N52 Swap Discussion

[nando]

There probably is a CAN message from the HVAC system to tell it when you're heating the car. There must be a way to force it to flow a minimum amount of coolant or some other way to tell it you're using the heater. I have never looked at that because nobody has ever mentioned an issue with heat, but it seems pretty important!

On the N52, it uses the electric pump itself to heat the cabin with the engine off (the "rest" function). We have full control over the DME, so I don't see why it couldn't be made to work.

[Caperix]

The bigger cars, use a aux water pump to help circulate coolant, even the e60 with a n52 has one off the upper radiator hose. It is adding a potential failure point, though most just drip when they leak. Are you using a can translator board? You would need to find what code the ihka sends to the dme but it should be doable. I know m54 z4's were available with the low ihkr HVAC system in the us, I don't know if that continued to the n52 cars but it should have much less communication involved.

[hubcapboy]

Mercedes uses the aux pump to circulate coolant and provide heat when the engine is off but still warm.

[hubcapboy]

Huh look, the Mercedes SL heater control valve I bought to experiment with relocating the valve to under the hood has an aux pump attached to it:

[hoveringuy]

I haven't had cabin heat up until now and was getting tired of cold feet, so I finally plumbed it up. Some things are different on the N52, but the primary cooling loop is basically the same. Hot coolant leaves the engine, flows through the radiator, is metered by the thermostat and then pumped back into the engine. I fabricated a small manifold to tap the engine outflow and send it to the bottom pipe of the heater core.

It absolutely sucks!

No warm air even when at operating temp at idle. I did get a small amount of hot air when I did some driving. What's going on?

As an experiment I triggered the coolant pump to 95% through INPA once I was back in the garage and got a plethora, a veritable gusher of hot air. Like, a lot!

So, I think what's happening is that the engine doesn't know that I'm trying to make heat and runs the coolant pump at low speed which isn't pushing anything through the heater core. Need either 1) an aux heater circuit circulation pump or 2) a way to tell the ECU to ramp up pump speed for heat.

[hoveringuy]

My fuel pressure was 6 psi short of 5bar, and my stock fuel pump was very noisy, so I installed a new Douchewerks DW200 with the 9-1031 install kit. This is supposed to flow 210 liters per hour at 5bar while drawing 11 amps.

For the install you're supposed to just use a hose clamp to attach it to the support rod, but I didn't think that was secure enough and added a bracket, because I love brackets. I also didn't use the supplied accordion flex line and used fuel line instead. My other hints are that the pickup was hitting the bottom of the tank if I lowered the pump all the way to the bottom, and the position of the clamp is important so that it doesn't hit the fuel transfer tube inside the tank. The filter sock was clocked to the correct position for the tank, however.

It's quieter than my stock pump and boosted the rail pressure.

[hoveringuy]

Let's talk about my weight.

Just crossed the scales at 2460lbs, with a full tank of gas and the almost exact configuration I had with the M54. That's a 23# reduction from M54 to N52. Some other things that changed are aluminum X3 brake booster (-6lbs) and 5" rear springs (-2lbs), so the N52 is around 15lbs lighter than the M54 which includes a 6speed transmission, dual-mass flywheel over the G260 single, and dope S54 headers over the OBD2 manifolds. (plus I have beefy steel engine mount arms, a steel oil pan that can double as a skid plate, and hydraulic engine mounts.)

Replacing my passenger seat with a Sparco, deleting rear interior (because I won't be able to get people back there, anyway...) and maybe a CF hood would easily get me below 2400.

[hoveringuy]

If you are eliminating the mass air flow meter, I would just pull the pins out of the harness for the intake air temp instead of spending $124 on that cable. I looks like it is a obd 1 e36 intake temp sensor they are using.

Yeah, pretty much exactly. We've ordered the $12 sensors and we'll just extend the wiring ourselves with the super-common 2 pin plug.

I would never, ever suspect that I don't have a MAF, it runs smoothly throughout.

[Caperix]

If you are eliminating the mass air flow meter, I would just pull the pins out of the harness for the intake air temp instead of spending $124 on that cable. I looks like it is a obd 1 e36 intake temp sensor they are using.

[Caperix]

The design of the mass air flow meter changed with the n52k motor & msv80 dme. BMW documentation says they went from an analog to digital air flow meter. I believe this is also when they fazed out the mass air flow meter for euro markets. That is likely the difference you are seeing in the wiring diagrams.

[hubcapboy]

Converting from MAF to euro IAT to reduce intake restriction, or is there something else I'm not aware of?

I believe that some people convert from MAF to euro IAT to incorporate what they think is a less restrictive (complete) euro intake. The rumor from nando is that the MAF operation isn't optimal anyway, and he doesn't include it in his tune (he can correct me, but that component of operation in his flashes must be based on the euro air box/euro IAT).

Since the swap flash will never read the MAF anyway, using an equivalent IAT sensor in a better location is preferable to accommodating either the euro IAT *or* the combo MAF. I don't have an airbox with the correct mounting for either of these sensors, so my celebration here is that rather than use an aftermarket pipe that accommodates a MAF like this:



I can just locate an intake air sensor anywhere that's convenient, like this:

[Bored]

This ECU fan control pleases me. I expect that this is exactly what I'm going to be doing, with an additional override after the fan control box that puts my fan on high speed when my AC compressor clicks on. I won't have any feedback issues with an override switch... the thermostat will just behave as designed.

I'm currently extending and appending a Z4 wiring harness to suit the chassis (documentation to follow) and I want to confirm what we'd previously discussed related to the MAF/IAT sensor, because I have a pin number mismatch between the connectors on the X3 and Z4 harnesses I'm combining. Here's the BMW diagram for several of the N52 engines:

Pin 4 on the connector is always sensor ground (M_HFM) and Pin 5 on the connector is always the Intake Air Temperature Signal (A_TANS). These always connect to pins 27 and 28 respectively on DME Sub-connector X60005.

Pin 1 on the connector is always the MAF signal (A_HFM), but the DME pin for that signal changes between models. *I believe* this becomes moot, because Nando's tunes specifically do not use this sensor. Looking at the last diagram, "depending on version" some e90's after 2007 have a IAT sensor that doesn't include any MAF function or wiring. Which versions? Here's one example of a part number:

13627547822

Intake air temperature sensor

From:09/01/2005To:-Weight:0.016 kgPrice:Part 13627547822 was found on the following vehicles:These are all European n52 models, but curiously not the European Z4... which kept the full sensor!

Rather than having these extra signals, grounds and power signals floating around in my harness, I'm going to pull everything but the two wires for the IAT out. Even if I left them connected, I have a 50/50 shot of knowing which pin we would send the MAF signal to based on the info above.

I don't know if power or additional grounding is required for the sensor I have to detect temperature, but I think it's unlikely. If I don't get an intake temp reading when this goes together, I'll track down on of the 13627547822 sensors. Here's the difference:

Converting from MAF to euro IAT to reduce intake restriction, or is there something else I'm not aware of?

[hubcapboy]

Real time update: Turner already designed a kit that breaks off the intake air temp sensor and uses a $15 sensor to be installed in the airbox... I can't think of a reason not to just install and connect to this sensor. *Particularly* since it can go anywhere, rather than in a special intake tube with a socket designed for the MAF!

[hubcapboy]

This ECU fan control pleases me. I expect that this is exactly what I'm going to be doing, with an additional override after the fan control box that puts my fan on high speed when my AC compressor clicks on. I won't have any feedback issues with an override switch... the thermostat will just behave as designed.

I'm currently extending and appending a Z4 wiring harness to suit the chassis (documentation to follow) and I want to confirm what we'd previously discussed related to the MAF/IAT sensor, because I have a pin number mismatch between the connectors on the X3 and Z4 harnesses I'm combining. Here's the BMW diagram for several of the N52 engines:





Pin 4 on the connector is always sensor ground (M_HFM) and Pin 5 on the connector is always the Intake Air Temperature Signal (A_TANS). These always connect to pins 27 and 28 respectively on DME Sub-connector X60005.

Pin 1 on the connector is always the MAF signal (A_HFM), but the DME pin for that signal changes between models. *I believe* this becomes moot, because Nando's tunes specifically do not use this sensor. Looking at the last diagram, "depending on version" some e90's after 2007 have a IAT sensor that doesn't include any MAF function or wiring. Which versions? Here's one example of a part number:

13627547822

Intake air temperature sensor

From:09/01/2005To:-Weight:0.016 kgPrice:Part 13627547822 was found on the following vehicles:

• 3' E90   (02/2004 — 08/2008)
• 3' E90 LCI   (07/2007 — 12/2011)
• 3' E91   (03/2004 — 04/2008)
• 3' E91 LCI   (05/2008 — 02/2012)
• 3' E92   (05/2005 — 02/2010)
• 3' E92 LCI   (09/2009 — 08/2012)
• 3' E93   (10/2005 — 02/2010)
• 3' E93 LCI   (09/2009 — 09/2013)
• 5' E60   (07/2004 — 02/2007)
• 5' E60 LCI   (11/2005 — 12/2009)
• 5' E61   (07/2004 — 02/2007)
• 5' E61 LCI   (11/2005 — 03/2010)
• 6' E63   (02/2004 — 07/2007)
• 6' E63 LCI   (05/2006 — 07/2010)
• 6' E64   (03/2004 — 07/2007)
• 6' E64 LCI   (05/2006 — 07/2010)

These are all European n52 models, but curiously not the European Z4... which kept the full sensor!

Rather than having these extra signals, grounds and power signals floating around in my harness, I'm going to pull everything but the two wires for the IAT out. Even if I left them connected, I have a 50/50 shot of knowing which pin we would send the MAF signal to based on the info above.

I don't know if power or additional grounding is required for the sensor I have to detect temperature, but I think it's unlikely. If I don't get an intake temp reading when this goes together, I'll track down on of the 13627547822 sensors. Here's the difference:

[hoveringuy]

So from my post above you've gathered that the thermostatic cooling fan and the MSV70 fight each other, and the MSV70 wins. It just says "fuck you" and reduces the coolant flow leaving the aux fan running, needlessly and loudly. I connected the VSS to get a valid road speed and also identified the wire for the fan activation. Not all PWM fan controllers will work, it needs to be one that works on a PWM negative signal. More ground=more blowing. Fortunately, the e46 has a nice little module built into the fan cassette.

Luckily, I had a bracket laying around that fit the module perfectly and mounts it on my stock fan frame that now has my Spal fan. BMW seems to want this prominently in the airstream so tucking it behind the headlights wasn't an option. I sourced the body side of the harness that the fan plugs into, and I could almost have literally just replaced the e30 plug with the e46 plug, it fits that well.

The e46 module gets wired to the battery and is controlled by the PWM signal. Since the stock aux fan has both a low speed and high speed power wires, I just combined those two together and used them for power. Those wires are connected to two relays that are controlled by the thermo switch, so I shorted the harness at the thermo switch so both relays energize with ignition.

In practice, it works perfectly.