I've been researching my issues for 2 days now, however with all the different situations found, I feel more confident posting my exact situation in a new thread, thus please don't feel as if I haven't tried digging before making a new thread....

Software-Speedtuning K04 for stock injectors and 5BAR (similar to the GIAC mild program according to Oliver with ST)

Turbo-Buy Auto Parts K04-15 installed 4 days ago

Supporting mods-2.5" exhaust, 3" test pipe, N75J 2 years old, 225TT DV 3 months old, 5BAR FPR

Situation:

I decided to use Speedtunings K04 software on stock injectors and 5BAR while still on the stock k03, ST said I wouldn't have any issues as long as I don't beat the **** out of it. I had the software on the K03 and stock 4BAR for about 3 months without any issues, no codes, etc. I was boosting anywhere between 15-21PSI and the power was great, like I said no issues and no codes. I was actually shocked I didn't throw any Fuel/Air related codes while running the 4BAR and K04 software, but maybe because it was running the K03 with less air flow that's why? Anyway, I did check the fuel trim values via Vag-Com on this setup and everything was good, not lean nor rich...now onto the K04 upgrade issues as of current.

After 3 months of running the K04 software on the K03, I decided to purchase a cheaper K04 to match the software, as well as a 5BAR......

I just had the BuyAutoParts K04 and the 5BAR installed 4 days ago....and right after my mechanic finished the installation/swap of turbo and FPR.....OVERBOOST like crazy! I'm throwing codes for "maxed out MAF" and "overboost limit exceeded." The boost is 25+ to 30+ since my boost gauge only goes to 30PSI. The power is far more than what I should be having on just a K04, it's fun however extremely dangerous and annoying (i.e. no driveability). It'll boost straight to 25psi in first or second gear, but no boost bleeding...just stuck there. In 3rd/4th/5th gears the boost jumps even at 1/2 throttle to 25psi +....and this is when the turbo/ecu cuts out power until I let off the gas. Of course I'm not driving the vehicle after finding all of this out, no way it's safe for the motor, turbo, etc....

So, this week my mechanic will be testing the N75 (although it worked perfect before installing the turbo), testing the DV (although it worked perfect before installing the turbo), checking for boost leaks (no issues found 2 weeks prior to installing the K04 per testing-vacuum is 21hg in idle as well).....

With everything working correctly with the software, 4BAR, and K03 for months before the swap, I'm guessing it's something to do with the turbo (Cheap K04 causing problems wouldn't shock me at this point)......

My mechanic thinks there's something not right with the wastegate, and we'll be testing/adjusting that this week. He does know how to test/adjust the wastegate, but I AM not too sure how all of this works, and would like to know if someone can shed light on the subject? Is the wastegate and actuator the same part(s)? Because the turbo is a chinese knockoff, is it possible that the wastegate could be bad? OR, just needs to be adjusted?

Because the N75J, DV, and software didn't give me any problems for months prior to installing the K04 turbo, doesn't it seem logical that the issue lies withing the turbo itself? I'm going to call BuyAutoParts tomorrow and ask about the wastegate issues, and since the turbo is warrantied for one year, there's no issue with having the send me out a new one, however I'd just hate to get another Chinese replacement and have the same issues. They do sell BW's but for 3 times the price. I'd be willing to pay the money after dealing with the headache, but at this point am just hoping something on the turbo I already have can be adjusted to lower the boost and alleviate the issue(s).

My mechanic is family and I don't get charged labor, and hence is the reason I decided to go with a cheap K04 (also because the vehicle has 250K miles). I have been in contact with a couple other members that run the BuyAutoParts K04 on their A4's without any issues (some of them over 1+ year). I did call Speedtuning and asked them about the software, however Oliver said since there wasn't any issues running it on the K03, and all of the problems with overboost occurred after the K04 install, it's more than likely the turbo and not the software, seems to make sense right?

If anyone has had similar problems with their K04, and were able to resolve the issue with adjusting the wastegate/actuator on the turbo, please help me out! I appreciate the time spent reading this post ahead of time! Since the boost isn't bleeding off, overboosting, and no issues with the N75/DV, software prior to the K04 install, I'm almost sold on the issue being the turbo itself, anyone disagree?

 

Two things, disconnect the battery for a few minutes and reconnect so the ecu will reset (then do a tba obviously). After that you should install a mbc in parallel to your n75, almost all people running larger than stock turbos use the mbc to limit over boosting and boost spikes. I don't think this is a wastegate issue, but if you want to be sure run a line directly from the compressor housing nipple to the wastegate nipple (completely bypassing the n75). When you drive you shouldn't get over ~5-7 psi

 

Thanks for the reply. Honestly, I don't want to run a MBC unless "absolutely necessary." Thing is, I've come across K04 owners that do just fine without one as well....

Thing is, because the boost isn't bleeding, wouldn't that suggest something is stuck with the wastegate? To me, that symptom says a lot, but obviously I'm not "sure" otherwise I wouldn't be seeking advice from others. Like I mentioned in my original post, my mechanic and I will be testing various components this week in attempt to troubleshoot.

At one point, my mechanic was wondering if the software was causing the issue(s), however I don't feel that is the case here. I mean, wouldn't the software have given me issues while running it on the K03 for 3 months or so prior to installing the K04? At one point I was considering the the software may have been written for larger injectors, but even on the K03 and 4BAR, no lean/rich fuel trim values per Vag-Com. Poor written program from Speedtuning? Could be I suppose since anything is possible, but again why wouldn't I have had any issues on the K03 setup if that was the case? Obviously since the K04 allows more boost that "could" be why things are more noticable with overboost, but you'd figure the same would've happened with the K03 since any turbo can "overboost." Oliver sounded 100% confident that the program was for stock injectors, and one reason being that he didn't have a larger injection program, as he'd have to "find one" is what he told me, but being that it would've been more money and the cost of injectors, larger MAF, etc...not worth the small gain from the standard K04 program on stock injectors IMO.

I'll be keeping people updated once we begin to eliminate possibilities as the week goes on.

 

Mbc's are cheap and easy to install, not sure why you are against it. But anyways it's your car do what you want, as far as the wastegate: it's possible it is stuck, my previously owned k03 had a crap wastegate but I knew it was bad as it would boost 20+ psi and let off extremely hard and violently. Try the hose between the compressor housing and the wastegate, that will tell you if you wastegate is stuck. Again, disconnect your battery. Your ecu has adapted to the k03's flow, it might not do much but it's s start and will let your ecu reset and learn again.

 

I'm not against it so much, however it shouldn't be "necessary." If it were, tuning companies would either require it, or at least "recommend" it. On a basic K04 application and tune, you shouldn't have to install a MBC, if so, there's an issue that's not being addressed directly IMO. With that said, I'd rather find the root problem. Make sense?

My ECU was already cleared of any codes (although the MAF is back because of the overboost), but I didn't think unplugging the battery was any different than Vag-Com use to clear everything? Either way, it's an easy thing to do so I'll give it a whorl.

Upon checking the N75 and Wastegate this week, if we cannot find and/or solve the issue, a MBC will be the route I go. Like I said above though, in having to use one "seems" like you're just beating around the bush if you will....that's my only gripe. In the long run, if the MBC prevents the overboost, heck then it's a no-brainer.

 

I am almost positive the issue if the wastegate, as I had a similar problem. But for a $50 mbc I would do it just to reduce the risk of blowing your $$$$ engine. Unplugging the battery will actually completely reset your ecu, clearing the codes doesn't. I don't think it will do much but like you said its easy enough to do that you should just go for it

 

I'll have my mechanic look at the wastegate seeing as he knows how to adjust if needed. On Audizine, there's a couple of guys who have had the same problem I'm having, and both have said adjusting the wastegate rod is easy. If my mechanic checks it out and it's still having issues, I'll definitely get the MBC. Thing is, I don't even know where to set the max boost on it, the tune GIAC has is the most similar I've seen for stock injectors and they said theirs runs on 20psi, but I guess I'll cross that bridge if needed.

The other thing that confuses me however is that you're now saying it's "for sure" the wastegate, although earlier in the thread you said the opposite. What's your reasoning out of curiosity?

 

Just got to thinking about it and realized if you are boosting that high there's more going on than just needing a mbc (which is easy to set btw). I replaced my k03 with a used one and it had a stuck wastegate, similar problems but it snapped forward violently when I let off (does yours do this). Are you sure you hooked up the n75 correctly? It would cause the same symptoms

 

The N75 wasn't touched during the K04 install, didn't need to be. The N75, DV, etc etc were all working proper one day before the K04 install to my knowledge, I'm assuming this because everything was running tip top. The more I think about everything going on, and what input people here and Audizine have given me, I'm with the "wastegate for sure" theory.

 

The n75 wasn't touched but the lines leading to it were. Looking from the passenger side (airbox side) the top line should go to the wastegate and the perpendicular side should be going the the compressor housing