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Link Fury x + DBW (multiple questions regarding wiring pro drift car project)

Practical Motorsport Wiring - Professional Level

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I am currently working on a new project and its my first time wiring this combo. I need to make sure of the wire sizes and I have some question to insure the best result before finalizing the harness.

I'd greatly appreciate your help with the below

- What wire size does the ECU need for its power supply and for wires going to the BMW e90 E-throttle body. I am using m22759/32 wires. I looked every where online for the amps draw and I can't be sure

- what wire size should I use for walbro 450 LPH fuel pump?

- is 20 AWG enough for each audi R8 ignition coils noting that the dwell time might be increased as the car is expected to run around two bars of boost or should I run two 20 AWG wires for each coil?

- Can I run one or two wires for all sensors grounds and 5v supplies to minimize the pins used on the bulkhead connector?

- is 22 awg enough for each injector (using ID 1300)

- what is the amp draw for AEM CD5 and Link CAN keypad

- Can I ground the ECU and ignition coils to the same point on the engine block and ground the dash, keypad, and fuel pumps to the chassis?

I am grateful for any input you might have to help me fulfill my dream of designing a fully sealed concentrically twisted harness for a pro drift car

What engine are you going to be using? and what chassis?

WOW, I thought you might be exaggerating, but there seems to be NO mention of current handling anywhere, other than mention of it needing 200mA to "operate" - I suspect that may be 'stand by', or 'sleep' draw.

Several of those components will have current, even current Vs voltage, data on their sites - you can size the wiring to suit those draws and the acceptable voltage drops to, or from, the controlled devices - not forgetting the other side of the circuit.

Regarding increasing the dwell time, unless the supplied dwell curves are very conservative, increasing the dwell, especially without properly scoping it, usually will not result in an increase in the output energy of the coils. Most factory dwell curves that I have seen are holding the dwell time at around 85%~90% of the coil saturation point, dwelling further beyond this point is only adding heat into the coil, sometimes with a corresponding drop in output.

The other issue that can occur with increasing the dwell times is that the coils will go into a protection mode and self discharge (preferable than popping, as older coils where prone to do when over dwelled) leading to inaccurate timing for the spark event.

I had many of the same questions the first time I fully wired a car too. Don't take my comments as gospel but I'll share what I've learned since I started doing PDM's and logging everything.

I am currently working on a new project and its my first time wiring this combo. I need to make sure of the wire sizes and I have some question to insure the best result before finalizing the harness.

I'd greatly appreciate your help with the below

- What wire size does the ECU need for its power supply and for wires going to the BMW e90 E-throttle body. I am using m22759/32 wires. I looked every where online for the amps draw and I can't be sure

Link has a separate pin on the B loom for DBW power, I don't think this has to be a separate power supply from the ECU but they do give you that option. Budget 4 amps for the DBW as a worst case, ECU is usually well under an amp. I typically put the ECU and injectors on the same circuit to ensure the ecu sees the same voltage that the injectors are for the dead times to be accurate.

- what wire size should I use for walbro 450 LPH fuel pump?

With /32 I just jump to 12 AWG for each pump and fan, its a small insurance to prevent voltage drop and allows head room to upgrade the unit later. I can't really answer what amp draw will be without knowing the part number and base fuel pressure you're expecting to run, but 20 amps is typically a safe bet. See the attached chart for a rough idea of what you're looking for but there's a few 450 part numbers and you'll need to find your exact pump's graph.

- is 20 AWG enough for each audi R8 ignition coils noting that the dwell time might be increased as the car is expected to run around two bars of boost or should I run two 20 AWG wires for each coil?

I regularly run 20 awg from a branch point to each ignition coil. If you're going to use a bulkhead connector with size 20 contacts then I usually run 3 20 awg wires through the bulkhead and crimp them together at the ignition breakout connector. For turbo bmw's or inline 6's with the coil packs in the valley I recommend a sub harness for the ignition coils as that section of harness usually gets the most heat damage of all of it.

- Can I run one or two wires for all sensors grounds and 5v supplies to minimize the pins used on the bulkhead connector?

there is a current limit for each 5V source (can't recall if the Fury has one or two separate 5V supplies) but typically one 22 awg wire is more then fine for an engines worth of sensors. You don't need to run one for each sensor.

- is 22 awg enough for each injector (using ID 1300)

While I typically use 20 awg for injectors and solenoids, knowing the typical amp draw I'm sure 22 awg will be fine. Depending on duty cycle an injector can draw less then 1 amp (12 ohm high impedance)

- what is the amp draw for AEM CD5 and Link CAN keypad

Link keypad is a Blink Marine, they draw like 500 mA or something operating but I find the boot up spikes a bit higher. CD5 I don't know, I'd imagine a small amount like 2 amps based on my experience with other digital dashes.

- Can I ground the ECU and ignition coils to the same point on the engine block and ground the dash, keypad, and fuel pumps to the chassis?

Yes. Observe star point grounding and other good practices, but totally fine and way more practical to ground those listed items to chassis.

I am grateful for any input you might have to help me fulfill my dream of designing a fully sealed concentrically twisted harness for a pro drift car

Attached Files
  • F90000262-Pump-Max-System-Pressure-87-PSI.pdf
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Thank you so much for your great input. It was very helpful.

to answer the first question the chassis is bmw E90 with a fully built 1000hp capable 2JZ for Professional Drift.

It belongs to a pro drifter who is testing my skills to see if he'd recommend me to other pro drifters

I did a full loom for a bmw e46 with a 2jz running emu black and a piggy back setup for an automatic ford expedition twin turbo charged running also EMU black

However, this is my first time doing a concentrically twisted fully sealed harness for a pro drifter and I want it to represent my best work with zero mistakes

I just have a few follow up questions. IF the ECU draws less than an amp, then why does HPA recommend 18 awg wire for ECU power supply? would 20 AWG be more than enough to wire the ECU? or do I need to go to 18 awg

regarding the audi red ignition coils, I am using a bulkhead connector that can accept 20 awg wires. noting that the distance from the fuse box to the coils will be around 2.5 meters, is it safe to run 20 awg wire for each coil?

It may be related to voltage drop* - Every ECU will have a minimum operating voltage, ACROSS IT, and when cranking the battery voltage can easily drop to 9-10V, or less, when cranking a cold engine, it doesn't require much of a voltage drop in the wiring to, AND from, the ECU for that minimum to be reached.

Using the heavier gauge wiring gives a little more 'head-room' if the battery is weak, and/or the engine is hard to crank.

*personally, I'd run the max' gauge, or even higher, for all "power"circuits, to minimise voltage drops, but that's just me.

I'm curious since most temp and pressure sensors are crimped to a single sensor ground pin on the ECU, Can I run a single 22 AWG sensor ground wire to the bulkhead connector for sensor ground to minimize the pins used on the connector? and then on the other side of the connector, let's say the plug side, crimp the sensors ground wires to the single sensor ground wire coming from the ECU? or would this affect the signal?

when in doubt go with the larger awg. 20 will be fine, 18 will be added insurance.

I think the last Link I bench tested drew maybe 0.3 amps on my power supply, no DBW mind you.

Yes you can run a single 5V and sensor ground to the bulkhead and splice in the boot on the engine side, I regularly do this to save pins.

Sorry I answered that but got carried away with the details.

My advice is to bench test as much as you can before sealing the harness up. You will make mistakes and catching them before they cannot be fixed is important. Be thorough with your planning, check I/O in the software and build a basemap when designing pinouts. Do a continuity test and be very methodical when constructing and testing.

Based on the kind of questions your asking I think you're on the right track. I had similar ones when I did my first few harnesses as well.

Thank you so much for your input and advice. It is much appreciated. Can't wait for the end result.

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