2 94.4
17.85 3234 2131.8 2539.8 94.4
18.31 3339 2121.6 2539.8 94.4
18.87 3465 2121.6 2539.8 94.4
19.36 3633 2111.4 2539.8 84.1
19.78 3759 2111.4 2539.8 94.4
20.22 3885 2111.4 2539.8 94
20.66 4053 2091 2539.8 94.4
21.1 4200 2029.8 1907.4 86.5
21.54 4347 1999.2 1866.6 80.5
21.98 4473 1989 2499 94.4
22.42 3738 1060.8 1723.8 43

It seems to me that the actual pressure reading is incorrect as it always keeps coming back to 2539.8 no matter what the ECU is requesting, other than a couple of odd spikes.

If it would help to get some more logs of any other data just let me know!

Thanks for taking the time to look!

Martin

 

[stoneyfordNI]

vanes on the turbo could be sticking ,
EDIT

http://www.seatcupra.net/forums/showthread.php?t=70568&highlight=10k

http://www.seatcupra.net/forums/showthread.php?t=94652&highlight=boost

 

[phatchoonz1]

hmmm, we'd heard of that, but as I say, the turbo has been removed from the vehicle, sent to a specialist, come back, been refitted and still has exactly the same problem!

 

[stoneyfordNI]

have u tried swapping n75s , does the sharan use an actual valve or a black box as in the ibiza

 

[phatchoonz1]

I haven't actually taken a look at it myself yet, i've just got involved with it this afternoon as our mechanics are now struggling and i've got VAG COM for my leon! Any ideas where the N75 might be located in the engine bay of a sharan?
I've been told that the pressure sensors replaced by our guys are fitted to the bulkhead right at the back of the engine bay, there's two that look almost identical side by side.

 

[stoneyfordNI]

trace the pipe from the actuator , itll either go to a black box , or a wee valve with 3 hoses and a plug

 

[phatchoonz1]

Cheers for your help, shall take another look tommorow and let you know what happens!

 

[cheshire cat]

I haven't actually taken a look at it myself yet, i've just got involved with it this afternoon as our mechanics are now struggling and i've got VAG COM for my leon! Any ideas where the N75 might be located in the engine bay of a sharan?
I've been told that the pressure sensors replaced by our guys are fitted to the bulkhead right at the back of the engine bay, there's two that look almost identical side by side.

are you sure the "pressure sensors" are not the N75 and it's mate which is for the EGR, they may have been repiped the wrong way round

 

[phatchoonz1]

Could anyone confirm what the part number for the N75 on this vehicle? Its an AUY engine code if that's any help.

I will post this in the parts section also.

 

[phatchoonz1]

Figured it out at last! Of course, so simple when you know what it is!

MAP sensor faulty....

Thanks for everyones help though!