[JamoRS]

Update: Still bad.
If I clear the P0299(low boost) using Accessport then take it for a drive every thing is all good being light on the throttle. Then when I punch it boost goes part way up and "Service Engine" fault light appears on dash and P0299 is back. So the code is correct. Haven't found any cracks or loose hoses yet. Now what?

Another thing I noticed is with the ignition switch in ACC mode, engine off, the replaced wastegate solenoid is buzzing(cycling) at >60Hz. Is that normal? I guess this helps me prove the wiring harness to the solenoid is good.

What about the AIT sensor?

 

[axelr]

Tuned or not?

Another thing I noticed is with the ignition switch in ACC mode, engine off, the replaced wastegate solenoid is buzzing(cycling) at >60Hz. Is that normal? I guess this helps me prove the wiring harness to the solenoid is good.

It’s 31.25Hz and 10% duty cycle. Normal.

I forgot if the car was tuned or not?

 

[kampto]

I recently cleaned the AIT (near air cleaner) and MAP (intake manifold) sensors, no improvement. I suspect if one of those was dead I would have additional codes come up. Anyway to bench test these sensors?
I have a COBB stage1 OTS tune, last time i removed it no change but I can try again.

 

[axelr]

I recently cleaned the AIT (near air cleaner) and MAP (intake manifold) sensors, no improvement. I suspect if one of those was dead I would have additional codes come up. Anyway to bench test these sensors?
I have a COBB stage1 OTS tune, last time i removed it no change but I can try again.

Remove as in uninstall the AP, right? This restores the OE calibration that was present when the AP was first installed. I would try that just to rule out one big variable.

The sensors are probably fine, save for one possible issue: the MAP sensor may be soaked in oil and its pressure pickup clogged. You can spray it with brake cleaner a couple of times and let it dry overnight nose down.

 

[maxmike181]

If you do go cleaning the MAF or MAP, I recommend SensorKleen over brake cleaner. It's basically the same stuff but SensorKleen is under a lot lower pressure which lowers your risk of dmaging the thin wire filaments.

 

[jettic]

Consider the BPV if yours is the stock OEM part: Stock BPV Fail

I'm not sure if the ST and RS share the same part, but they look similar enough based on google images

If the stock diaphram ruptured, some of the sypmtoms experienced on this thread and the one linked seem like reasonable outcomes.

 

[kampto]

Consider the BPV if yours is the stock OEM part: Stock BPV Fail

I'm not sure if the ST and RS share the same part, but they look similar enough based on google images

If the stock diaphram ruptured, some of the sypmtoms experienced on this thread and the one linked seem like reasonable outcomes.

I put vacuum hand pump on these places and it held vacuum. So that BPV(TRV) valve is not ruptured. Too bad, would have been an easy fix.

 

[Focused]

BUMPing as my car just started experiencing this—low boost (max 13.xx psi) on WOT runs, but the kicker is: no codes thrown. My tuner is led to believe it’s the BCS since my WGDC is virtually 0 on my WOT logs.

Add’l info: I did 2 back to back pulls within a min, whereas the first pull was normal, and then the low boost condition occurred in the 2nd pull immediately after. No weird sounds or drivability noted then or afterward, other than the breathtakingly slow acceleration. Also, switched to a previous tune file just to make sure it wasn’t the tune, and same low boost condition occurred (again, no codes).

I’ve done a quick charge pipe inspection, nothing looking out of whack. I’d think a 10+ psi leak would be a fairly obvious leak.

1) any thoughts? Do BCSolenoids just randomly check out like this? Is it possible for it to go without throwing a code?

2) did anyone else’s previous situations in this thread ever get resolved?

 

[Pezzar]

Take the BCS off and test it to be sure

 

[Focused]

Update for my situation: boost leak, rather large tear in Mountune silicone hot pipe (second occurrence smh).

Will work on replacing IC pipe in order to fully rule out BCS 100% but rn this looks like it. Testing BCS is still an option but time to work on car is limited atm so this is a welcomed find.

 

[Pezzar]

Good find

 

[ATXFocusRS]

I recently cleaned the AIT (near air cleaner) and MAP (intake manifold) sensors, no improvement. I suspect if one of those was dead I would have additional codes come up. Anyway to bench test these sensors?
I have a COBB stage1 OTS tune, last time i removed it no change but I can try again.

So I'm curious here. This is basically my issue. We had over boost code p0234 I think. We swapped..
New battery (reset BMS)
New Solenoids, top of cave cover and timing chain side (lines are correct)
New MAPT and MAP sensor
Cleaned the cold air intake one
Swapped the WGA with newer OEM.
Changed the solenoid oil filter

Not tuned never has been, no aftermarket stuff.

Turns out, we swapped the PCM relay with blower motor one. Never got the code back. So I believe that was the issue.

NOW we have this doggy boost issue. Car makes some, more than just the spring. But still not pushing like it was. I know what it's like with just the spring since I had plenty of ruined autocross runs because of it. This is more like 3/4 boost. I have a feeling I'll be testing all the vacuum lines...

Always open to honest good advice.

 

[NISMO_IX]

I'm just catching up on this thread.

Sorry @ATXFocusRS I don't have any help for you.

But I am getting an occasional "under boost condition" as well. So this thread has me wanting to check a few things now.

 

[Pezzar]

If you’ve replaced just about every possible part then check the vacuum lines for sure, what obd codes do you have stored

 

[ATXFocusRS]

If you’ve replaced just about every possible part then check the vacuum lines for sure, what obd codes do you have stored

Nothing for under boost. The old code was the over boost p0234 I think. But we believe it was the PCM relay. We swapped it with the blower motor relay till the new one arrives. Been a few events now and no codes.

Here is what I found that I believe is the issue with this 3/4 boost issue.
I'm a fool, I didn't have the WGA nuts on the backside of it. So it wasn't able to close the gate 100%! So as silly as that is I'm happy to found that "should be" the issue.

Moral of the story here when chasing turbo ghosts... Check the PCM relay 1st! Easy swap and you will know! Then probably the WGA or TRV.