[Davy Jordi]

Originally Posted by xcelir8bmw

Limitless? Huh? I have, for now, 7 modes of max which has a ceiling programmed not to go above it. And spikes I have are not bad and predictable. It is all about the tooling and what reads and compares to what. In stock mode I challenge you if the JB4 can do it to see what instrumentation it reads versus actual vacuum tap.

only if you buy the vacuum tap for me, mate.

do it for the x2 community's sake.

ps you're the one who holy shitted in the wrong thread about not going over 3Xpsi bc of course you don't want your engine to blow up.

[xcelir8bmw]

you obviously not understand the testing

reread

the holy shit was that TDI works, that is all

is it the gauge is accurate and obdii is not

what really is stock boost wot

26.5 is what I read not 22.5 obdii

then do the math

my 30 is really equiv to obdii plus 4

[xcelir8bmw]

what does BMS show in stock mode logging?

note, JB4 probably will be installed post TDI final map

hope tomorrow

and I will have all the answers myself

[rice_rocket88]

25 spike but tapering to 22.5. Sorry I'm on my phone so I can't send my screen shot. It tapers quick, and the other maps hold the higher boost for longer. I'm going to log later when I get a free chance to see if there new firmware changes things.

[xcelir8bmw]

wondering if my gauge is accurate and calibrated with base vacuum

[xcelir8bmw]

curious of BMS readings vs vacuum tap readings

[xcelir8bmw]

so many questions

JB4 going on tomorrow

[Davy Jordi]

don't nerd out too hard, xcelir8.

ps where's my boost tap?

[xcelir8bmw]

Color me impressed. USA build quality, hell yeah!

Prepping for tommorow. Want to get the lay of the land.

And OBDII cable is required and reads more than just RPM.

Just wish the fatty cable to the box was longer so I can truly stealth it.

Easy Peasy!

[billnchristy]

Every one of us has seen 22.8 with obd, I’d be surprised if that’s wrong. It also makes sense with the stock b48 making around 15. If we only make 80hp more with 10psi we’re sucking.

[Fuel-It!]

Originally Posted by xcelir8bmw

Limitless? Huh? I have, for now, 7 modes of max which has a ceiling programmed not to go above it. And spikes I have are not bad and predictable. It is all about the tooling and what reads and compares to what. In stock mode I challenge you if the JB4 can do it to see what instrumentation it reads versus actual vacuum tap.

You can't read boost via OBDII when tuned as it will read factory like boost levels regardless of actual. You need to read/sample them from your tunes bluetooth app and then plot them like the JB4 logs that have been posted here. It sounds to me like you have no idea how much boost you're actually running. And more importantly how much timing advance and what the AFR is at those boost levels.

[Fuel-It!]

Originally Posted by billnchristy

Every one of us has seen 22.8 with obd, I’d be surprised if that’s wrong. It also makes sense with the stock b48 making around 15. If we only make 80hp more with 10psi we’re sucking.

The 2.5bar manifold sensor caps out around 22psi, but the pre-throttle sensor is actually 4bar. Sounds to me like the OBDII PID you're all using for boost is reading the wrong sensor.

[Davy Jordi]

so i woke up to an email from terry to reduce the max psi on map 2 to 27 from 31.5 where it was defaulted at after i sent in my first logged run.

i did so and that's in line with 4psi over stock at max boost as is advertised. i don't quite understand why it doesn't come out of the box that way, but in either case i changed it and am awaiting a bit more clarification.

[rice_rocket88]

Originally Posted by Fuel-It!

The 2.5bar manifold sensor caps out around 22psi, but the pre-throttle sensor is actually 4bar. Sounds to me like the OBDII PID you're all using for boost is reading the wrong sensor.

This is pretty neat to know.. we're all talking about using our own plug in obdii sensors in which I don't think I have an option for a different boost sensor as read. I might have to go look again if there are other options which would be good. Do you know if jb4 reads this, or does it run a correction value?

As for your comment to excilr8bmw .. He's physically tapped the sensor with an aftermarket boost gauge to read raw boost in the system, which is why he wants to compare readouts from that sensor when using the tdi box, and now with the jb4.

[rice_rocket88]

Originally Posted by Fuel-It!

Yes that all makes sense, load up the v18 BETA firmware from the app to enable the boost safety with no OBDII. Record a short log manually at idle with that firmware also and post or email that in so they can check your boost scaling.

Second try after work flashed fine, and a different behavior (when I flashed in the morning, the hazards would blink every few seconds and this time it did not). Terry said my boost scaling was fine and to relog map 6. My map 6 was scrambled from the failed relay so I had to get more help from Terry to set it back to default ( missing one line that wasn't listed on his forum post for default settings). I haven't had a chance to go back outside it was raining yesterday. I don't expect much to change since the beta firmware didn't list revisions that would apply, but I can always hope!

[//TMT]

Originally Posted by Fuel-It!

The 2.5bar manifold sensor caps out around 22psi, but the pre-throttle sensor is actually 4bar. Sounds to me like the OBDII PID you're all using for boost is reading the wrong sensor.

Interesting - can you elaborate? A 2.5bar sensor should read up to 2.5bar, what limits it to 22psi?

My understanding of the 2-sensor approach is that the engine uses them because it doesn't have a bypass or blowoff valve. It uses the difference to detect overpressure situations. Right? If so, I definitely agree that we'd need to read the other PID.

[Fuel-It!]

Originally Posted by //TMT

Interesting - can you elaborate? A 2.5bar sensor should read up to 2.5bar, what limits it to 22psi?

My understanding of the 2-sensor approach is that the engine uses them because it doesn't have a bypass or blowoff valve. It uses the difference to detect overpressure situations. Right? If so, I definitely agree that we'd need to read the other PID.

They are absolute sensors so 1 bar is taken up already assuming you're living on planet Earth. This leaves 1.5bar for boost measurement or around 22psi. The actual max reading will vary based on your barometric pressure so can range from 21psi to 23psi fairly commonly. Seeing a max of 22.8psi for example would not at all be surprising.

A higher resolution sensor is used on the manifold since it spends more time in vacuum. The pre-throttle sensor provides the higher range. The problem with OBDII is it's hard-coded to the manifold sensor.

The JB4 reads both sensors and outputs both sensor values in logs.

[billnchristy]

We actually do have a bov and I can hear it now with my intake

[rice_rocket88]

We do have one, but it's routed right to the intake side of the turbo so close that you don't hear much flutter or sound. The picture you have is a little misleading.. on the new tis breakdown it shows that the "nipple" in your picture is actually an electronic plug. It's probably super efficient but it's now all built in one piece of the turbo making it more expensive I would say since it's all electronic vs mechanically controlled as in the past.

https://www.newtis.info/tisv2/a/en/f...lve/1Vnc3euAo8

[Will Pwr]

Originally Posted by rice_rocket88

We do have one, but it's routed right to the intake side of the turbo so close that you don't hear much flutter or sound. The picture you have is a little misleading.. on the new tis breakdown it shows that the "nipple" in your picture is actually an electronic plug. It's probably super efficient but it's now all built in one piece of the turbo making it more expensive I would say since it's all electronic vs mechanically controlled as in the past.

https://www.newtis.info/tisv2/a/en/f...lve/1Vnc3euAo8

Aside from the efficiency aspect, part of it is related to emissions requirements to keep it a closed-loop system. With this design it doesn't really allow one to vent the compressed air to atmosphere, let alone be able to use an aftermarket/performance unit. I guess technically you still could, but you would need to bypass the operation of the factory one for it to even be functional. However, given the size/cfm of the stock turbo, I don't think it would be worthwhile from a performance standpoint...though from an audiable standpoint that's a different story.

[//TMT]

Originally Posted by Fuel-It!

They are absolute sensors so 1 bar is taken up already assuming you're living on planet Earth. This leaves 1.5bar for boost measurement or around 22psi. The actual max reading will vary based on your barometric pressure so can range from 21psi to 23psi fairly commonly. Seeing a max of 22.8psi for example would not at all be surprising.

A higher resolution sensor is used on the manifold since it spends more time in vacuum. The pre-throttle sensor provides the higher range.

Aha - yep, agreed. So 2.5bar manifold sensor measuring 22psi of boost. Absolute vs relative, got it.

I guess the sensor was chosen for its sensitivity. It is certainly an interesting difference to the other one.

The problem with OBDII is it's hard-coded to the manifold sensor.

The JB4 reads both sensors

Indeed. As does the DME of course.

[//TMT]

Originally Posted by rice_rocket88

We do have one, but it's routed right to the intake side of the turbo so close that you don't hear much flutter or sound. The picture you have is a little misleading.. on the new tis breakdown it shows that the "nipple" in your picture is actually an electronic plug. It's probably super efficient but it's now all built in one piece of the turbo making it more expensive I would say since it's all electronic vs mechanically controlled as in the past.

https://www.newtis.info/tisv2/a/en/f...lve/1Vnc3euAo8

Ok I stand semi-corrected. That link has good information thanks.

But note, it's actually a "bypass valve", it sends the boost back to the turbo instead of venting to the air as a true blowoff does. This is both more efficient, and less polluting, as the air metering is always perfectly accurate.

There is nothing new about turbo-integrated compressor bypass valves. They've been around for decades. What's different here is that it's electrically controlled, as is the wastegate. In earlier designs, a vacuum line is used to actuate the CBV, and a turbo control valve is pulsed to control the wastegate. Moving these functions to direct servo control really ups the game for the engine control designer, and ups the challenge for the JB4 too.

Bill, what is the sound like when you hear the valve opening? In my Volvo (vacuum actuated) it makes a kind of guttural flutter/ahem sound. It's quite subtle, actually.