Strange Boost Problem...

[EZ Tutty]

Hi guys, for some reason my car has developed an odd boost problem, it 'appears' to be since i removed my N249 and N112 valves compleatly, 4th or 5th gear (not sure about lower gears) i'll put my foot down and get a peak of about 19-20psi on the boost gauge, then it'll instantly drop to about 10psi, but then creep up to 'normal' figures', altho sometimes it will just stay at 10psi and do nothing else (this is mainly in 5th).

i've checked for boost leaks, tweaked the actuator etc, with no success.

I've also done some logs of group 115 & 118, however they don't seem to show the same as my boost gauge, also no fault codes were thrown.

This is 4th gear, 2.5k to 6k rpm (i've cut out the other crap untill the moment it requested more boost)

Wednesday	18	March	2009	15:12:33							
6K0 906 032 AA		1.8L 20VT EU3    01 0002																			
	Group A:	'115				Group B:	'118				Group C:
		RPM	Load	Absolute Pres.	Absolute Pres.		RPM	Temperature	Load	Absolute Pres.	
	TIME					TIME					TIME
Marker	STAMP	 /min	%	 mbar	 mbar	STAMP	 /min	°C	%	 mbar	STAMP
	307.52	2560	67.7	1010	1380	307.12	2520	24	0	1400
	308.32	2760	118.8	1870	1490	307.92	2640	24	1.2	1360
	309.12	3080	168.4	2000	2080	308.72	2920	24	87.1	1780
	309.92	3480	171.4	1920	2500	309.52	3280	24	76.5	2400
	310.72	3800	138.3	1890	2080	310.32	3680	24	55.7	2330
	311.52	4120	144.4	1890	1970	311.12	3960	24	50.6	2030
	312.32	4360	146.6	1860	1970	311.92	4240	25	50.2	1950
	313.12	4640	143.6	1820	1930	312.72	4520	26	49.8	1970
	313.92	4920	139.1	1750	1850	313.52	4800	27	45.9	1890
	314.72	5160	135.3	1710	1780	314.32	5040	27	43.1	1820
	315.52	5360	129.3	1700	1720	315.12	5240	28	37.3	1740
	316.32	5560	133.1	1680	1720	315.92	5480	29	40.4	1670
	317.12	5800	130.8	1660	1680	316.72	5680	30	39.6	1670
	317.92	6000	124.8	1570	1590	317.52	5880	30	34.1	1660

BTW I'm JabbaSport Stage 1 mapped, also have an ECS N75 Race Valve.

Not sure if it's peaking too high (at one point i calculated it to be nearly 22psi )

Could it be going into temporary 'soft' limp mode for a short time? and maybe the times between the log data is too long to see the drop?

Any help would be appriciated

EZT

 

[EZ Tutty]

anyone?

 

[M87NER]

Few people are getting this fault at this moment of time... must be the weather... lol ...

im having the same problem, in 5th gear accelerating up a hill from low revs sometimes doesnt go past 8psi but if it does go past 8psi it keeps losing boost pressure (i.e. climb-drop-climb-drop ect), only does it if its low in the rev range and accelerate hard, need try a different N75 see if that makes a difference... worth a try aswell if ya can borrow one,

 

[EZ Tutty]

i've manage to sort this now seems it was the N75.

Originally the ECS N75 Race Valve worked fine, however when i also did a Full N112/N249 bypass (which from what i've seen also gives a small increase in peak boost). The peak boost was too high for the ECU therefore it was going into soft limp mode.

I Removed the N75 Race Valve and fitted an N75J, and i'm not seeing quiet as much peak boost however it holds 12psi in 5th forever and a day Feels smoother to drive too!

 

[p34ch3y]

im haveing this same prolem...gunna try another n75 valve,im on a std f at the mo mabie this is fooked

 

[cuprachrissy]

sorry but where does the n75 vacuume pipes run too, my car is off the road and replacing all hoses etc. cant remember

 

[turboboy]

search for n75 threads there is a thread with pics of where each hose goes!