More Boost Without N75 (94.5% Duty & Logs)

[Yohan87]

My S3 (1.8T AMK) has a stage 2 custom map and when first remapped it would hit approximately 24psi before tailing off to 22psi which it then held across most of the rev band.

Recently however the car struggles to make anything above 20psi and usually holds 19psi across the range.

Vag-Com shows no faults.

I removed the N75 from the TIP and plugged the tip, left everything else on the N75 connected and just left the end that was in TIP "open" as it were.

Took it for a drive and the car then made 22psi and held it across the range.

Are these the symptoms of a faulty N75 valve?

I shall be performing a boost leak test this weekend to rule that aspect out.

 

[aragorn]

From what you describe, all you've done is created an air leak?

All the boost being bled off by the N75 is supposed to be recirculated, hence its fed back into the tip. By removing it from the TIP, the N75 is still controlling the boost, but the bled-off air is just being dumped.

 

[Yohan87]

Interesting, so why would an air leak cause my car to boost higher?

 

[aragorn]

No idea!

Remember boost is temperature dependant, if its colder outside the ECU requests less boost as it knows the airs denser. Given the recent sharp drop in outside temperatures, its not entirely unexpected that boost request would drop a little.

You'd need to do some logging to find out if the ECU's requesting more boost and isnt getting it, or if its simply requesting less boost because it doesnt want as much.

 

[Yohan87]

That may well be it then.

When logging in vag-com the ECU is only requesting 1.4 bar (approx 20psi).

 

[Welly]

That may well be it then.

When logging in vag-com the ECU is only requesting 1.4 bar (approx 20psi).

Meaning that the turbo is producing exactly what is requested basically?

 

[Yohan87]

Exactly, it's just less than it was producing in October so I automatically assumed the worst.

Here are some logs, hopefully the formatting works.

Wednesday	30	November	2011	19:32:41:62534	VCDS Version: Release 11.11.0	Data version: 20111111
8N0 906 018 H		1.8L R4/5VT 0004
	Group A:	'114				Group B:	'115				Group C:	'031
		Engine Load	Engine Load	Engine Load	Boost Pressure		Engine Speed	Engine Load	Boost Pressure	Boost Pressure		Lambda Control	Lambda Control
	TIME	(specified)	(spec. corrected)	(actual Value)	Control (N75)	TIME	(G28)		(specified)	(actual)	TIME	Bank 1 (actual)	Bank 1 (specified)
Marker	STAMP	%	%	%	%	STAMP	/min	%	mbar	mbar	STAMP
	8.42	97	95.5	22.6	0	7.81	760	21.8	970	980	8.11	0.992	0.992
	9.33	97	95.5	21.8	0	8.72	760	21.8	970	980	9.03	0.992	0.992
	10.23	97	95.5	35.3	0	9.62	760	21.8	970	980	9.92	1	0.992
	11.13	141.4	140.3	51.9	0	10.53	1560	45.9	970	980	10.85	0.922	0.992
	12.05	109	107.5	51.9	0	11.44	1920	54.9	970	1020	11.74	0.984	0.992
	12.95	147.4	146.3	54.9	0	12.34	1600	48.1	970	1040	12.66	1.008	0.992
	13.86	116.5	114.9	19.5	0	13.25	2200	46.6	970	1070	13.56	0.953	0.992
	14.78	118	116.4	53.4	0	14.16	1480	41.4	970	1000	14.46	0.93	0.992
	15.66	130.8	129.9	47.4	0	15.06	1720	51.1	970	1020	15.36	1.016	0.992
	16.58	159.4	158.2	45.1	0	15.97	1960	48.1	970	1040	16.26	0.977	0.992
	17.48	140.6	138.8	15.8	0	16.87	2240	46.6	970	1050	17.18	0.961	0.992
	18.38	116.5	114.9	49.6	0	17.78	1600	15.8	970	1020	18.08	0.977	0.992
	19.29	120.3	119.4	53.4	0	18.68	1600	50.4	970	1010	18.99	0.922	0.992
	20.19	129.3	128.4	55.6	0	19.59	1760	54.9	970	1030	19.91	1.008	0.992
	21.1	137.6	135.8	57.1	0	20.49	1880	56.4	970	1050	20.8	1.008	0.992
	22.01	157.9	156.7	51.9	0	21.4	2040	56.4	970	1080	21.69	0.992	0.992
	22.9	169.9	168.7	49.6	0	22.31	2160	54.9	970	1070	22.61	0.984	0.992
	23.82	170.7	168.7	24.1	0	23.2	2280	48.1	970	1070	23.51	0.977	0.992
	24.71	108.3	107.5	14.3	0	24.11	1920	14.3	970	1040	24.41	0.961	0.984
	25.61	122.6	120.9	29.3	0	25.01	1520	20.3	970	1000	25.32	0.984	0.984
	26.52	122.6	120.9	28.6	0	25.93	1760	28.6	970	990	26.23	0.992	0.992
	27.43	124.1	122.4	27.8	0	26.82	1760	28.6	970	990	27.14	0.992	0.992
	28.33	124.8	123.9	27.8	0	27.74	1760	27.8	970	990	28.03	1.023	0.992
	29.24	125.6	123.9	25.6	0	28.63	1760	26.3	970	990	28.93	1.023	0.992
	30.15	126.3	125.4	25.6	0	29.55	1760	25.6	970	990	29.84	1.016	0.992
	31.05	127.1	125.4	24.1	0	30.45	1800	25.6	970	990	30.75	0.984	0.992
	31.95	127.8	126.9	27.1	0	31.36	1800	24.1	970	990	31.66	0.977	0.992
	32.86	130.8	129.9	57.1	2.7	32.26	1840	35.3	970	990	32.56	0.953	0.992
	33.76	143.6	141.8	93.2	94.5	33.16	1920	78.9	1760	1040	33.47	0.899	0.977
	34.67	169.2	167.2	115.8	94.5	34.06	2080	100.8	2020	1270	34.37	0.961	0.961
	35.58	182.7	180.6	152.6	94.5	34.98	2320	124.1	2290	1560	35.28	0.953	0.953
	36.49	188	186.6	177.4	92.5	35.88	2640	168.4	2410	2090	36.18	0.977	0.945
	37.39	191	189.6	176.7	89.8	36.79	2960	178.9	2430	2300	37.09	0.922	0.938
	38.3	191.7	191	188.7	90.2	37.69	3360	182	2420	2260	37.99	0.93	0.938
	39.2	191.7	191	188.7	91.8	38.6	3720	187.2	2410	2260	38.9	0.93	0.93
	40.11	191.7	191	191.7	94.5	39.51	4080	188.7	2390	2280	39.81	0.906	0.883
	41.01	191.7	191	190.2	93.7	40.41	4440	191.7	2370	2350	40.71	0.875	0.86
	41.92	191.7	191	185.7	94.1	41.31	4800	188	2330	2300	41.62	0.836	0.836
	42.82	191.7	191	180.5	94.5	42.22	5120	184.2	2330	2270	42.52	0.828	0.821
	43.73	191.7	189.6	180.5	94.1	43.12	5400	182	2370	2230	43.44	0.813	0.821
	44.63	189.5	188.1	173.7	94.5	44.03	5640	180.5	2390	2220	44.33	0.821	0.821
	45.54	182.7	180.6	168.4	94.5	44.93	5920	174.4	2360	2170	45.24	0.813	0.821
	46.44	177.4	176.1	168.4	94.5	45.84	6160	171.4	2310	2130	46.14	0.813	0.821
	47.36	170.7	168.7	160.2	93.3	46.75	6360	160.2	2270	2250	47.05	0.813	0.821
	48.25	164.7	162.7	164.7	91	47.65	6560	161.7	2180	2140	47.95	0.813	0.821
	49.17	161.7	159.7	153.4	87.5	48.57	6720	154.9	2100	2160	48.87	0.813	0.821
	50.07	161.7	159.7	145.9	87.5	49.47	6880	152.6	2060	2040	49.77	0.813	0.821
	50.97	191.7	191	12.8	0	50.38	6920	65.4	980	2510	50.67	0.813	0.899
	51.88	191.7	191	12.8	0	51.27	4960	13.5	980	1100	51.57	0.867	0.938
	52.77	136.8	135.8	14.3	0	52.18	3120	13.5	980	1030	52.49	1.991	1.047
	53.69	104.5	103	14.3	0	53.08	1440	13.5	980	1010	53.41	1.811	0.961
	54.58	97	95.5	18	0	53.98	1080	14.3	980	990	54.3	1.016	0.953
	55.5	97	95.5	20.3	0	54.88	880	18.8	980	990	55.18	0.938	0.984
	56.4	130.8	129.9	12	0	55.8	800	20.3	980	990	56.1	0.984	0.992
	57.32	191	189.6	12.8	0	56.7	3240	12	980	990	57.01	1.991	1.047
	58.21	191	189.6	12.8	0	57.61	3120	12.8	980	1000	57.91	1.991	1.047
	59.12	186.5	185.1	13.5	0	58.51	3080	12.8	980	1000	58.81	1.991	1.047
	60.01	119.5	117.9	12.8	0	59.42	2120	14.3	980	1000	59.71	1.991	0.945
	60.92	112	110.4	12.8	0	60.32	1360	14.3	980	1000	60.62	1.211	0.945
	61.82	188	186.6	13.5	0	61.22	2600	11.3	980	990	61.52	1.991	1.047
	62.74	186.5	185.1	12.8	0	62.12	2760	12.8	980	1000	62.44	1.991	1.047

 

[Yohan87]

And here is one with the N75 removed from the TIP.

Wednesday	30	November	2011	20:08:04:62534	VCDS Version: Release 11.11.0	Data version: 20111111
8N0 906 018 H		1.8L R4/5VT 0004
	Group A:	'114				Group B:	'115				Group C:	'031
		Engine Load	Engine Load	Engine Load	Boost Pressure		Engine Speed	Engine Load	Boost Pressure	Boost Pressure		Lambda Control	Lambda Control
	TIME	(specified)	(spec. corrected)	(actual Value)	Control (N75)	TIME	(G28)		(specified)	(actual)	TIME	Bank 1 (actual)	Bank 1 (specified)
Marker	STAMP	%	%	%	%	STAMP	/min	%	mbar	mbar	STAMP
	0.86	97	95.5	25.6	0	0.25	1000	24.1	970	980	0.57	0.977	0.992
	1.77	97	95.5	27.1	0	2.06	800	27.1	970	980	2.37	0.984	0.992
	2.67	97	95.5	28.6	0	2.97	800	28.6	970	980	3.28	1	0.992
	3.57	97	95.5	29.3	0	3.88	760	28.6	970	980	4.18	1.016	0.992
	4.48	97	95.5	38.3	0	4.78	1200	40.6	970	970	5.09	0.945	0.992
	5.39	106	104.5	45.9	0	5.69	1480	45.9	970	990	6	0.969	0.992
	6.29	131.6	129.9	50.4	0	6.6	2120	53.4	970	1010	6.9	0.984	0.992
	7.21	185.7	183.6	61.7	0	7.51	3040	72.2	1130	1100	7.81	0.961	0.992
	8.11	187.2	185.1	14.3	0	8.41	2160	14.3	970	1070	8.71	1.008	0.977
	9.02	166.9	165.7	41.4	0	9.32	2360	41.4	970	1010	9.62	0.906	0.992
	9.91	185	183.6	63.2	6.3	10.22	2760	72.9	1230	1110	10.52	0.961	0.992
	10.82	191.7	189.6	122.6	69.8	11.13	3520	130.8	970	1840	11.43	0.774	0.992
	11.74	188	186.6	14.3	0	12.03	2480	13.5	970	1070	12.32	0.93	1.047
	12.63	182	180.6	12.8	0	12.93	2440	13.5	970	1010	13.23	1.991	1.047
	13.53	177.4	176.1	13.5	0	13.84	2320	13.5	970	990	14.15	1.991	1.047
	14.44	162.4	161.2	12.8	0	14.74	2040	12.8	970	990	15.04	1.991	1.047
	15.35	129.3	128.4	12.8	0	15.65	1760	12.8	970	990	15.95	1.991	1.047
	16.25	115.8	114.9	12.8	0	16.55	1040	18.8	970	980	16.86	1.85	0.945
	17.15	97	95.5	33.8	0	17.46	1040	33.8	970	990	17.76	0.977	0.945
	18.06	99.2	98.5	29.3	0	18.36	1000	27.1	970	990	18.66	0.922	0.992
	18.96	97	95.5	30.1	0	19.28	800	30.1	970	980	19.56	1.008	0.992
	19.88	99.2	98.5	40.6	0	20.17	1480	48.9	970	980	20.48	0.938	0.992
	20.79	115	113.4	48.1	0	21.07	1720	51.1	970	1000	21.37	1.008	0.992
	21.69	168.4	167.2	63.2	1.6	21.99	2560	69.2	1010	1080	22.29	0.984	0.992
	22.59	163.9	162.7	15	0	22.89	1800	26.3	970	1030	23.19	0.953	0.992
	23.5	133.8	132.8	55.6	0	23.8	2040	58.6	970	1050	24.1	0.969	0.992
	24.4	172.9	171.6	69.2	0	24.7	2480	71.4	1150	1140	25	0.969	0.992
	25.31	188	186.6	82.7	0	25.61	3080	113.5	1590	1350	25.91	1.008	0.992
	26.21	191.7	191	181.2	94.5	26.51	4160	191.7	2480	2450	26.84	0.875	0.899
	27.12	191.7	191	186.5	94.5	27.43	5520	16.5	970	1870	27.82	0.938	0.938
	28.13	191.7	189.6	13.5	0	28.43	3280	12.8	970	1050	28.72	1.991	1.047
	29.03	188.7	186.6	13.5	0	29.32	2720	13.5	970	1010	29.64	1.991	1.047
	29.92	185	183.6	12.8	0	30.24	2640	13.5	970	1000	30.54	1.125	0.977
	30.84	184.2	182.1	14.3	0	31.14	2520	15.8	970	990	31.44	0.969	0.992
	31.75	183.5	182.1	16.5	0	32.05	2480	16.5	970	980	32.35	1	0.992
	32.65	182	180.6	14.3	0	32.96	2480	14.3	970	990	33.26	1	0.961
	33.55	179.7	177.6	13.5	0	33.86	2400	13.5	970	980	34.16	0.961	0.953
	34.46	176.7	174.6	15	0	34.76	2360	16.5	970	980	35.06	0.938	0.984
	35.36	175.9	174.6	16.5	0	35.68	2360	16.5	970	980	35.97	1.008	0.992
	36.27	172.2	170.1	14.3	0	36.57	2280	15	970	980	36.86	0.977	0.977
	37.18	171.4	170.1	15	0	37.48	2240	15.8	970	980	37.79	0.992	0.992
	38.09	170.7	168.7	27.8	0	38.39	2240	24.8	970	990	38.67	0.984	0.992
	38.99	169.9	168.7	21.1	0	39.29	2240	19.5	970	990	39.58	1	0.992
	267.49	169.9	168.7	12.8	0	266.89	2280	12.8	970	1000	267.18	1.991	1.047
	268.4	166.2	164.2	13.5	0	267.81	2240	13.5	970	1000	268.1	1.991	1.047
	269.29	156.4	155.2	12.8	0	268.69	2160	12.8	970	1000	269	1.991	1.047
	270.21	148.9	147.8	18	0	269.61	2120	12.8	970	1000	269.93	1.039	0.945
	271.1	146.6	144.8	39.1	0	270.52	2040	40.6	970	990	270.81	0.875	0.945
	272.01	143.6	141.8	39.8	0	271.42	2040	39.8	970	1010	271.72	1.008	0.992
	272.92	141.4	140.3	39.1	0	272.31	2000	38.3	970	1010	272.62	1.008	0.992
	273.83	139.1	137.3	39.8	0	273.23	2000	39.1	970	1010	273.52	1.016	0.992
	274.73	138.3	137.3	41.4	0	274.13	2000	39.1	970	1010	274.43	1	0.992
	275.64	137.6	135.8	36.8	0	275.03	2000	43.6	970	1010	275.34	0.984	0.992
	276.54	137.6	135.8	41.4	0	275.95	1960	36.8	970	1010	276.24	0.984	0.992
	277.44	136.8	135.8	39.8	0	276.84	1960	42.1	970	1010	277.14	0.977	0.992
	278.35	136.8	135.8	37.6	0	277.74	1960	39.1	970	1010	278.06	0.992	0.992
	279.25	103.8	103	21.1	0	278.66	1960	32.3	970	1020	278.97	1	1.047
	280.16	101.5	100	21.1	0	279.55	1120	26.3	970	1000	279.85	1.32	0.992
	281.07	97.7	97	19.5	0	280.46	1080	20.3	970	990	280.76	0.891	0.992
	281.97	97	95.5	20.3	0	281.36	920	18.8	970	990	281.67	0.953	0.992
	282.87	115	113.4	13.5	0	282.27	800	21.1	970	980	282.57	0.992	0.992
	283.78	185	183.6	13.5	0	283.18	2520	12	970	980	283.49	0.984	0.961
	284.69	184.2	182.1	12.8	0	284.09	2640	12.8	970	990	284.38	1.991	1.047
	285.6	183.5	182.1	12.8	0	284.99	2560	12.8	970	990	285.29	1.991	1.047
	286.5	181.2	179.1	12.8	0	285.9	2480	12.8	970	1000	286.2	1.991	1.047
	287.4	173.7	171.6	13.5	0	286.8	2400	12.8	970	1000	287.11	1.991	1.047
	288.3	166.9	165.7	12.8	0	287.71	2240	12.8	970	1000	288	1.991	1.047
	289.21	158.6	156.7	12.8	0	288.61	2200	12.8	970	1000	288.92	1.991	1.047
	290.11	150.4	149.3	12.8	0	289.51	2120	12.8	970	1000	289.81	1.991	1.047
	291.03	142.9	141.8	13.5	0	290.42	2040	12.8	970	1000	290.72	1.991	0.992
	291.93	141.4	140.3	42.1	0	291.32	2000	13.5	970	990	291.63	0.969	0.945
	292.85	157.9	156.7	90.2	94.5	292.24	2040	63.9	1280	1000	292.53	0.93	0.992
	293.75	173.7	171.6	119.5	94.5	293.14	2200	100	2200	1250	293.44	0.961	0.961
	294.65	184.2	182.1	158.6	94.5	294.04	2400	131.6	2360	1600	294.35	0.961	0.953
	295.56	189.5	188.1	182.7	93.3	294.95	2720	175.2	2430	2200	295.25	0.938	0.938
	296.46	191.7	189.6	191.7	89	295.86	3080	185	2460	2400	296.16	0.914	0.938
	297.36	191.7	191	191.7	90.6	296.76	3480	191.7	2460	2350	297.06	0.945	0.93
	298.27	191.7	191	191.7	92.2	297.67	3840	191.7	2440	2400	297.97	0.93	0.914
	299.18	191.7	191	191.7	92.2	298.57	4240	191.7	2410	2390	298.87	0.875	0.875
	300.08	191.7	191	191.7	93.3	299.48	4600	191.7	2380	2400	299.78	0.852	0.844
	300.99	191.7	191	185.7	94.5	300.38	4960	191.7	2350	2290	300.69	0.844	0.828
	301.89	191.7	191	184.2	94.5	301.31	5280	184.2	2380	2270	301.59	0.805	0.821
	302.81	191	189.6	177.4	94.5	302.19	5600	185.7	2390	2250	302.49	0.821	0.821
	303.7	183.5	182.1	174.4	94.5	303.11	5880	175.2	2390	2210	303.42	0.821	0.821
	304.61	176.7	174.6	168.4	94.5	304.01	6120	168.4	2340	2260	304.31	0.821	0.821
	305.51	169.9	168.7	162.4	92.9	304.91	6360	166.9	2270	2170	305.21	0.821	0.821
	306.42	163.9	162.7	157.9	90.6	305.82	6600	160.2	2200	2160	306.13	0.813	0.821
	307.33	161.7	159.7	156.4	86.3	306.72	6760	154.9	2110	2180	307.03	0.805	0.821
	308.23	161.7	159.7	145.1	83.5	307.63	6920	151.1	2060	2140	307.94	0.813	0.821
	309.13	191.7	191	13.5	0	308.54	6520	12.8	970	1740	308.83	0.789	0.914
	310.04	191.7	189.6	12.8	0	309.44	4680	13.5	970	1080	309.74	0.93	1.047
	310.93	121.1	119.4	13.5	0	310.33	2800	14.3	970	1020	310.63	1.991	1.047
	311.84	104.5	103	14.3	0	311.23	1360	13.5	970	1000	311.56	1.523	0.961
	312.74	191	189.6	11.3	0	312.15	1120	16.5	970	990	312.45	0.977	0.961
	313.66	191	189.6	12	0	313.05	5560	11.3	970	990	313.36	1.991	1.047
	314.56	191.7	191	12	0	313.96	5440	12	970	1000	314.26	1.991	1.047
	315.47	191.7	191	12.8	0	314.87	4920	12	970	1020	315.18	1.991	1.047
	316.36	191.7	191	12	0	315.76	4280	12.8	970	1020	316.07	1.991	1.047
	317.27	191.7	191	12.8	0	316.67	3760	12.8	970	1020	316.97	1.991	1.047
	318.17	191.7	191	12.8	0	317.59	3560	12	970	1020	317.88	1.991	1.047
	319.08	191.7	189.6	12.8	0	318.49	3440	12.8	970	1010	318.79	1.991	1.047
	319.99	191.7	189.6	13.5	0	319.39	3360	12.8	970	1010	319.69	1.991	1.047
	320.9	191	189.6	12.8	0	320.29	3280	12.8	970	1010	320.61	1.991	1.047
	321.81	191	189.6	12.8	0	321.2	3200	12.8	970	1010	321.5	1.991	1.047
	322.71	190.2	188.1	12.8	0	322.1	3120	12.8	970	1010	322.41	1.991	1.047
	323.61	190.2	188.1	12.8	0	323	3040	12.8	970	1000	323.31	1.991	1.047
	324.52	188.7	186.6	12.8	0	323.91	2920	12.8	970	1000	324.22	1.991	1.047
	325.43	188	186.6	18	0	324.82	2840	13.5	970	1000	325.12	1.031	0.945
	326.33	187.2	185.1	15	0	325.73	2760	17.3	970	1000	326.03	0.938	0.945
	327.24	185.7	183.6	14.3	0	326.63	2760	15	970	990	326.94	0.945	0.945
	328.14	185	183.6	14.3	0	327.54	2680	14.3	970	990	327.84	0.945	0.945
	329.15	184.2	182.1	15.8	0	328.43	2640	13.5	970	990	328.78	0.953	0.945
	330.06	183.5	182.1	20.3	0	329.44	2600	16.5	970	990	329.77	0.938	0.945

 

[Yohan87]

Those runs were carried out in 4th gear at WOT and sometimes when at full boost I hear fluttering coming from the TIP/Intake and the boost flutters up and down in time with it.

Perhaps the N75 being turned on and off by the ECU?

 

[aragorn]

fluttering under load is not good?

Usually indicates surge, but thats somewhat unlikely on a standard turbo.

Maybe a leak?

Looking at the boost figures, the actual doesnt meet the requested over a lot of the pulls... which could suggest a leak, or a fault with the turbo ie worn out or leaking wastegate.

 

[Yohan87]

It's a standard turbo (K04-023) and the engine/turbo has probably only covered around 30,000.

There is a fair bit of timing pull and on one occassion I even recorded 10's on one cylinder so I suspect a boost leak.

Hopefully the boost leak test will reveal all.

 

[badger5]

10's!

yowzer.. be safe dude..

 

[Yohan87]

10's!

yowzer.. be safe dude..

I know :-(

It never used to do that until my boost went missing.

I am just hoping there is a boost leak somewhere, which is causing knock, ECU is then pulling everything back and asking for less boost as a result?

Or am I talking crap.

 

[Rosso TT]

I have experienced something similar.
Had a smoke test carried out about two months ago and discovered a leak on the charge pipe and on the DP, fixes those and my boost went down from 22 psi to 18, did some logs and found out that the actual boost takes a while to match requested at about 4300 rpm, so i've got a new n 75 and boost returned.
Went with the car club two weeks ago for a spirited drive and the hose on the end of the charge pipe popped off, refitted again and now boost is at 18 psi.
It's like with boost leaks my turbo spools quiker and harder!

 

[camscockle20vT]

I have experienced something similar.
Had a smoke test carried out about two months ago and discovered a leak on the charge pipe and on the DP, fixes those and my boost went down from 22 psi to 18, did some logs and found out that the actual boost takes a while to match requested at about 4300 rpm, so i've got a new n 75 and boost returned.
Went with the car club two weeks ago for a spirited drive and the hose on the end of the charge pipe popped off, refitted again and now boost is at 18 psi.
It's like with boost leaks my turbo spools quiker and harder!

Yup its due to the air being able to escape quicker, with less resistance. Just read beachbuggys ko4 hybrid thread

 

[Yohan87]

I just read that as well.

In the "flutter video" in that thread I sometimes get the same thing as what happens at the end of the video.

 

[Westy]

It's like with boost leaks my turbo spools quiker and harder!

The turbo will work harder to match boost if the map sensor is not getting the airflow it's expecting due to a leak. This is also why pressure drop across intercoolers is an important factor.

 

[Yohan87]

What would cause the ECU to not request as much boost?

 

[badger5]

its load request would have been met

 

[Yohan87]

So to make sure I understand.

If there is a leak, it will hit it's load request much earlier as it's working harder against the leak?

 

[superkarl]

surely it would hit load request later?

 

[Yohan87]

That could also work I guess.

I'll test for boost leaks first and then take it from there.

Why is the N75 duty 94.5 and not 100?

 

[badger5]

its the limit its set to... varies slightly between cars/ecu's

 

[Rosso TT]

Thanks for the info guys, i might need a new bigger mofo intercooler then.
Always suspected mine is a bit restrictive and hot.

 

[Westy]

Thanks for the info guys, i might need a new bigger mofo intercooler then.
Always suspected mine is a bit restrictive and hot.

What cooler do you have a t present? I tried 3 different FMIC setups and now run the huge toyosport one, which is very good.

 

[Rosso TT]

At present i have a tube and fin style cooler 450x230x55 63 inlet/outlet.
I'm thinking of getting same style core but wider and thicker and not necessary taller.
Today i had the timing settins turned down to 1, starting to get hot down here.

 

[Yohan87]

Well today I tested for boost leaks and it appears there are none so the next step is to try another N75 valve. My current version is an F so would a replacement F be the best option?

 

[Yohan87]

its the limit its set to... varies slightly between cars/ecu's

Would setting the limit higher help compensate for a dodgy valve?

 

[badger5]

no... duty cycle is duty cycle.. max'd out is what it is doing.

 

[Yohan87]

Ok.

So if I've no boost leaks then is it common for these N75's to just stop working properly and cause slightly lower boost?

 

[badger5]

thats Not what I have said

 

[Yohan87]

Bill, you've lost me...

 

[Yohan87]

Well this evening I tried a wee test of the N75 valve. Firstly tried to suck air through the longest pipe (TIP side) but couldn't, no air passing through. Also tried to blow air through it and couldn't either. Out of interest sake I sucked/blew the bottom of the N75 valve (from charge pipe) and had the same result, no air passing either direction. However, my MAP sensor is another story.... I went to check the plug was in properly and noticed a crack on it and there is a lot of flex on the plug I took a video so hopefully it shows what I mean. Could this be the reason I can only make 17psi boost instead of my usual 24psi spike/22psi held across the range? The car is showing no fault codes.

 

[badger5]

you should be able to blow thru the centre (boot in) port of the n75 and it should exit the long (tip) port.
yours sounds blocked which is'nt good.. but this should create uncontrolled boost if when you blow into the ports nothing comes out..?

 

[Yohan87]

Thanks Bill.

I definitely can't blow through the "boost in" port, nothing comes out. Obviously I can't blow air through at the pressure a turbo does but still doesn't sound right if something should be exiting the TIP port.

Could it be that the valve is sticky and the turbo can push some air through but not enough to for me to reach max boost?

 

[badger5]

normally you can easily blow thru them as a test, so summats amiss 4 sure

 

[Yohan87]

Ok Bill, a friend is popping past with his LCR also with an F valve so I will swap them over and see what happens.

 

[Yohan87]

Morning Bill,

I tried an N75F valve from a friends AUM last night and all my lost boost was restored

Obviously I can't keep his so will be buying a new one and the dealer advises that the E valve has superceded the F.

Are the characteristics exactly the same?

Thanks

 

[Broken Byzan]

Your dealer is wrong, the F valve supersedes the C valve and is a later revision than an E anyway.

 

[Yohan87]

I don't think they are, from what I've read and the parts people I've called the E has superceded the F. I believe it went C -> F -> E. Alphabetically it doesn't make sense but the part numbers are: - F = 058 906 283 F E = 06A 906 283 E Either way, I bought a new E valve from them and replaced my valve with it and normal service is resumed and the car is back to how it was. Thanks to everyone who replied (especially Bill).