Weird Boost Issue

[Videlov]

Ok so I just saw this problem. Whenever I go into boost in 3rd gear something weird happens. I look at my boost gauge and the boost spikes up to 19-20psi than goes back down to 12-13 than spikes back up to 19-20. It's weird because my foot is on the gas pedal the whole time in the same position. This only happens in 3rd gear... I tried 2nd but it was fine. I have not tried 4-6 gears because I just noticed this.

Video is up
http://www.youtube.com/watch?v=UOa14uhFEuc

Any ideas?

Edit: I don't know if this has anything to do with it... But I have a GIAC 3 Program flash so I was driving on stock mode all of last week, for some reason... I changed it back to pump program on Wednesday and now I'm just noticing this for the 1st time... I don't know if this is relavent but I thought I should share.

[00s4slvr]

i had the same problem a week ago. I beleive its the n75 is taking a crap on you lol. I had that problem except my boost would be at 15-16 spike up to 17-18 then back down to 12-13 then back up to 15-16. I changed the n75 and the problem went away.

[Videlov]

i had the same problem a week ago. I beleive its the n75 is taking a crap on you lol. I had that problem except my boost would be at 15-16 spike up to 17-18 then back down to 12-13 then back up to 15-16. I changed the n75 and the problem went away.

I see, where did you get it from? I'm at work right now and I can't search much cause a lot of sites are blocked... So yeah let me know where you bought it from and how much it will cost me. Thanks

[1FASTB6S4]

they run for 65.00 each and you need two of them.. you can get it from vast tuning i believe

[00s4slvr]

i think your thinking of diverter valves. There is only 1 n75 valve and you can get that from ecs tuning for about 100 shipped i think. THere are the stock n75 and the race n75.

[CONTROL ONE]

they run for 65.00 each and you need two of them.. you can get it from vast tuning i believe

wtf??

is there not only 1? and it's like $125 from ecstuning i believe. they have a 'race' version as well but that gives you problems with a chip.

[1FASTB6S4]

wtf??

is there not only 1? and it's like $125 from ecstuning i believe. they have a 'race' version as well but that gives you problems with a chip.

lol my bad.

[00s4slvr]

yeah theres one. I have the race in my car right now and im gonna do some runs and see if i get any problems with my ecu.

[Videlov]

So it does not matter whether I get the race version or the regular?

Let me know how the test works out 00s4slvr.

[CONTROL ONE]

So it does not matter whether I get the race version or the regular?

Let me know how the test works out 00s4slvr.

if you are chipped, get the regular.

[Videlov]

if you are chipped, get the regular.

Ok.

LOL at ECS the regular one costs more than the race version that's just funny.

[CONTROL ONE]

Ok.

LOL at ECS the regular one costs more than the race version that's just funny.

that's why you should get it at www.genuineaudiparts.com

[Videlov]

Oh I was just pointing that out.

[Videlov]

078 906 283 B

I guess this is the part number.

[00s4slvr]

ok so i did some runs on pump performance mode and my boost goes as follows. i am in second gear going about 40, my boost was holding 15 steady then as it gets towards the redline it tapers down to about 12-14 then when my car shifts it spikes to about 17-19 then holds 15 again and repeats this process throughout the gears.

[Videlov]

And you have GIAC??? Shouldn't it be a bit more aggressive?

[00s4slvr]

i dont know i get mixed reviews about the giac chips boost. Some people say 16-17, while some say 14-15. I dont know, but i have a tip if that makes a difference with the tapering.

[Videlov]

I don't know if tip will make a difference or not. Mine holds 17psi steady and spikes at about 19-20psi which some say is too aggressive for the turbos.

[gointoscott]

Wow spiking to 20psi does seam aggressive to me for K03's But if you want to upgrade to k04's sometime then I guess its not a big deal. But if you want to keep the k03's for as long as possible I'd be nervous spiking that high.

I have the inmotion chip, and the tuner cautions boosting over 17psi because of possible mechanical failure.

I guess to me I feel its safer boosting and holding 15 psi. But thats just my opinion to each their own.

[Videlov]

Well that's the reason why I had switched it back to stock... But stock is just slow now after experiencing stage 1 lol... But yeah my turbos are on their way but that still got some life left in them.

[Paulyworld1432]

I have the same issue currently.. stage 3 though, boost will spike up to 23 then drop to 16 and then up to 23-24 and then back down etc. On a 3rd gear pull it does this about 4 times. I just replaced the N75 and it did not solve the problem... anyone have any ideas?

[will175]

^^what fueling set up are you running?

[Videlov]

Hmmm I have to wait for mine to arrive and than see if that is the problem or not.

[Videlov]

Any updates?
Also, what is the truth...if you are chipped don't get the n75 race and just get the regular?

It came in the mail yesterday, but I have not had the time to change it. I don't have a garage and with this cold it's insane to work on anything outside.

[Paulyworld1432]

FWIW extensive pressure test revealed two leaks causing my boost issues.

1. Small leak in the T connecting wastegate lines off of the N75
2. Pretty large leak in the weld of my RS4 IC from rubbing the fender cut.

Best of luck to finding the cause of your problems!

[s42k5b]

Post your result asap please.
Also, does anyone know whether running the 'race' n75 with a chipped s4 is bad?

I have the race n75 valve on my GIAC chipped gti and it technically made me loose boost versus the stock n75 because I would spike 21 hold 18 and taper to 16 by redline with the stock and with the race n75 it spikes 19 and hold 18 to redline.
Why would it be different with the S4 if both of my cars are GIAC chipped?

Any input wpuld be great, thanks.

I dont think it would be a bad thing

[CONTROL ONE]

Post your result asap please.
Also, does anyone know whether running the 'race' n75 with a chipped s4 is bad?

I have the race n75 valve on my GIAC chipped gti and it technically made me loose boost versus the stock n75 because I would spike 21 hold 18 and taper to 16 by redline with the stock and with the race n75 it spikes 19 and hold 18 to redline.
Why would it be different with the S4 if both of my cars are GIAC chipped?

Any input wpuld be great, thanks.

The GIAC chip is tuned with the Stock N75 valve in mind. Switching to the Race version N75 usually causes more problems than it fixes as boost comes on too soon, gets cut, comes on again, etc.

If you a chipped, especially with the GIAC X chip, you should just get the regular version.

[csre9]

I have the race n75 valve on my GIAC chipped gti and it technically made me loose boost versus the stock n75 because I would spike 21 hold 18 and taper to 16 by redline with the stock and with the race n75 it spikes 19 and hold 18 to redline.
Why would it be different with the S4 if both of my cars are GIAC chipped?

Any input wpuld be great, thanks.

[csre9]

Come on, someone needs to know.
What N75 should I buy if im chipped?
'race' or stock?

[Videlov]

Buy the stock, that's what others said!

[gointoscott]

Stock