[FHE92]

Hi All,

I have been monitoring some parameters on the Carly app but I am not sure which if any relate to Boost pressure, here are some number I got with WOT:

Boost pressure set point = 1400 Hpa
Air Pressure = 1199 Hpa
Wastegate = 0-25% but at idle it is 50% closed (shouldn't it be 100%)

Am I reading these correctly, how does one identify their boost pressure?

Any other parameters in the Carly app I should be looking at?

Also, a slightly different issue, the battery charging % is always at 27.73% and hardly moves - is this reliable does it mean my AGM battery is only 1/4 charged?

Cheers!

[djgandy]

1400hpa = 1.4 bar.
It says air pressure is 1.199 bar, which i'd say is wrong (Pressure is usually around 1 bar)
So it looks like you have 0.2 bar of boost which is 3 psi, but I'd guess that you actually have 0.4 bar of boost (6 psi)

[FHE92]

Originally Posted by djgandy

1400hpa = 1.4 bar.
It says air pressure is 1.199 bar, which i'd say is wrong (Pressure is usually around 1 bar)
So it looks like you have 0.2 bar of boost which is 3 psi, but I'd guess that you actually have 0.4 bar of boost (6 psi)

It seems though that this air pressure varies, it behaves like boost pressure as in it goes up as I get onto the throttle.

Yes ambient pressure reads 102Kpa or 1020Hpa.

3 psi is low no? when do people get the low boost error code? when there is no boost at all?

So to calculate boost pressure, you subtract barometric pressure from the boost pressure set point value?

It says that boost pressure set point means = "Setpoint – in the case of boost control this is requested boost pressure that the DME is targeting for a given Load" source = http://blog.protuningfreaks.com/2015...tuning-limits/

[Dann]

6/7psi is about right for a stock set up

[djgandy]

Originally Posted by FHE92

It seems though that this air pressure varies, it behaves like boost pressure as in it goes up as I get onto the throttle.

Yes ambient pressure reads 102Kpa or 1020Hpa.

3 psi is low no? when do people get the low boost error code? when there is no boost at all?

So to calculate boost pressure, you subtract barometric pressure from the boost pressure set point value?

It says that boost pressure set point means = "Setpoint – in the case of boost control this is requested boost pressure that the DME is targeting for a given Load" source = http://blog.protuningfreaks.com/2015...tuning-limits/

It's hard to say without knowing what's actually being reported for sure.

From what you have said so far it is targeting 0.4 bar (6psi) but it's only getting 0.2 bar assuming air pressure is pressure before throttle.

How are you measuring this though? You need to hold a long pull at 3000+RPM to get full boost.

Boost is in addition to atmospheric pressure. So the calculation is atmospheric pressure + boost = air pressure.

[FHE92]

Originally Posted by djgandy

It's hard to say without knowing what's actually being reported for sure.

From what you have said so far it is targeting 0.4 bar (6psi) but it's only getting 0.2 bar assuming air pressure is pressure before throttle.

How are you measuring this though? You need to hold a long pull at 3000+RPM to get full boost.

Boost is in addition to atmospheric pressure. So the calculation is atmospheric pressure + boost = air pressure.

I will do a run today and check back.

It looks like the air pressure is the actual (rather than requested) total pressure (as you said, boost + atmospheric).

Thanks

[FHE92]

Anyone using the carly app to have a look at % battery charge?

[FHE92]

I had another go today and this boost pressure set point doesnt go beyond 1500 Hpa and the air pressure stays max 1199 Hpa 3/4th full wot up to 6k rpm.

The fact that the wastegates are open at idle could mean there's a vacuum leak???

The car on idle when listening from the engine bay sound like the rpm goes high for a couple of second then drops slightly then repeat. It sounds the same as if someone was pinching a vacuum line briefly altering rpm.

No codes though

[djgandy]

1500 hpa is fine. 0.5 bar = 7.25 psi which is stock boost or thereabouts.

At idle the turbos are off. If there is no vaccum the wastegates will be fully open by design. But the programming of these cars to reduce wastegate rattle holds the waste gates at certain positions to reduce the chatter. Ideally they should just be closed so that boost builds quickly, but this can cause rattle so BMW's fix was to change the default wastegate position.

If you are really think you are under boosting find a steep hill, get some passengers and go WOT up it in 4th.

Are you running JB4 or anything similar?

[FHE92]

Originally Posted by djgandy

1500 hpa is fine. 0.5 bar = 7.25 psi which is stock boost or thereabouts.

At idle the turbos are off. If there is no vaccum the wastegates will be fully open by design. But the programming of these cars to reduce wastegate rattle holds the waste gates at certain positions to reduce the chatter. Ideally they should just be closed so that boost builds quickly, but this can cause rattle so BMW's fix was to change the default wastegate position.

If you are really think you are under boosting find a steep hill, get some passengers and go WOT up it in 4th.

Are you running JB4 or anything similar?

Nope completely stock, isnt boost set point the requested boost pressure from the DME rather than actual which will nearly always be lower?

The wastegates both sit at around 52% at idle and only open further from there. When I put my foot down the car jerks forward (as if it will go super accelerate) but for a split second holds back then continues accelerating sort of like a lurching effect. The only way I dont get this if i gradually increase the throttle. I can never WOT smoothly.

What if there was less vacuum (small leak) could this not leave a wastegate that is normally closed at idle partially open? Im not sure if BMW did this fix on this car but is this where set the fix at? 50% open at idle

[djgandy]

Originally Posted by FHE92

Nope completely stock, isnt boost set point the requested boost pressure from the DME rather than actual which will nearly always be lower?

The wastegates both sit at around 52% at idle and only open further from there. When I put my foot down the car jerks forward (as if it will go super accelerate) but for a split second holds back then continues accelerating sort of like a lurching effect. The only way I dont get this if i gradually increase the throttle. I can never WOT smoothly.

What if there was less vacuum (small leak) could this not leave a wastegate that is normally closed at idle partially open? Im not sure if BMW did this fix on this car but is this where set the fix at? 50% open at idle

Yes it is, hence 7.25 PSI of boost is the point it's aiming for.
You may have a vacuum leak. Hard to say really. Take it up to A1BN, old grey steve has seen enough of these goddamn things to have a good intuition.

The default wastegate position shouldn't affect your WOT boost, just your lag. Is wastegate position measured accurately? i.e. is it at the wastegate rather than the "intended" position?

If its accurate and you're not getting full shut on WOT then you probably have a leak.

[FHE92]

Originally Posted by djgandy

Yes it is, hence 7.25 PSI of boost is the point it's aiming for.
You may have a vacuum leak. Hard to say really. Take it up to A1BN, old grey steve has seen enough of these goddamn things to have a good intuition.

The default wastegate position shouldn't affect your WOT boost, just your lag. Is wastegate position measured accurately? i.e. is it at the wastegate rather than the "intended" position?

If its accurate and you're not getting full shut on WOT then you probably have a leak.

Well I am measuring the wastegate position via the carly app. I will connect INPA up and monitor the values through there and see if this makes any difference. The only code I have is 2AAF which is for the fuel pump.

I took it into BMW as I have warranty and they replaced the boost solenoid and fuel pump regulator so the other code 29f3 went but 2AAF remained.

Maybe its the fuel pump, I did check this to, normally at 92% idle and cruising but 99% at full WOT. I have seen it drop to 50% occasionally (random times) but mostly on idle.

Thank you for your help

[FHE92]

So, after another run but this time with INPA monitoring the car in place of carly.

I was looking at Saugrohrdruck (Intake manifold pressure).

So at idle i am 350-450 Hpa and at 3rd and 4th gear pulls 5k+ rpm = max 1199 Hpa not even 1200 Hpa. LOL

This is the same result I got with carly for "air pressure" so gauge pressure = 200Hpa = 0.2 bar = 3Psi.

I am only getting 3psi of boost according to INPA.

When I say it doesn't budge I mean literally I am flooring it and it will not go past 1200 Hpa.

When does the 30FF low boost code come up? Do I have to have less than 3psi?

Unusual.....

[djgandy]

Originally Posted by FHE92

I was looking at Saugrohrdruck (Intake manifold pressure).

From memory I don't think you are looking at the right thing. Saugrohrdruck doesn't sound right. I'm pretty sure it's something like "Druck vor Drosselklappe"! which translates to pressure before throttle.

Also getting a 30FF can be quite hard if you're only underboosting a little. It usually takes 10 seconds or so to appear, which is a f'ing long pull! I mean with a JB4 installed you can be doing 140mph in that time!

[FHE92]

Originally Posted by djgandy

From memory I don't think you are looking at the right thing. Saugrohrdruck doesn't sound right. I'm pretty sure it's something like "Druck vor Drosselklappe"! which translates to pressure before throttle.

Also getting a 30FF can be quite hard if you're only underboosting a little. It usually takes 10 seconds or so to appear, which is a f'ing long pull! I mean with a JB4 installed you can be doing 140mph in that time!

Saugrohrdruck translates to intake manifold pressure in google translate so it must be absolute pressure.

Not sure what to think really

[djgandy]

This is what a 30FF looks like.

[djgandy]

Here's a better one. Where the boost is actually existent. 1360hpa, which isn't bad but still under target.

See it is under "Druck vor Drosselklappe"

[FHE92]

Thanks what analog measuring blocks could I monitor this?

[Dann]

If your not happy with the car force a 30ff by unplugging the vacuum hoses.
That will open the WG right open and you will get no boost at all.
That might be a way to get BMW to take the issue seriously

[FHE92]

Originally Posted by Dann

If your not happy with the car force a 30ff by unplugging the vacuum hoses.
That will open the WG right open and you will get no boost at all.
That might be a way to get BMW to take the issue seriously

I like your thinking

[djgandy]

Originally Posted by Dann

If your not happy with the car force a 30ff by unplugging the vacuum hoses.
That will open the WG right open and you will get no boost at all.
That might be a way to get BMW to take the issue seriously

You can do this, but if there is no issue you will be wasting your time. They'll replace the vacuum system maybe,.

If there is really a lack of boost the power loss is noticeable and should trigger a code.

[FHE92]

Originally Posted by djgandy

You can do this, but if there is no issue you will be wasting your time. They'll replace the vacuum system maybe,.

If there is really a lack of boost the power loss is noticeable and should trigger a code.

No worries, Ill just keep my eye on it. As you said if it getting worse then it should fail in the near future.

Cheers

FHE92