# Need help with 16683 - Boost Pressure Regulation



## fabric8 (Jul 4, 2000)

I need help figuring out what to do to troubleshoot this code:

1 Fault Found:

16683 - Boost Pressure Regulation 
P0299 - 35-00 - Control Range Not Reached

Readiness: 0000 1101

The car is an 05 TT225Q BAM engine code. The engine is all stock except for an APR stg1 tune and Hyperbooost DV - both installed around 10k miles ago. The car has 80k miles. About a week ago, I replaced a leaking t-stat housing along with a new t-stat. I *think* that's around the time I noticed the car not making any power. There's never been a CEL, but the above code is logged immediately after any run. Boost doesn't come on until about 4000+ RPM and only peaks to about 11 (instead of the ~19-21 psi) it used to make.

I've done several boost leak tests and can't hear any leaks. I'm at 19 inHg on idle and 21inHg under decel. I ran VCDS tests for my N75 and N249 and can hear both clicking on/off. I took apart my DV and cleaned it (although it was pretty clean). I also used my air compressor to blow air into the line to the wastegate actuator and can hear it click back and forth. I also disconnected the line from the DV to the turbo wastegate actuator and drove (carefully), but there's no difference in making boost. I also cleaned my MAF. I also installed a new air filter.

I'm really stumped and can't figure out why I can't make much boost. I get the same behavior when I switch to stock mode on the APR tune. Hardly any boost, and lower peak at redline then when in chipped mode.

I double checked all the vacuum hoses under the intake manifold close to where the t-stat housing is, and they're all good. I really don't know where to go from here.


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## Boulderhead (Oct 21, 2012)

What does your long term fuel trim look like (block 32)?


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## lite1979 (Sep 9, 2005)

Do you have any shaft play in the turbo?


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## fabric8 (Jul 4, 2000)

I was able to get the TIP off today and felt for shaft play. It's very, very minimal - about 1mm total side to side - if that. And the impeller vanes look perfect. No wear nor wear on the inlet.

Here are my 032 readings:
Group C:	'032 
Group C:	'032 
RPM Lambda	Lambda
TIME 
/min	STAMP % %
1560	0.58 0.4	-0.8
1760	1.48 0.4	-0.8
1960	2.39 0.4	-0.8
2200	3.29 0.4	-0.8
2480	4.2 0.4	-0.8
2720	5.1 0.4	-0.8
3000	6.01 0.4	-0.8
3240	6.91 0.4	-0.8
3520	7.82 0.4	-0.8
3800	8.72 0.4	-0.8
4080	9.65 0.4	-0.8
4360	10.54	0.4	-0.8
4720	11.44	0.4	-0.8
5040	12.36	0.4	-0.8
5400	13.25	0.4	-0.8
5760	14.17	0.4	-0.8
6040	15.07	0.4	-0.8


I tried to pull the actuator rod away from the actuator to operate the wastegate, and I can only get it to move about 1-2mm. And I can't push it toward the actuator. Is that normal? Could my wastegate be stuck open?


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## Marcus_Aurelius (Mar 1, 2012)

Yes, it's likely that your actuator is stuck open after what you've described.


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## fabric8 (Jul 4, 2000)

Does it sound like the actuator is stuck or the wastegate flap is stuck? I read on some other thread that it's quite difficult to try and move the actuator rod by hand. I'll try applying 8-10 psi to it today to see if it moves.


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## fabric8 (Jul 4, 2000)

Ok so here's an update. I applied 10psi to the actuator line and could see it only move about 2mm. I increased to 15psi, same result. I then removed the outer nut holding the actuator rod to the wastegate lever, which relieved pre-load on the actuator and with 10psi, the actuator moved perfectly.

I then played with the wastegate lever after disconnecting it from the actuator rod, and it does move freely, but at the closed position, the lever is about 1/4" away from the flange and is angled back - toward the flange. In almost every pic I see of K03's and K04's, the wastegate lever is either parallel with the flange or angled toward the actuator.

I suspect that something is preventing my wastegate flapper from fully closing. That's probably why my actuator isn't moving much, because at the position the wastegate flap is in, it's probably almost fully open, and the actuator doesn't have much more travel.

So, if my wastegate is not fully closing, I guess the best way to confirm is to remove the DP. I can easily feel 2 bolts, but the 3rd is tough. Can this be done from the topside? What do I need to do to get the DP off so I can inspect the wastegate flap?


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## fabric8 (Jul 4, 2000)

Before I pull out the DP to check the wastegate flapper, can anyone tell me if a pressure test would indicate the flapper is stuck open or missing? Will air pass through the turbo inlet and leak through the wastegate in a pressure test?

Because when I pressurize the system, air pressure holds (it decreases slightly over time from the oil gurgling which I hear is normal).

I'm wondering if my CAT my be bad, because today I happened to check for readiness, and everything passes except the catalyst. I'm hoping it failed and is blocking flow causing my turbo not to be able to spool. I'm hoping to pull the cat off tomorrow to inspect it.

Any other ideas fellas?


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## lite1979 (Sep 9, 2005)

Regarding the actuator, a little PB blaster and small pair of vice grips should get it moving like normal after some effort. You can usually wrestle the downpipe off after you get the three 17mm nuts off. The hardest one to get to can be reached with an extension from the passenger's side wheel well. Since the 225 came with two catalytic converters in parallel, it's not likely they're clogged. If you give us an exhaustive list if your DTCs, we can figure out what is causing the cat code. It's most likely related to your turbo not making the requested boost, though, which is probably related to your waste gate problem.

I just went through this last year with a k03 on a 02 Jetta that sat for a while.


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## fabric8 (Jul 4, 2000)

*I think I got to the bottom of it!!!*

OK guys, I was able to pull off my CAT today and sure enough, it looked perfect. I then worked on removing the DP from the turbo. That last bolt was really a pain to remove. Thanks to lite1979 for suggesting accessing it from the passenger side wheel well.

Once off, I could feel my wastegate flapper could not close all the way. It was as if it was misaligned. I decided to mess with it and was able to push it back to where it now closes all the way. It turns out the bushing for the wastegate flapper arm is loose allowing the flapper to become misaligned.

Here's a video I took of what I'm talking about:

https://youtu.be/GUujAqDkiRg


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## fabric8 (Jul 4, 2000)

As much as I would have wanted to have the bushing tac-welded, my neighbor didn't have one. So I went down my local non-chain carparts store where the guys behind the counter are old gear heads with yrs of experience. They recommended *Permatex Bearing Mount* to keep the bushing in place.

So I pulled the bushing as far out as it could go, cleaned it with a wire brush and brakekleen, then applied the Permatex Bearing Mount around the bushing and pushed it back in with a twisting motion setting it into position. I was skeptical that it would hold, but after 2 hours (full cure time), it felt really solid.

I decided to go further, so I took a 1/2" copper tube, cut it 6mm wide (the width of the exposed bushing), then cut it in half and glued both halves to the bushing with JB Weld. I'll give it the full 24hours before I try the car again and will start bolting everything back together tonight. Hopefully this takes care of it.


















Pic of bushing showing copper tube halves glued to bushing with JB Weld.


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## lite1979 (Sep 9, 2005)

I have a good feeling you're going to make a big mess with what you did there. The turbo gets ridiculously hot, and the only thing that can withstand those temperatures is metal or ceramic.


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## fabric8 (Jul 4, 2000)

The permatex stuff if rated to 300º F, while the JB weld is rated at 500º F. If they should both fail, worst case scenario is I'm back to square one and will try to get someone to tac-weld it in place like [email protected] suggested. Or clamp it.

Any other ideas?


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## Marcus_Aurelius (Mar 1, 2012)

Jb weld anything on a hotside of a turbo is a "get-me-home" repair at best. Have the thing welded man, the Jb weld is rated at a 1/4 of the temperature reached by these small frame turbo on a constant basis. :what:


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## Marcus_Aurelius (Mar 1, 2012)

fabric8 said:


> So it's been 3 days and 80+ miles since I "fixed" the loose bushing that was causing my wastegate flapper not to fully close, and the car is running perfect.
> 
> One member warned me that the JB Weld would not hold up to the heat. JB Weld is rated at 550ºF, while the Permatex Bearing Mount is rated at 300ºF. Apparently, these turbo's operate anywhere from 1300ºF-1600ºF. I checked the bushing this morning and sure enough, the JB Weld I used to glue the 2 copper tube halves to the bushing has turned into a hard white powdery substance. While it's still holding, if I mess with it, it breaks down easily.
> 
> ...


GL, welding like I mentioned is the proper fix (the JB weld will completely disintegrate in the near future). It might be hard to get good beads on without removing lots of things that are in the way. So, it could turn into more than a 12 pack project.


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## lite1979 (Sep 9, 2005)

I wish you were near me in Buffalo, NY. The guys who welded my shift stalk after it broke are excellent, and only charged me $30. I'd look for a similar business that can maybe come to you.


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## Ric_ross (Mar 3, 2011)

*code 16683 and 16804 help.?? caused by removal of CAT??*

just put DP in and everything was ok . i took on a trip after about 35-40 mile CEL came on and this boost pressure reg control is really pissing me off . i dont know it caused i removed my CAT. but at first no lights came on after the CAT removal. could have it just went through the cycle and just pick it up. car is stage 3 apr programmed . but also not sure if it holding the program, but that a different story. but was wondering if there is not CAT would it throw off the boost pressure reg ? please help. just got this car . and did the timing water pump and stat. pretty penny.. always a love hate relationship but i hate my dash looking like a christmas tree. even if anyone local to meet up I'm in NYC. PLEASE PLEASE help...


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## fabric8 (Jul 4, 2000)

Is your wastegate bushing loose like in my vid? Maybe your wastegate isnt closing all the way like mine was causing that code

Heres how i fixed mine when the JB Weld stopped working:


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## Marcus_Aurelius (Mar 1, 2012)

Ric_ross said:


> just put DP in and everything was ok . i took on a trip after about 35-40 mile CEL came on and this boost pressure reg control is really pissing me off . i dont know it caused i removed my CAT. but at first no lights came on after the CAT removal. could have it just went through the cycle and just pick it up. car is stage 3 apr programmed . but also not sure if it holding the program, but that a different story. but was wondering if there is not CAT would it throw off the boost pressure reg ? please help. just got this car . and did the timing water pump and stat. pretty penny.. always a love hate relationship but i hate my dash looking like a christmas tree. even if anyone local to meet up I'm in NYC. PLEASE PLEASE help...


The two codes are not related. 

One code is caused by the cat delete. You can look into the 02 spacers, electronic 02 simulator fix, or have the rear 02 written off on a tune. There is no way around this one (except for the fix mentioned) if you run without a cat. 

The boost pressure regulation code is caused by discrepencies in your boost pressure (boost actual vs boost request). If the deviation is too large for some reason, the ECU will throw this code. There are many possible causes, so it's on you to diagnose and fix it. Large boost leak, failed DV, failed N75, holes through (or disconnected) N75 lines (especially the one going from N75 to the wastegate actuator), N249 going crazy as usual etc. are all common possible causes. 

The first thing I'd suggest is a pressure


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