FR Tdi intermittant power loss

[phatchoonz1]

Hi,

I've been looking at a 150pd (ARL) FR Tdi, it's got a problem with intermittant power loss, which rectifies itself when the engine is turned off and back on.

The codes i've got out of it are:

17957 - Boost Pressure Regulation Valve (N75): Open or Short to Ground
P1549 - 35-10 - - - Intermittent
18080 - Coolant Fan Control 1: Open or Short to Ground
P1672 - 35-10 - - - Intermittent
17932 - Fuel Pump Relay (J17): Open or Short to Ground
P1524 - 35-10 - - - Intermittent
19461 - Relay for High-Output Preheating of Coolant (J360): Short to Plus
P3005 - 35-00 - -

All of which come back pretty quickly after being cleared.
I've had a search through the forum about these codes, and have found a couple of instances where people have had very similar occurances, but no definitive answer as to what might actually cure it.

The car has recently had the N75 replaced, but still suffers the same problem.

I wondered about the N75 possibly being the issue and have logged 011 for req vs actual performed during a 3rd gear, wide open throttle run.
Am I right in thinking here that the "Duty cycle" is what the N75 is actually sending to the wastegate actuator??

Group A:	011			
	Engine speed	Spec. intake press.	Actual intake press.	D.cycle MAP
TIME	2850-3150	2300-2600	2200-2800	35-80%
STAMP	 /min			 %
0.01	1344	1176	1128	21.9
0.32	1344	1188	1152	23.9
0.66	1386	1560	1140	21.5
1	1407	1752	1236	22.7
1.35	1449	1812	1356	23.5
1.69	1491	1884	1476	27.5
2.03	1554	1944	1632	31.1
2.39	1617	2040	1824	37.9
2.74	1701	2136	2028	44.2
3.1	1785	2220	2220	49.8
3.44	1890	2316	2400	55
3.78	1995	2376	2520	58.6
4.13	2100	2412	2520	58.2
4.47	2226	2460	2496	59.8
4.81	2331	2472	2460	59
5.15	2415	2484	2448	58.2
5.5	2520	2496	2472	59.4
5.85	2625	2496	2484	61.8
6.19	2751	2496	2496	61.8
6.53	2856	2496	2460	62.2
6.88	2961	2496	2424	61.8
7.22	3045	2496	2400	62.2
7.58	3150	2496	2400	62.2
7.92	3255	2496	2400	62.2
8.27	3339	2496	2400	62.6
8.61	3423	2496	2400	63
8.95	3486	2496	2412	63
9.3	3570	2484	2424	63
9.64	3675	2484	2436	64.1
9.99	3738	2472	2436	64.1
10.33	3822	2472	2436	64.9
10.67	3906	2460	2436	65.3
11.02	3675	1080	2172	47.8

I'm quite happy to get some more (different) logs if they're gonna be of any help??

Thanks!

 

[al3xfoster]

Was limp mode triggered at this point?

11.02 3675 1080 2172 47.8

 

[BeartheBruce]

I'd be pulling up a wiring diagram looking to see if there is something in common to the 4 components giving trouble. Bad ground? Flaky +12 connection? Bad relay?

I think it is more likely to be a problem of this nature than a major component failure.