BMW Electrical Sensors, Switches, & Relays

Transform your N54-powered BMW with the Turner Motorsport B58 Ignition Coil Conversion Kit—the ultimate solution for ignition system reliability and performance. Designed to eliminate the notorious misfires and power loss caused by factory OE pencil-style ignition coils, this kit is a game-changer for stock and modified vehicles alike. Whether you're chasing more power or improved drivability, the B58 ignition coils deliver up to 2.3x more spark energy, unleashing the full potential of your engine.

Why upgrade? The answer is simple: B58 ignition coils outperform all other ignition upgrades on the market with unparalleled spark energy and reliability. Ideal for high-performance builds or daily drivers, this kit eliminates common ignition problems while supporting increased power demands from software tunes like MHD or BM3. Plus, with the included plug-and-play wiring harness and proprietary boots, installation is seamless—no cutting or splicing is required.

Features:

Up to 2.3x More Spark Energy: Maximizes overall performance, offering sufficient output for heavily modified engines.
Plug-and-Play Installation: Includes custom brackets, wiring harnesses, and boots designed for factory mounting locations—no modifications needed.
DME Compatibility: Compatible with factory engine management software for hassle-free integration.
Rugged Durability: Bolt-on brackets are precision-machined from 6061-T6 aluminum with a sleek black anodized finish for a premium look and long-lasting performance.
Proprietary Design: Boots feature a built-in 1k OHM resistor to prevent electrical contact failures commonly seen in other kits.
Kit Contents:

(6) Turner Motorsport B Series Ignition Coils for N554/N55
(6) Turner Motorsport B58 Ignition Coil Conversion Wiring Harnesses
(6) Turner Motorsport B58 Ignition Coil Conversion Brackets
Optional Kit Selections:

Spark Plugs:
Bosch ZGR6STE2 (OEM)
NGK 97968 (One Step Colder)
NGK 97506 (Two Steps Colder)
Spark Plug Socket:
Schwaben 14mm 12pt Magnetic Socket
Schwaben 14mm 12pt Swivel Socket
Turner Motorsport offers a comprehensive installation guide, including detailed removal instructions and high-resolution images.

All vehicles will lose some degree of performance due to heat soak under the right operating conditions.  Engine management systems constantly monitor operating conditions and modifying parameters based on sensor inputs. BMW integrated the intake air temp sensor in the MAF housing on models such as the E39 M5, and, being sandwiched behind a hot radiator and in some applications next to an even hotter valve cover, this is less than ideal for performance applications. Absorbing excess heat from its surroundings, the MAF can’t shed it fast enough, and the ECU reads an inaccurately high intake air temperature. Compensating for this false hot air measurement, the ECU pulls timing and runs a richer fuel mixture, resulting in a significant loss of torque.

What can you do?  Locate an intake air temp sensor in a location where it can properly measure incoming air temps and where it's less prone to heat soak. Mounting the sensor further away from the heat source and isolating it from the MAF housing, it can both resist the effects of heat soak longer and respond to temperature changes more quickly.  The result is you’ll experience reduced torque loss and more consistent power output when you’re pushing your engine hard. 

The Turner engineering team was initially skeptical of the claimed performance benefits of this modification. They first set out validate the functionality and performance benefit of a temp sensor relocation. Replicating stop-and-go traffic heat soak in a 2001 540i was a simple task in a controlled environment - their dynometer. First the car was heat soaked to simulate being stuck in traffic or moving at low speeds by running the car four times on the dyno with the dyno's cooling fans disabled. The fans were then turned on for three more runs to observe the recovery rate once air flow was reintroduced. The test: following this procedure once with a stock IAT, and once with their relocation kit in place. 

The result? Turner recovered 11lb-ft torque at 2500rpm through use of their relocation kit, with even greater recovery to be found for M5 owners. Here are the heat soak-related torque losses Turner experienced:

Stock IAT location:
18rwtq at 2500rpm
10rwtq at 3000rpm
9rwtq at 3700rpm

Turner IAT Relocation:
7rwtq at 2500rpm
5rwtq at 3000rpm
5rwtq at 3700rpm

**Click here for installation instructions**

The Turner engineering team designed a complete plug and play kit (unlike all other options on the market) that makes for quick, easy, and reversible installation. Weather-sealed connectors keep out the elements, while sheathed wiring offers a clean appearance underhood. With a harness nearly 3 feet long - the Turner IAT relocation kit offers flexibility in positioning, but not too long that you're left with unsightly excess wiring. Turner recommends positioning the sensor in a location away from engine heat, but still within the intake ducting to achieve accurate intake temp readings - such as the far side of the base of the airbox. Vehicles with cold air intakes with cone-style filters can even position the sensor in the end of the filter. Simply drill a hole in your (cool) location of choice and plug in the harness. More information including installation instructions and some good examples of sensor mounting locations can be found in our DIY PDF. 

We include everything you need to relocate your IAT, just select your desired sensor brand below - Genuine BMW or original equipment Beru.

Also the perfect plug-n-play option for anyone looking to upgrade their intake to utilize an Alpha-N tune!

Note for vehicles with M62 engine: applicable to 1999 and up

If you own an M57-equipped BMW, you already know this twin-turbo diesel powerplant is an absolute torque monster. What you might also know is that all that low-end grunt and high-compression diesel vibration wreaks absolute havoc on your accessory drive system.

From the factory, both the E90 335d and E70 X5 35d utilize a rigid alternator pulley. With each cylinder's fire, the crankshaft experiences a violent micro-acceleration. Because the alternator has a heavy internal rotor spinning at high speeds, it wants to keep spinning at a constant rate. When the engine suddenly slows down (even minutely between firing cycles), the alternator fights the belt. This constant tug-of-war results in extreme stress on your engine's belt-driven components. At best, it’s an annoying, unrefined chirp at idle; at worst, it’s a ticking time bomb for your expensive harmonic balancer.

To solve this issue, many enthusiasts choose to run a clutched alternator pulley (also called an overrunning alternator pulley). A clutched pulley allows the alternator to "freewheel" or coast when the engine slows down, completely isolating its rotational inertia from the belt drive to prevent component wear. While the N52's clutched pulley (12317560483) is a straight bolt-on, the offset is incorrect for the E70 X5 35d's accessory drive. Thankfully, our engineers designed this zinc-coated spacer to provide the precise amount of spacing needed to perfectly align the new pulley with existing belt drive components.