[Chris050999]

My 328i is not hitting its boost targets.
Bootmod3 LOG

Where do I start? This is my first turbocharged engine, and I am unfamiliar with it.
Seeing as im able to build up to 1 psi under target before it starts dropping, surely its just a small leak?

I was told to check the vacuum lines pressure, which would give me the ability to rule out certain parts based on the vacuum. Is this relevant on the n20 engine?
Perhaps im completely off and theres an obvious reason as to why im not reaching target boost, please take a look at the log and give me some feedback

I am still running stock chargepipe on 21.5PSI boost, could it possibly have bursted? I do not have any fault codes.

Thanks in advance.


Edit:

The basic theory from tuners in the VW community was that the OEM diverter valves are built with a spring and plastic shroud which are only designed to hold factory levels of boost. Once tuned, the increase in boost pressure may force the OEM valve to open, bleeding boost at full throttle.

Could this possibly be what im experiencing? Is there an easy way to test solenoid controlled diverter valves?

[sspade]

Start with inspecting the complete induction tract including seals. All made of plastic from factory.

Five pieces essentially:

Intercooler

Diverter valve*

Charge side pipe

Turbo side pipe

Turbo inlet pipe



*not pictured

[andino]

You should do a pressure test to see where things are leaking. It'll be the fastest and more effective way to figure out where the leak is happening.

[meltbox]

Hrmm. No associated noises of any sort? No codes?

[Chris050999]

Originally Posted by meltbox

Hrmm. No associated noises of any sort? No codes?

No noise. Atleast nothing that can be heard over the engine noise.
I've got no fault codes, but I wasnt expecting any either, as the tune would override them.

I find it odd how im able to reach ~19 psi, but not able to hold it.

Perhaps someone could do a 101 on turbo systems as I cant imagine the reasoning behind this?

I deal with pressure testing daily, and if im able to reach 19psi, then it should have no problem holding it, seeing as the same amount of air is being "pumped" in, even if there was a leak.

The curves shown in the log look like the air is being "pumped" to 19 psi before it stops and allows it to leak off, until I change gear and its "pumped" back up.

Could this possibly be a tune issue? Wastegate control? I've sent the logs over to the tuner to ask for a clarification.

[MilanF30]

Boost drops with RPM, that's normal, happens on every turbo, just by different amount depending on turbo construction. My log looks similar, and I already asked this on PTF support site. They told me that's normal, and if I had a leak Wastegate Duty Cycle would be high:

"If wastegate duty cycle goes 100% at WOT you have a leak, wastegate duty cycle is for how much the turbo pushes to build pressure. I checked logs, looks fine."

this was their response

But since you already asked, please let us know what they said.
Your car has Pneumatic wastegate? I would say so judging by wastegate duty cycle curve...

[Chris050999]

Originally Posted by MilanF30

Boost drops with RPM, that's normal, happens on every turbo, just by different amount depending on turbo construction. My log looks similar, and I already asked this on PTF support site. They told me that's normal, and if I had a leak Wastegate Duty Cycle would be high:

"If wastegate duty cycle goes 100% at WOT you have a leak, wastegate duty cycle is for how much the turbo pushes to build pressure. I checked logs, looks fine."

this was their response

But since you already asked, please let us know what they said.
Your car has Pneumatic wastegate? I would say so judging by wastegate duty cycle curve...

Thanks, this seems to be case.
My tuner said the same thing, that my logs appear normal seeing as I have a pneumatic wastegate.

I find it odd that I have significantly more lag now than earlier, but I suppose it is nothing to worry about yet. My wastegate duty cycle seems to stay around 50% at WOT, and peaks at 65.

[MilanF30]

Yes, that's what i thought. My WDC is doing the same.
Although I don't have more lag than before, even less... Did you changed the Intercoller?

[Chris050999]

Originally Posted by MilanF30

Yes, that's what i thought. My WDC is doing the same.
Although I don't have more lag than before, even less... Did you changed the Intercoller?

No, running stock intercooler.
Currently 0 - 5 celsius here, and i've coded the thermostat to open earlier. Going to change it back to stock as im still at stock temperatures, even with the stage 2 tune under hard load.
I do not feel like the 800€ investment for an ever so slightly bigger intercooler is necessary.

[meltbox]

Yea your wastegate duty cycle makes no sense to me. Is that how the pneumatic acts?

EDIT: I don't see any clear correlation of what is going on here. The MAF even shows decreasing flow high up in 4th gear. Kind of odd. I guess I would start by taking apart intake, inspect turbo shaft for play, then reassemble intake with a little bit of silicon grease on joints? It really doesn't take long to do.

[MilanF30]

This is how pneumatic WG acts... mine is doing the same. See here

Although now that you mentioned MAF, mine is acting a bit differently, no such drop with rpm's. Some drop is to be expected in high rpm's because turbo is small and not very efficient in high rpm's...

[Chris050999]

Originally Posted by meltbox

Yea your wastegate duty cycle makes no sense to me. Is that how the pneumatic acts?

EDIT: I don't see any clear correlation of what is going on here. The MAF even shows decreasing flow high up in 4th gear. Kind of odd. I guess I would start by taking apart intake, inspect turbo shaft for play, then reassemble intake with a little bit of silicon grease on joints? It really doesn't take long to do.

I'm not sure if I quite agree on the MAF showing odd signs, but I will lube the joints and clean the sensor, see if it changes anything. Easily done=)

[meltbox]

The MAF isn't horribly off but its just didn't seem right to me. I could be wrong though. Curious to hear if sealing up the intake helps at all or if the log looks any different after.

EDIT: On the other hand if MAF was misreading the DME should get sort of unhappy about AFRs. Especially since your STFT is dead on. Is your LTFT around 1 as well?

[meltbox]

Originally Posted by MilanF30

This is how pneumatic WG acts... mine is doing the same. See here

Although now that you mentioned MAF, mine is acting a bit differently, no such drop with rpm's. Some drop is to be expected in high rpm's because turbo is small and not very efficient in high rpm's...

Thats very interesting....

Also MAF dropping wouldn't usually be a boost leak. A boost leak would drop PSI but intuition tells me increase flow. I suppose the diverter valve would make sense in this case as a leaking one would lead to air being dumped into the turbo inlet reducing the need for fresh air from the intake.

Is this car an auto? A manual would also drop boost and flow on shifts.

[MilanF30]

Not sure if you asking me or Chris050999, but mine is an auto

[meltbox]

Originally Posted by MilanF30

Not sure if you asking me or Chris050999, but mine is an auto

Chris but hey the more the merrier! Someone may find this info helpful in the future.