Tune with inlet pipe replacment?

[ants87ss]

I have a '08 MS3 I just replaced the head gasket on. Stock inlet pipe broke so I replaced with JBR pipe and intake hose, but kept stock airbox. The car breaks up on light throttle at low rpms. I have checked for vaccuum and boost leaks and found none. I have no codes. Would I require a tune even though I kept stock airbox? I am using the free version of VT to log and get data to try and diagnose the issue. I notice that my STFT gets in the 20s while driving, which would indicate a vacuum leak, but as I said I have checked everything. Thanks in advance

[mituc]

Nope, no tune changes required for what you did on the car to fix it.
If the STFTs get to 20 then most likely you have a vacuum leak as you suspect.
Please download this dashboard preset and take a log with the car breaking up, post the log here and let's look:
https://www.dropbox.com/scl/fi/55qyxbqs ... khuf9&dl=0

[ants87ss]

Here's a log from a third gear roll on

[mituc]

You need to service/replace your HPFP (or the internals). ASAP, because they are damaged or the pump is clogged.
Also, the boost control system is not working on your car, one of the lines going from the turbo compressor housing to the wastegate actuator or from the wastegate actuator to the EBCS (or both) is disconnected or cracked (or chocked if it's the one from the compressor housing to the wastegate actuator).

Also your engine coolant temps readings are very weird, the temps is raising very fast, probably because the engine is now a flame thrower with this fueling issue going on, or maybe you have a stuck semi-closed thermostat (or was replaced with an incorrect unit).

And by the looks of it your car may also require servicing of the timing parts.

So yeah, it doesn't look good at all...

[ants87ss]

Thanks Mituc. Yes, I noticed the engine temp rising quickly as well. I replaced all timing components when I replaced the head gasket except the variable timing actuator on the intake cam. I will service the hpfp and take a look at the hoses going to the wastegate and solenoid as well, and report back. Thanks a ton and I appreciate your feedback

[ants87ss]

So I rebuilt the hpfp with all new components. Runs a slight bit better, but not great. I checked all vacuum lines from the turbo to and from the actuator and solenoid, and all seemed good. Here is another log from after rebuilding the pump. I noticed the ecu is commanding 100% ebcs duty cycle as soon as the throttle is pressed. Is this normal? As i watch data, the car runs like garbage until the ecu starts pulling back duty cycle. Any and all help would be appreciated. Im at witts end with this thing

[mituc]

In this log you revved the car stationary... it's really hard to figure out anything from such a log with 500+ rpm increase per log line.
And yes it is normal for the ECU to command 100% ebcs duty when you press the acceleration hard until the desired targets are reached.
If the car driver and reacts worse than before you replaced the pump internals then go back and see if you left anything disconnected: wires, pipes/hoses and small lines on top of the intake manifold or to/from the EBCS.

[ants87ss]

In this log you revved the car stationary... it's really hard to figure out anything from such a log with 500+ rpm increase per log line.
And yes it is normal for the ECU to command 100% ebcs duty when you press the acceleration hard until the desired targets are reached.
If the car driver and reacts worse than before you replaced the pump internals then go back and see if you left anything disconnected: wires, pipes/hoses and small lines on top of the intake manifold or to/from the EBCS.

Sorry Mituc, I uploaded the wrong log. Here's a better one

[mituc]

I really do not see any abnormal behavior in this log, but I agree that from inside the car things may feel totally differently.
There are two things that caught my eye though:
1. the intake manifold is incredibly hot. the coolant temp is in the low 100C and the intake manifold air temp is in the high 70/mid - 80C, and even reached 92C/197F when accelerating a bit more spiritedly in 2nd and continuing with 3rd gear to 4000-ish rpm. Was the car idled a long time before you took that log?
2. fuel trims are sometimes all over the place especially when you push the acceleration a bit firmer. Seeing by example -12 LTFT and +12STFT makes me think you have both boost and vacuum leaks. Are all your EBCS lines properly connected? Did you check your car for intake and exhaust leaks? Do you hear any weird sound when you push the acceleration?

[ants87ss]

No abnormal noises really. I get some pops from the exhaust on decel at times. Under boost I can hear the turbo. When leaving a stop, if I attempt to leave like normal the car almost bogs down. I have to feather the throttle to get the revs up and then continue on. I will double check both vacuum and exhaust for leaks. Thanks Mituc. Appreciate your insight and I will update with what I find