Hey guys! I've been struggling with my N14 engine for a while now.

The car has this problem, when I take off from a stop, it feels like sometimes there is no boost in 1st and 2nd (but I can hear the BOV) From 3rd gear I can feel the "torque" from down low.
The main issue is that I can't give the car full throttle because it starts backfiring through the intake I guess (loud puffing from the engine bay). I've been using the car on quarter throttle for a while now,
but I can feel jerking, but just one when it builds up boost.
Also when the car is idling, sometimes you can hear, and feel that 1 cylinder just "thinks" for a second, some sort of misfire?

To eliminate some guessing, I write down what I have changed on the car:
- Timing chain, tensioner
- Oil pump chain + sprocket
- VANOS wheel and solenoid
- Turbo renewed at 90k km (now has 120)
- New Bosch injectors
- Rebuilt head, valve seals and all cleaned up.
- Catless downpipe, midpipe delete.
- PCV deleted.
- Airbox drilled out, and brand new air filter.

As for live data:

- HPFP reads 48-50 bars at idle, 70-100-120 on load.
- The upper MAP sensor i couldn't figure out a number, but the intake MAP sensor had 1.5 bars one time which I think is too much.
- Also I have an option in Carly OBD that I can see the ignition advance that was taken away because of knock. It had that before replacing the injectors, now I don't know if it does that.

My question is, should I go buy map sensors and try that?
I linked the videos what it does on half throttle.
https://youtube.com/shorts/2TUTWDubdkw?feature=share
https://youtube.com/shorts/ei-csTzvoj4?feature=share

 

Did the problem start after the timing chain replacement? Any engine-related codes stored in the ECM?

https://www.northamericanmotoring.co...ml#post4649785

 

No it was already a problem before. I just went on a little drive to log some data. Here are the results. HPFP numbers aren't looking so great. Also the LTFT is solid at 20%. At idle you can hear some puffing sound here and there, like a misfire. https://youtube.com/shorts/x0JErn2_HIo?feature=share

 

Why did you delete the PCV? A properly functioning PCV is important to a smooth running engine
When was this performed? What was your motivation for delete?

 

I did it to prevent the engine from getting dirty. Plus the PCV membrane was ripped so it had an intake leak

 

LTFT should be near zero in a properly running engine; general limits for LTFT is +10 to -10; when you see numbers higher than 10 (positive or negative), you need to take action to isolate the cause. What is the STFT?

I recommend a cylinder leak-down test.

 

I can't really trust these Bluetooth OBD scanners, I am going to take it to my friend to look at it with a Diagbox.

Also today the car developed a new habit. When I am cruising on any speed, barely touching the throttle, I can feel that the boost just goes away, and not coming back. I tried restarting it, nothing changed. Then after a few blocks, in 4th gear it started pulling like hell. I was like what, it never was this powerful.
Then about 20 miles later there was no boost again, couldn't really get it into 4th because of traffic, so I started doing little pulls in 2nd.
The thing I noticed to fix it was I gave it gas to around 2k, letting off (BOV barely doing the shh sound), then pulling again (somewhat bigger BOV sound), and pulling again, and then it was fixed.

Very strange engine, all I can say. I think it could be a bad turbo, or a wastegate solenoid. I already noticed that there is some play in the wastegate housing, but idk.