[gr8whte]

Hey guys,
Just a little background. I've been running Lenny's tune with Bohl's DP for about two years now. Car's been running great without any issues since the carbon cleaning, which happened right at the end of my warranty before I modded the car.
Now the car is at 73K, 2011. Last summer I've replaced all the accessible vacuum lines, pressure controllers, and the red boost pipe. As part of maintenance.
I live in South Florida and don't have a garage, so I try to do stuff in a bulk at a DIY Garage down in Miami, about an hour drive.
Everytime I pray I won't fuck it up and end up getting stuck there, as I haven't lived here that long and don't really have any friends who could lend me a hand, so every time I go to work on my car it has to be drive-able for me to make it home. Otherwise I'd be stuck in not the nice part of Miami, 60 miles from home and running a tab for the DIY garage.

Now,
recently I started having an issue with my car. Was running some errands with the wife on a weekend, a few weeks back, cruising in traffic at about 1200 rpm.
Traffic picks up, so naturally I give it some diesel, and was like WTF, we're not really accelerating, RPM climbing pretty slowly.
Look in the mirror and there's a huge cloud of black smoke behind me.

Since then I've been trying to figure it out and kinda pinpoint the conditions under which the car behaved in such a way.

in the meantime I've replaced a Sensor on the Intake # 13627792260, as I've read some people were having issues with it, a low cost item and took like 5 minutes to do. No improvement.
Had a spare EGR valve laying around, that I haven't replaced yet. So I did that real quick. Same thing. 11747810831
EGR is blocked off BTW.

So I finally took it to the dealer and came out with nothing.
Short conversation with the rep basically adds up to the tune keeps erasing the codes off the top, so they couldn't diagnose shit.

I have some maintenance overdue, such as the fuel filter, oil change, so I'm planning on running down to the garage in Miami, at $25/hr it's a good deal, cause you have a lift and some basic tools, but it's not a place you'd want to hang out at and fiddle around with stuff, there's no A/C and with the summer heat you just want to get shit down and grab a cold one.

Sorry for the long post and the rants. My next option would be finding a decent Indy Garage that would take the time to figure it out. But I know there are quite a few brilliant D owners out there, so any insight is welcomed and hopefully my experience can help someone out down the road.

Here are the symptoms:

Now, before you'll call for a boost leak, these symptoms are intermittent.
Meaning the car will run fine one minute and then it'll act up.

Another thing is when it doesn't run "right" the engine is more audible, I can tell by the sound of the engine whether it's acting up or not.

From a stop it starts fine. But becomes louder approaching 3K RPM, I usually let go at that point cause I can tell it ain't right, and I can see serious black smoke.

Cruising at about 1500 RPM and giving it slight diesel results in slow climbing RPMs and a lot of black smoke, not really accelerating.

I can "push" through and it'll pick up the power but the engine will still be louder than normal.

Now, 1500-3000 RPM, if I understand correctly is when both turbos work inline. I'm thinking of replacing the Pressure Converters once again, as maybe I had gotten some cheap-prone-to-failure ones. And it really wasn't that big of a job. I think it took me just an hour to replace all the common vacuum line and pressure converters the first time.

What do you guys think?
Thanks in advance and sorry for the long post.

[robnitro]

If you have torque and a bt obd plug, you should watch parameters such as boost pressure, mass airflow egr (if it's asking for it but deleted, the throttle next to the egr valve can close to try to increase egr.... on some past tunes i read this can be an issue.)

You could also have an intermittent boost leak, when that happens your boost will show low but the mass air flow will go up quickly.

Here are my torque custom pids if you want to see the ratio of boost vs airflow, use the maf customs i made, one is by rpm, and the other is a step further using boost to find flow per bar of pressure, both of which have been useful when i had a TDI and still apply here.

Air mass r is maf g/r like the vagcom tdi would show. Air per revolution/stroke.

Air per bar is the one that will help diagnose a leak or airflow clog issue.
Normally without egr it should be around 500 mg/r/bar. If it's way higher: boost leak.
If it's way lower: egr in use, or bad maf, or intake restriction (or in our cars the throttle is closing)

[135i_vs_]

Hard to tell without codes, but symptoms point to the MAF sensor...

[robnitro]

Try to log it or watch it while it's happening.

I don't know how it could be the maf, if you are smoking... Usually mafs fail by reading low and fueling decreases giving low power, and no smoke.

My feeling it has to do with that throttle by the egr, which has been an issue on some tunes

[digitaldav]

Bump..
Because Im curious on diagnosis..

[gr8whte]

I took a half blind shot at it, ordered a new MAF sensor from Amazon. It was fairly cheap, so I figured why not try it, since the car's been running like shit with the symptoms described above.
And that was that. It was a bad MAF that caused all that havoc.