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Discussion Starter #1
Hi Guys,

I currently drive an N52 engined 2006 2.5i Z4 with the 177bhp engine. Now all of the engine, ECU, exhaust etc. components are identical between the 177bhp 2.5i and the 214bhp 2.5si (also found in the 325i), therefore it appears the 177bhp model is simply detuned via the software.

I've got a well known remapping specialist who's going to compare the software differences for me for the stock 2.5i and 2.5si to see where the extra power comes from (possibly something encrypted on the ECU).

Now he's having abit of trouble identifying the base 2.5si/325i software from the BMW disc - due to the amount of different engines which use the same siemens ECU. Therefore I require the software code for the 214bhp N52 engine, it's located on a sticker on the ECU. The sticker has your VIN/chassis number and three 7 digit codes, I don't need the vin number, just the three 7 digit numbers after it. I've circled the sticker here (The ECU in the photo is no good as it from a US 325i which is actually a 3.0)...



If anybody can have a look at their ECU and get this for me it would be much appreciated.

£20 beer money via paypal aswell for your efforts! :)

On my Z4 with the same engine (albeit the 177bhp model) the ECU isn't hard to get to. Assuming it's the same for the 3 series then it's located under a black cover at the back of the engine bay on the passenger side. This is held down with 4 torx screws and under this is a load of wires and a smaller black cover, this unclips revealing the ECU, which then slides out enough to read the numbers on the stickers. Nothing needs unplugging etc. Should take about 10mins in total. I've circled the ECU location here...



I've tried asking on the Z4 forum however there isn't that many 2.5si Z4's around so had no luck as of yet.

Cheers :).
 

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i would of thought some kind of simple inlet manifold restriction aswell to curb the power i can't see a normally aspirated being soley detuned electronically..
 

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Discussion Starter #3
That's what I thought initially. On the USA n52 engined 3.0i (with around 215bhp - we didn't get this model in the uk I don't think) and 3.0si (260bhp) the extra power comes from a three stage inlet manifold and mapping to suit, however this manifold is already present on the uk 2.5i, and part numbers for the 2.5i and 2.5si inlet manifold are the same too.
 

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want to restrict a car that much surely ya have to strangle its capacity to breathe aswell...

i found this on the 3 litre version which makes sense to me..

The N52B30 is available in three versions, all displacing 3.0 L (2996 cc/182 in³). However, each version produces variable maximum output depending upon the application. With a common engine displacement, the output changes result from the omission of the variable resonance system, dual plenum intake runner system, and the variable back pressure muffler: 190 kW

maybe of use to yuo i dunno..

http://www.e90post.com/forums/showthread.php?t=372973

http://www.e90post.com/forums/showthread.php?t=372973

you sure you have the correct info according to wiki the 177PS engine never came in the Z4

The N52B25 comes in two versions, both displacing 2.5 L (2497 cc/152 in³). The first produces 130 kW (174 hp) at 5800 rpm and 230 N·m (170 ft·lbf) at 3500-5000 rpm while the more powerful version is rated at 160 kW (218 hp) at 6500 rpm and 250 N·m (184 ft·lbf) at 2750-4250 rpm.

Applications:

* 130 kW (177PS/174 hp) and 230 N·m (170 ft·lbf)
o E60/E61 523i (Not in the US market) Sedan and Touring
o E90 323i (Not in the US market) Sedan

* 160 kW (218PS/215 hp) and 250 N·m (184 ft·lbf)
o E83 X3 2.5si (Not in the US market) Sports Activity Vehicle
o E85 Z4 2.5si (Not in the US market) Roadster
o E89 Z4 sDrive23i (150 kW/204 hp) (EUR)
o E60/E61 525i Sedan and Touring (US)

* 160 kW (218PS/215 hp) and 270 N·m (199 ft·lbf)
o E90/E91/E92/E93 325i (2005-2007 model years)
 

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Discussion Starter #6
Originally I thought it would be the intake manifold/exhaust, as mentioned on the e90 post forums - that's where I got the idea initially. But with the UK 2500cc versions of the N52 this doesn't seem to be the case.

Part numbers on RealOEM are as follows...

Intake manifold
2.5i = 11617559525
2.5si = 11617559525

Exhaust manifold
2.5i = 18407511674
2.5si = 18407511674

Those are just 2 examples, the list goes on!
 

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Discussion Starter #7
Yeah I'm positive I have the 177ps engine. Wiki must be wrong in that repect.

I have just had a second look at RealOEM though and there are actually two different intake manifolds listed for the 2.5i, the one with the part number listed above, and one with the last digit of the part number being a 6 instead of a 5. Both appear to be a three stage manifold (unlike the USA where the power difference stems from the i having a standard manifold and the si having a three stage). I wonder if the manifold fitted to the 2.5i is simply slightly more restrictive whilst still retaining the 'three stage' functionality?

Now to determine which exact part number the stock manifold has. Will the part number be printed on the actual manifold?
 

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prolly be stamped or moulded on it.. somewhere..

i think some of the restriction is created by limiting the valvetronic lift electronically..
 
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