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View Full Version : APR stage3 and controlling boost questions



sandnessmj
12-12-2006, 12:52 PM
Well, I figured I'd start a new thread (dear god!) instead of continually jacking old threads and not getting much response. To preface, I have searched, but unfortunately, most of the info I've found isn't specific to BT setups, but rather K03/04's...

So here they are:

1. After hearing some wierd exhaust pulse noises, and then a few weeks later not being able to push over 10psi, I'm thinking I have a waste gate problem. (Doesn't seem to be a leak, because other than lack of power, there don't seem to be any adverse effects while driving (surging, etc.). Also, my boost guage reads a steady 20inHg at idle after a cold start, and 25inHg when no throttle is applied while driving. I also checked the DV, and this seems to be functioning normally.) A few threads I've read suggest that it could be the N75, the wastegate itself, or possibly the rod connecting the wastegate actuator to the wastegate has become disconnected. I won't be able to check these until later on this evening, but in the meantime, how can I test the N75 to see if it's operational? The bracket on mine happens to be covered in rust, which has got me wondering.

2. Can running the car like this cause any damage? I don't really have any choice right now, but I could probably figure something out if need be.

3. Running at <10psi has resulted in excellent gas mileage, which got me thinking...would running MBC setup like this one (see bottom of page "Deluxe 2 stage")http://www.boostvalve.com/pricelist.html be stupid with the APR stage 3? I'd set one for say 10-15psi for daily driving and better mileage, and the other for 22-23psi when I want to get on it. Will driveability suffer?

4. If it does turn out to be the N75 that is causing the issues, should I just look for a stock replacement? Would running a N75J (there are a few in the classifieds) just help me blow up my motor by pushing too much boost? I'm not necessarily looking for more power, here, just the most cost-efficient way to get my car running properly again.

I'm sure there's some other questions I left out - I've been searching for info over the last few days, but none of it has been specific enough...

Thanks in advance for any help.

-Matt

And I'd go on stage3forums for info, except that it takes approx a year to get activated over there...:(

johnnybravoa4
12-12-2006, 01:30 PM
sorry to hear about the problems Matt, i would give you some help but i dont know much about our set-ups yet.. I dont think there is a way to check the N75 with out puting in a new one, you can try un-pluging it and see if that makes a difference, if we lived a bit closer i would say we can swap out ours to save you some cash, I am doing some work on mine this weekend so if you dont mind the drive i have a nice garage at my disposal we can do some testing..

sandnessmj
12-12-2006, 01:37 PM
I might take you up on that offer, Nick - depending on my weekend schedule (the wife's birthday this weekend).

Some of the threads I've found have suggested unplugging the N75 to test, but I'm not sure if that would result in popping my motor...the 28R has the ability to push a lot more than the K03...

johnnybravoa4
12-12-2006, 01:53 PM
well when i unplugged the one on my car it didnt change a thing, but i was running an MBC, i found that my friends 98 had an unpluged n75 when he was having problems with low boost and he was stock, had a boost gauge and was not getting anymore then 4psi, the n75 valve was unplugged we re-connected it and he was back stock boost.. i would unplug it and just roll the throttle untill WOT, and see where the boost goes, it it starts creeping above what you ran normally plug it back in..

in my passat it hit 25 psi a few times so i dought your going to pop anything..

johnnybravoa4
12-12-2006, 01:56 PM
if you need my cell number pm me, im doing a leak-down and a compresion test this weekend also fixing my washer fluid tank and changing out my DV... we have every tool imaginable at this garage, its a fabrication shop..

sandnessmj
12-12-2006, 04:27 PM
if you need my cell number pm me, im doing a leak-down and a compresion test this weekend also fixing my washer fluid tank and changing out my DV... we have every tool imaginable at this garage, its a fabrication shop..

Sounds ideal, man. I pm'ed you.

sandnessmj
12-12-2006, 09:21 PM
Bump for more help...[:D]

white fish
12-13-2006, 12:57 PM
free bump
ps. sandnessmj did you get my PM ??

johnnybravoa4
12-13-2006, 01:12 PM
I also have a vag-com disc and cable, im going to install it on my friends lap-top and pull some logs, might be a good idea for your car as well

sandnessmj
12-14-2006, 01:09 PM
Bump. Still trying to see if a MBC would be compatible (and a good idea) with my setup, and also if the N75J would work.

onemoremile
12-14-2006, 07:30 PM
Although I can't help with the boost problems I do know that you can control your boost with your right foot. Normal acceleration for me is either at 0 boost or 5 psi to 6k rpm or so. It feels nice and smooth and sounds nice that way. I also get 26-28 in town and 33-38 on the open road like this.

sandnessmj
12-14-2006, 08:01 PM
Although I can't help with the boost problems I do know that you can control your boost with your right foot. Normal acceleration for me is either at 0 boost or 5 psi to 6k rpm or so. It feels nice and smooth and sounds nice that way. I also get 26-28 in town and 33-38 on the open road like this.

Yeah, right now the way things are going with my wastegate issues, I don't break 5psi without pretty hard acceleration. I can cruise on the highway at 15-20inHG.

Your fuel economy seems pretty good for a K04 setup...I read some guys' posts saying they get 200 miles to a tank... FWIW, I have about 315 miles on this tank, and right now my needle is midway between 1/4 and 1/2 a tank!

I understand that you can control boost by not slamming the accelerator through the floor all the time, but if I could use a MBC to limit boost to say 10-15lbs tops for daily commuting, it would be cool...cause when I accelerate on the highway, that 28R spools pretty fast...

Seriously, though, I'm just curious about my options. Even just switching between a MBC and the N75 would be interesting.

onemoremile
12-14-2006, 09:20 PM
To be fair, I only average about 7 or 8 mpg on the track...

A bigger turbo should actually have higher mpg with a good tune. A good AFR indicates that the fuel isn't being wasted and there should be less exhaust restriction with a larger turbine wheel, housing, and wastegate. You've got to figure that the turbo really doesn't matter when in vaccuum except for it's presence in the exhaust piping.


As far as real boost control, it shouldn't be difficult to find an electronic boost control that lets you switch between two settings. Scramble boost does just that but it usually has a time limit to the fun.