Possible boost issue - Alfa Romeo Turbo

Hi there.

Firstly I appologize if I write something wrong as I am from Slovenia and am not a professional mechanic.

I have an 2013 Alfa Romeo Giulietta 1.4 16v Multiair Turbo with 170 HP (gasoline/petrol - NOT diesel). I'm the second owner for the past 5 years and I service the car within the service intervals with OEM parts. Currently it has 126.000 km. Never had any problems apart from this explained down.

1) In the past year I had some issues with the car. I can hear the turbo switching ON/OFF when 100% throttle (in 3rd gear most noticable), but not feeling the difference on how the car pulls (maybe there is a 5% difference higher in the rev range, OR maybe I make my self feel the difference since I can hear the turbo switching on/off and believe that there is something wrong). This ON/OFF happens within half of a second or maybe less, the car does not bog down and loose power at any point. There was never any error codes on the dash or when we scanned the computer. The spark plugs were changed (NGK) in November 2023 thinking they were bad - nothing changed. In the 2024 I used the engine flush from Liquimolly and also injector cleaner from the same brand - nothing changed. In the attachment you can see the picture of the scanned turbo boost from a few weeks back. I hope you can read somethin from it. It looks like its not holding constant boost or perhaps it is supposed to be like this.

2) Once a month the car spits white smoke out of the exhaust for 1 second. I cannot simulate this problem when I am stationary at home. Happens when driving for say half an hour and then stationary at a red light and then coasting in gear down a steep slope at 50 km/h at revs 3000 - the I stop at the stop sign and immediately when i start moving I can see a white cloud behind me until I put much more gas (average time of smoke is 1 second, but there is allot of smoke). On the same route it happened twice in the past 6 months thats why I wrote the full journey. The oil separator (pcv valve or how is it called) is 1,5 years old. last week I opened it and it was full of oil which I sucked out. Yesterday another white smoke. Car burns oil 1,2L/10.000 KM. I drive the car every day and I am not easy on the gas pedal.

Can you please help me with those two problems? Are they related or are they each of its own problem? No Alfa shop in Slovenia knows what this problem is. They say drive it till something really breaks or the computer shows error code.

If you need more information please ask. This buggs me for the past year.

THANK YOU FOR ALL YOUR REPLIES!

Wish you all the best,

Luka

I'm totally unfamiliar with the vehicle, and not sure what you mean about the turbo' switching on/off but not feeling any difference? Do you hear the waste gate opening, which might be due to slight boost level limiting, I had thought of a possible over-boost setting being part of the problem, but would expect that to be quite noticeable, and only apply after some seconds?

The "white" smoke may be just the high cylinder vacuum under the over-run drawing some oil past the rings and/or valve stems, and then being burned off - it's a perfectly common event. As you're oil consumption is still very low, I wouldn't worry about it.

Given the mileage and age, I expect the turbo to be due for replacement, but there may be something else going on.

The boost control may be gummed up and need replaced. Sometimes spraying it out helps briefly, but they often need replaced by that age.

Keeping the PCV system clean and working is always important, so good job checking that out.

And before replacing anything, I'd check for any intake or exhaust leaks.

Hi.

Firstly thanks alot for replys.

I forgot to write that the engine is stock apart from BMC integrated air filter and a larger front mount intercooler.

Turbo switching ON/OFF is not actualy what I meant yes, I wrote it incorrectly. What I ment was that I can hear the turbo whistle on full gas, then one second you cannot hear it - and than again hear it and than not hear it whistle - keep in mind that I do not release the gas pedal.

About the high cylinder vacuum: Would this occour only once a month? I drive the car every day the same.

Boost controler is the little square thing that diverts vacuum hoses to the compressor housing and the wastegate actuator? Or is that the boost solenoid? Could this be the problem?

Could a leaking intercooler cause this kind of issues? Its not even 1 years old.

Thanks,

Luka

Yes the boost controller, boost solenoid, wastegate solenoid are terms often interchanged. that is the part I'm referring to.

Based on the image you provided, that looks like the boost oscillation I've seen many time from an old boost control solenoid. That doesn't guarantee it's the cause, but it's something I'd investigate. They often get gummed and no longer actuate as well as they used to. This can results in the ECU control system detecting boost off target and causing an over reaction which results in the on/off feeling you get.

The oil puff may be occurring when the air oil separator fills to a level where it no longer keeps oil out of the intake tract. The root cause may be a dying turbo, hopefully not excessive crankcase pressure from a worn engine. Avoiding the air oil separator from filling by more frequent draining is a good simple step.

Thanks. I will investigate the solenoid and if cleaning doesn't help, I will order a new one. Do you perhaps have a better replacement than oem?

In the attachemnt you can find a sound recording of the turbo whistle. That's a 3rd gear pull.

Time stamps of the recording:

- end of second 2: hear the whistle and it goes quiet in the middle of second 3;

- second 4: hear the whistle again;

- second 7: whistle again.

Sorry, it is not a HQ recording.

Can you explain to me what would cause the excessive crank pressure, what damage to the engine do you mean would affect high pressure?

Sorry, I can't tell what's happening from the sound specifically, but it may be the bypass valve opening if you have one.

Is the throttle plate moving to help control boost when this happens?

If cleaning the solenoid does fix things, expect to need to replace it because cleaning an old one is usually a pretty temporary fix. If needed I'd get another stock one since the car is stock.