Also check your intake piping. I had blown my hot-side pipe off the turbo and it was doing that. It could be any of the piping between the turbo and intake manifold that has come loose, or as someone experienced a few months ago, the flexible parts could have torn.

EDIT: oops, nevermind... apparently I missed that 2nd paragraph.

 

Your ecu was retarding timing for conditions preventing what your calibration would allow. Could be any combination of poor spark, additional load, higher IAT or reduced octane due to bad fuel or oil mist thru the PCV. I'd guess quality of fuel from the pump, try adding octane booster to see if it resolves it.

 

Mikesk-Gas is fine, same issue even after adding gas. Interesting to think its retarding the timing, but don't think it would cause a low boost condition?

 

it to the dealership to diagnois, and they said it was fine, measure peak boost at ~34psi so doesn't seem to be leaking.

Excuse me? That should be a big red flag for trusting your dealership right there. Do you have a massive built motor? Stock is what, 15psi normal, 22psi on overboost? I run peak of 28psi, with the average being 24-26psi to redline, and that’s heavily tuned with water/meth.

 

Well that's definitely interesting. The dealership experience was less than confidence inspiring, to say the least.

From their notes "turbo boost pressure desired highest was 34.9psi and actual was 36.16 psi. Turbocharger is actually working better than the computer is commanding".

I'm still learning about this car and wish I knew what psi was normal for a stock car. I sure would of made a bigger deal out of it than I already did!

So my question is now, is it physically possible for the stock turbo to reach ~35 psi? Is the dealership just full of it?
Or is something else hindering the performance where the ecu is asking for that much boost to compensate to hit the power target?

Thanks

 

Actually, thinking about it now, I bet their measurement is absolute pressure and not gauge pressure. Subtract 14.7 psi from their measurements and things look more in line.

 

If the boost control solenoid is not operating then the boost will likely be restricted to spring pressure which is about 12psi which would make the car seem slow

It’s mounted on side of the engine (timing chain end), remove it and test it. Put a current across the solenoid and you should hear it operating and should be able to blow air through when powered up and opened

 

2017 with ~25k miles and I was getting on the freeway when it felt like the engine power was cutting in and out. ALmost like boost was fluttering (best way I can describe it). Got out of the throttle and it smoothed out, but immediatly got a CEL. Car was driving fine, so babied it the short drive home. Checked the CEL and it showed P0299 for low boost condition.

Cleared the CEL and went for a drive to see if it would come back. Couldnt recreate the event or the CEL, but the car is noticably slower to respond, seems like it takes much longer to build boost and power. Took it to the dealership to diagnois, and they said it was fine, measure peak boost at ~34psi so doesn't seem to be leaking.

Only had the car for about 8 months so still learning the mechanics, but from what I've learned is that boost/wastegate solenoid (seems like the same part goes by different names?) could be to blame.

Would it be possible that instead of the solenoid not allowing full boost, could it be reacting slowly? So it still allows full boost, as the dealership measured, but just taking twice as long? Also, any tips on how to replace it would be appreciated as well! Thanks!

Theres no way boost should be 34. Max is near 24 on these engines. Possibly a clerical error but that makes me doubt the diagnosis. I would have the intake smoked before I put a bypass valve in it.

 

psia, subtract 14.7?

Beside that the low boost error comes after a long time (several seconds) being well below expectations for the given throttle demand. The CEL came for a reason.

Check the electrical connection to the wastegate solenoid. If you pull up the coolant expansion tank and move it out of the way you’ll see everything clearly: it’s on the front-left of the engine below the exhaust camshaft sprocket (the engine front being where the timing chain cover is, looking transversally.)

 

Hence why I advised op to pull the solenoid and test it

 

Hello, does anyone know a p/n for the correct bcs? very hard to find

 

 

Ok I appreciate it @axelr Ordered from Amazon most of the numbers seem to line up except for couple at the end. Hopefully it works.

 

Ok I appreciate it @axelr Ordered from Amazon most of the numbers seem to line up except for couple at the end. Hopefully it works. Amazon.com: Pressure Control Valve Sensor OEM 31219138 70222100 For V-olvo S60 S80 V60 V70 XC60 XC70 : Automotive

You are welcome. The OE ones in our cars are made by Pierburg in Germany:

Note the tiny barbs on the input (the side with the metallic pipe) that comes from the compressor.

On the RS they used a bit of thermo-retractable sleeve to secure that connection. When you undo it it’s a bit destructive and it won’t hook well to the next valve. You have to pay great attention to that connection and make sure it’s secure and air-tight at 2+ bar.

The second important one is the beige perpendicular output that goes to the capsule. If either fails or leaks the turbo will overboost.

 

2017 with ~25k miles and I was getting on the freeway when it felt like the engine power was cutting in and out. ALmost like boost was fluttering (best way I can describe it). Got out of the throttle and it smoothed out, but immediatly got a CEL. Car was driving fine, so babied it the short drive home. Checked the CEL and it showed P0299 for low boost condition.

Cleared the CEL and went for a drive to see if it would come back. Couldnt recreate the event or the CEL, but the car is noticably slower to respond, seems like it takes much longer to build boost and power. Took it to the dealership to diagnois, and they said it was fine, measure peak boost at ~34psi so doesn't seem to be leaking.

Only had the car for about 8 months so still learning the mechanics, but from what I've learned is that boost/wastegate solenoid (seems like the same part goes by different names?) could be to blame.

Would it be possible that instead of the solenoid not allowing full boost, could it be reacting slowly? So it still allows full boost, as the dealership measured, but just taking twice as long? Also, any tips on how to replace it would be appreciated as well! Thanks!

How did you fix your problem?

 

I just replaced that Solenoid with a generic one from amazon that looks the same and said it was for RS and a couple other cars. Was a real pain to change. Boost is more consistent now but still not getting above midway on the gauge, not full power. Cleared the P0299 code to see if it's in some limp mode. Testing in progress.

 

Solenoid didn't help mine at all either. I changed it in like 25 minutes the 2nd time. The first time sucked until I figured out how to do it. I'm getting like 24psi and its cutting to like 14 and then climbing again. Over and over. It just won't hold boost above 20psi. I just got a p2195 code the other day too. I'm so tired of this car.

 

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?

 

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.

 

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.

 

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.

 

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.

 

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?

 

Take the BCS off and test it to be sure

 

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.

 

Good find

 

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.

 

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.