help - on going boost problems

[j2da]

After having my car logged and checked with vagcom i realized there are some boost issues. i have the GIAC 93 chip.

I logged a 3rd gear pull all the way to redline - (i will try to get graphs and readings posted) - the result was: it hit peak boost ~20psi , then substantially tapered off, a lot more than it should. the MAF readings are also lower than they should be.

17964/P1556 - Charge Pressure Control: Negative Deviation is also being thrown, but with no CEL. Symptoms: loss of power, limp mode

When i do a pull past 5k it will put it into limp mode (wont go over 7psi until i restart the car).

i checked the code and the causes said boost leak, so i pressure tested up to 20psi and didnt find any leaks. but when pressure testing i heard a bubbling sound inside the block itself. i blocked the PCV valve before testing too, so there shouldnt be any blowby. whats this sound?

another cause is said to be the n75 but i replaced mine with the ECS n75 a few months ago, so that shouldnt be the problem either.

thanks to anyone that helps ahead of time, and im going to be getting the exact MAF readings and boost logs as soon as i can.

[j2da]

974 views and no ideas?

[j2da]

i did some research and found this: http://forums.vwvortex.com/zerothread?id=1245887

thats pretty much the exact problem i am having. the only thing is, i already replaced my n75 with the ecs "race" valve. has anyone had problems with running the ecs n75 valve with giac before?

[FourBlackRings]

how many pounds of boost should run on the 93 giac chip cause i have the same one but when i pound it the needle jumps between 10 and 14 pounds like its having a fucking seizure and i found a very small leak but its under the intake manifold but you may want to check there just do a air leak test and spray some soapy water under the manifold on the hoses.

[j2da]

yeah i did a pressure test and no leaks. i do not have a vacuum leak, i have pressure tested a couple times up to at least 20psi. no leak

with the giac, i am getting about 19-20psi. i have the vdo gauge and its pretty accurate within a psi or two. i thikn the n75 should have added a pound or two too. thats just a spike tho, i cant hold a lot of boost if i step on it for more than 10 seconds, and then it goes into limp mode. when i do hold it, its a few pounds under what it should be.

[j2da]

so i got the logs

my maf readings dont go above 132 g/s. with the chip i should be seeing 160. these are the numbers
2920 31.28
3080 75.31
3400 103.94
3760 110.47
4080 118.17
4400 125.19
4720 127.89
5040 131.69
5320 132.97
5560 128.08
5800 130.36
6080 132.11
6320 134.14
6520 131.89
6760 134.19

my timing is also off big time. what could this mean?
3080 13.5
3400 8.3
3760 6
4080 9.8
4400 6.8
4720 9
5040 9.8
5320 9.8
5560 12.8
5800 13.5
6080 11.3
6320 12
6520 18.8
6760 15.8

i will be logging the boost duty cycle signal as soon as i can to see if the n75 is my problem.

[j2da]

these are the boost readings i am getting too


RPM -Requested -Actual
2880 980 1220
3000 2140 1240
3280 2170 2090
3600 2190 2210
3960 2200 2190
4320 2180 2150
4640 2150 2070
4960 2140 1970
5200 2130 1870
5480 2080 1800
5720 2090 1660
5960 2040 1640
6200 1990 1640
6480 1950 1610
6720 1900 1590

[milehighpilot]

you have the old n75? cause if you do swap it out. if you search the vw forums you'll find that alot of people who put in a different n75 get all kinds of different results. and yes some people have issues depending on the year and model of their car with the ecs n75. they even dabbled to suggest that an h valve will work differently than a j valve,(j i think is peak and h is long term but im not sure anymore) there is a lot of stuff on it.

[j2da]

i dont have the old valve, but im going to swap it out with a buddies of mine and see how it goes. ill also be checking the duty cycle signal to see if its clamped.