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      10-22-2010, 08:37 PM   #1
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Speed density? Load site? Questions inside...

Hello all, my name is Brandon and I recently picked up an E90 335xi 6MT, and was trying to learn a little bit about how our ECU's work. To give a bit of background, I've owned a 09 G37, 06 STI, 06 MS6, 04 WRX, 03 350Z, 91 Toyota MR2 turbo & a 2nd gen DSM, most all of which were at some point self tuned. I also have to admit I am a little bummed out to see that no one has really hacked these ECU's (sans major tuners) and made some sort of open source tuning software accessible, as these cars seem to have a large enough following. I guess I'm just spoiled from spending too many years in the Subaru community where the majority of tuning is done via OS/OpenECU (free downloadable tuning software) these days, and the only things really necessary are a Tactrix cable (cable that goes from USB to OBDII port), datalogging software (typically free/RomRaider) and a WBO2 sensor of some sort.

I digress, the question I was trying to find an answer to is, what kind of load site do these cars use from the factory? I didn't see any sort of MAF sensor, so I'm assuming they're not MAF based... I did notice they have a MAP sensor (maybe a TMAP?), so I'm just making an assumption, but are they running speed density? I'm only talking Open Loop, as I'm assuming Closed Loop is like most other cars, just referencing a NBO2 or WBO2 to try and hit stoich AFR (14.7:1).

If they're running some sort of SD based tuning/load site, how is boost being controlled without bypassing the BCS with a piggyback/chip? I'm assuming most piggyback/chips are somehow manipulating the MAP sensor in order to raise the boost, correct? If so, is the piggyback/chip also merely raising the OL IDC's a set amount to compensate?

Sorry to ask so many questions, I'm just really curious as to how these motors operate.

Thanks in advance!

-B
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      10-22-2010, 08:43 PM   #2
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TMAP for N54 engines and MAF for N55 engines.

Also, the BMW ECUs have high end encryption compared to other units. So its almost impossible to a mom-and-pop garage self-tuning deal that you are interested in..
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      10-22-2010, 08:45 PM   #3
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Lots of folks from Denver area out in this section of the forum FYI...

http://www.e90post.com/forums/forumdisplay.php?f=49
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      10-22-2010, 08:54 PM   #4
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Quote:
Originally Posted by vasillalov View Post
TMAP for N54 engines and MAF for N55 engines.

Also, the BMW ECUs have high end encryption compared to other units. So its almost impossible to a mom-and-pop garage self-tuning deal that you are interested in..
Thanks for the info, kind of interesting they switched over to running a MAF for the newer N55 motors.

Although when the Subaru/Mitsubishi people hacked their ECU's, it wasn't just 1 or 2 people here and there from what I understand, it was a fairly large group collaboration that spawned sites like openecu.org and romraider.com. While I'm sure it's no walk in the park (I sure as hell wouldn't know where to start! haha), with the amount of popularity these cars have built up, I'm just shocked no one has started anything of a similar nature.
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      10-22-2010, 08:55 PM   #5
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Originally Posted by forza1976 View Post
Lots of folks from Denver area out in this section of the forum FYI...

http://www.e90post.com/forums/forumdisplay.php?f=49

Yeah, I noticed that and posted up in the Dyno Day thread earlier
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      10-23-2010, 01:04 AM   #6
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afaik the n54 and n55 run close loop 100% of the time.

if a car only has a map sensor then afaik it is always speed density.

you will be surprised to find that the n54 runs stoich well into peak torque in stock tuning config.

Last edited by mwahlert; 12-07-2010 at 08:21 AM..
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      10-23-2010, 01:05 PM   #7
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Quote:
Originally Posted by mwahlert View Post
afaik the n54 and n55 run open loop 100% of the time.

if a car only has a map sensor then afaik it is always speed density.

you will be surprised to find that the n54 runs stoich well into peak torque in stock tuning config.
Wow, and there's no knock/detonation? That's nuts! I suppose I would love to see a log that displayed knock count as well.
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      10-24-2010, 03:48 PM   #8
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He meant closed loop 100% of the time, lol. And yeah, a big push from a crew of engineers would be great...but it frankly requires the right minds working on the cars. And since the new fad amongst manufacturers seems to be working their damndest to keep people out of the ECU instead of trying to improve the quality of their products, I think there is less incentive for people to crack them. FWIW, if you want to DIY tune, the CP-e Standback 2 is a good option...just isn't free, that's all.
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      10-24-2010, 05:21 PM   #9
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Quote:
Originally Posted by DefactoM6 View Post
He meant closed loop 100% of the time, lol. And yeah, a big push from a crew of engineers would be great...but it frankly requires the right minds working on the cars. And since the new fad amongst manufacturers seems to be working their damndest to keep people out of the ECU instead of trying to improve the quality of their products, I think there is less incentive for people to crack them. FWIW, if you want to DIY tune, the CP-e Standback 2 is a good option...just isn't free, that's all.
I actually have a bit of experience with the Standback (original) from the time I spent in the Mazdaspeed community (I was an admin for a local Mazda forum/club when I owned my Mazdaspeed 6), and played with a couple of them on MS3's. I've always liked CP-E as a company, they have a good bit of innovation, and I just might look into getting a Standback for my 335xi in the future... it's just too bad it's not the most cost effective option compared to the communities I've been involved in.
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      10-24-2010, 06:09 PM   #10
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Quote:
Originally Posted by DefactoM6 View Post
And since the new fad amongst manufacturers seems to be working their damndest to keep people out of the ECU instead of trying to improve the quality of their products,


Unfortunately it does seem to be the case.
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      10-25-2010, 09:35 AM   #11
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Quote:
Originally Posted by roninsoldier83 View Post
I actually have a bit of experience with the Standback (original) from the time I spent in the Mazdaspeed community (I was an admin for a local Mazda forum/club when I owned my Mazdaspeed 6), and played with a couple of them on MS3's. I've always liked CP-E as a company, they have a good bit of innovation, and I just might look into getting a Standback for my 335xi in the future... it's just too bad it's not the most cost effective option compared to the communities I've been involved in.
Yup, unfortunately the tuning platforms aren't cheap. I do think that once an effective fueling solution is reached for these cars, more tuning options will practically explode onto the scene, since the big turbo upgrades will follow almost immediately.

Quote:
Originally Posted by scalbert View Post


Unfortunately it does seem to be the case.
And the sad part is, at least where I come from, the way to increase your sales is by improving your product (or lowering prices). The ROI for a redesigned fuel pump (come on, they're still selling brand new cars with them!) would be WAY higher than continually working to keep people other than BMW NA out of the ECU.
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      10-25-2010, 09:52 AM   #12
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The n54/n55 run closes loop fuel control at all times (except) for deccel. If you look hard, you can find ROM editing/flashing hardware. The pricing isn't cheap. But even if it was, the real issue is that the read/write flashing process takes over 45min and requires an external stable power supply. Unlike evo/Subaru which can be done in less than 2min with the radio on in a Starbucks drive-thru. It's also pretty evident that BMW jumbles the ROM contents around periodically to hinder aftermarket ROM editing. And that only a handful of tables seem to be understood. Which is a far cry from Evo openecu that has stand-alone like functionality and proper meth integration capability.
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      10-25-2010, 10:50 AM   #13
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Originally Posted by shiv@vishnu View Post
The n54/n55 run closes loop fuel control at all times (except) for deccel. If you look hard, you can find ROM editing/flashing hardware. The pricing isn't cheap. But even if it was, the real issue is that the read/write flashing process takes over 45min and requires an external stable power supply. Unlike evo/Subaru which can be done in less than 2min with the radio on in a Starbucks drive-thru. It's also pretty evident that BMW jumbles the ROM contents around periodically to hinder aftermarket ROM editing. And that only a handful of tables seem to be understood. Which is a far cry from Evo openecu that has stand-alone like functionality and proper meth integration capability.
Wow Shiv, thanks for the information! Piggyback it is haha.

Shiv, I have a question for you, you've been tuning turbo cars for a long time (of course coming from the Subaru community, your reputation precedes you & I actually used to run a Vishnu TBE & up-pipe on my old '04 WRX years ago when you guys used to make divorced wastegate DP's for them), so you would be a tuner I would trust. I'm still learning about these N54 motors, have looked at a few dyno graphs, and am wondering how these things don't knock/detonate with some of the uber-lean AFR's they seem to hold under full load?

It seems most of the dyno's I've looked at that has AFR's posted showed these motors holding stoich AFR's under full load/boost until around ~4000rpms, and even then they don't taper too much (most appear in the 12-13:1 range towards redline it seems)... now, I understand that DI has awesome cooling properties that can help stave off detonation, but with a 10.2:1 compression ratio & boosted, it seems pretty damn lean to say the least. I haven't had a chance to look at any logs, but most of the charts look pretty smooth, with no dips, so it doesn't look like they're knocking and pulling timing to compensate... I'm a little baffled?!?

My only assumption is that since I think I read they don't control load with a throttle body, but with fuel (more like a diesel?!?) that the spray pattern & timing is precise enough to fire directly at the plug during spark with no overlap, or something to that effect?!? Any insight you can share would be awesome

Either way, thanks for chiming in Shiv!
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      10-25-2010, 11:04 AM   #14
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Quote:
Originally Posted by shiv@vishnu View Post
The n54/n55 run closes loop fuel control at all times (except) for deccel. If you look hard, you can find ROM editing/flashing hardware. The pricing isn't cheap. But even if it was, the real issue is that the read/write flashing process takes over 45min and requires an external stable power supply. Unlike evo/Subaru which can be done in less than 2min with the radio on in a Starbucks drive-thru. It's also pretty evident that BMW jumbles the ROM contents around periodically to hinder aftermarket ROM editing. And that only a handful of tables seem to be understood. Which is a far cry from Evo openecu that has stand-alone like functionality and proper meth integration capability.
The tool I use to read / write the N54 takes around 75 minutes to read the ECU and 20 to write it. Not like an S54 which takes around 5 minutes to read/write.
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      10-25-2010, 02:04 PM   #15
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The tool I use to read / write the N54 takes around 75 minutes to read the ECU and 20 to write it. Not like an S54 which takes around 5 minutes to read/write.
Are you Mark D'Sylva? If so, didn't know you were experimenting with these cars in addition to the older stuff...
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      10-25-2010, 02:09 PM   #16
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Quote:
Originally Posted by roninsoldier83 View Post
Wow Shiv, thanks for the information! Piggyback it is haha.

Shiv, I have a question for you, you've been tuning turbo cars for a long time (of course coming from the Subaru community, your reputation precedes you & I actually used to run a Vishnu TBE & up-pipe on my old '04 WRX years ago when you guys used to make divorced wastegate DP's for them), so you would be a tuner I would trust. I'm still learning about these N54 motors, have looked at a few dyno graphs, and am wondering how these things don't knock/detonate with some of the uber-lean AFR's they seem to hold under full load?

It seems most of the dyno's I've looked at that has AFR's posted showed these motors holding stoich AFR's under full load/boost until around ~4000rpms, and even then they don't taper too much (most appear in the 12-13:1 range towards redline it seems)... now, I understand that DI has awesome cooling properties that can help stave off detonation, but with a 10.2:1 compression ratio & boosted, it seems pretty damn lean to say the least. I haven't had a chance to look at any logs, but most of the charts look pretty smooth, with no dips, so it doesn't look like they're knocking and pulling timing to compensate... I'm a little baffled?!?

My only assumption is that since I think I read they don't control load with a throttle body, but with fuel (more like a diesel?!?) that the spray pattern & timing is precise enough to fire directly at the plug during spark with no overlap, or something to that effect?!? Any insight you can share would be awesome

Either way, thanks for chiming in Shiv!
No problem man. Nice to have you on this forum To answer your question about AFR, you will naturally see much leaner AFR targets with this Direct Injection engine than you will with conventional injection EJ25s and 4G engines. Seeing these engines target close to stoich at peak torque is perfectly normal. Running them richer just increases fuel consumption and doesn't to a thing for knock resistance or EGT. Running them richer, as engine speed goes up, is normal as well since the time between injection events is reduced and the cooling effects of DI somewhat diminished. You're really enjoy tuning this engine. It's like a whole new box of chocolates
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      10-25-2010, 04:43 PM   #17
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Quote:
Originally Posted by shiv@vishnu View Post
No problem man. Nice to have you on this forum To answer your question about AFR, you will naturally see much leaner AFR targets with this Direct Injection engine than you will with conventional injection EJ25s and 4G engines. Seeing these engines target close to stoich at peak torque is perfectly normal. Running them richer just increases fuel consumption and doesn't to a thing for knock resistance or EGT. Running them richer, as engine speed goes up, is normal as well since the time between injection events is reduced and the cooling effects of DI somewhat diminished. You're really enjoy tuning this engine. It's like a whole new box of chocolates
Wow.... running then richer than stoich under load doesn't even decrease EGT's, that's nuts! I think you're right, I think I'm going to enjoy this engine

Thanks again for the info Shiv!!
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      10-25-2010, 08:35 PM   #18
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Shiv please get your hands on an XI and figure out how to get RWD mode!
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      10-25-2010, 10:26 PM   #19
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Quote:
Originally Posted by DefactoM6 View Post
Are you Mark D'Sylva? If so, didn't know you were experimenting with these cars in addition to the older stuff...
Yes I am. I have to keep moving forward, can't live in the past! I was also involved in developing software for what I figure was the first s54 transplant into another car, back in 2005. I posted about that on another forum 5 years ago. I guess that is finally getting more common.


Here is a link to a video of a 2.1L M44 I tuned some years back:


I've got 5 N54 powered cars running in Toronto, one of them came in 3rd in GT class in Targa Newfoundland this year.

Last edited by MarkD; 10-26-2010 at 11:32 AM..
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      12-06-2010, 10:57 PM   #20
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Wanted to bump this thread, cause I was asked a question I couldn't answer today.

How does the N54 sense load?

It's been asked a couple times above but never answered
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      12-06-2010, 11:08 PM   #21
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There is some great info in this thread. Tuning, especially with this engine/ECU, is always intriguing.
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      12-07-2010, 07:54 AM   #22
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How does the N54 sense load?
Under heavy load, the TMAP, boost and IAT, and then the DME runs some calculations. Under light load the manifold pressure sensor is used.
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