N62 Z3 Part 6: More Wiring & Fuel

This update covers a few days worth of work over about a week - the first day was spent digging through wiring diagrams to ensure all my wire gauge was appropriate. In doing so I also figured out what that "mystery" red wire was on the IVM - the one I have set on a separate circuit. I realized one of the harnesses isn't labelled on the pinout and when you go to show where that harness is, it shows you a picture of the IVM with an arrow pointing at the harness! It requires 60a on the E53 but 50a on some other models so I will likely start with a 50a and upgrade if needed.


I also ordered a lot of stuff... a bunch of wire to finish everything up once the pins arrive... 22, through 8 awg. As well as heatshrink, loom tape, battery cable end terminals, all the pins I need and some of the harnesses I need. Some other stuff I am sure I am forgetting as well. Ended up having to order from 5 different suppliers just to find stock of all the stuff I needed... all the electrical connector salesmen I talked to were super friendly though, so at least it wasn't too annoying to deal with


However, one of the harnesses I needed is NLA from BMW and the AMP part number is "restricted access" meaning I need permission from the manufacturer to order them. So that kind of reached a dead-end but I only need one pin off that harness so I will likely end up moving the pin I need into another harness with an empty slot

Then another run to a different junkyard looking for the other connectors I wanted. I didn't find anything at all there so went to the other local yard and grabbed the CPS off the 745i I had previously scavenged the crankshaft sensor off of. Helped my sister on her new Z3 a bit in the afternoon but took the time to swap on the CPS before I went home for the day

Now the engine harness is fully plugged in except the alternator. The wiring is almost done, although I do also need to run the main power cable between starter, alternator and main positive supply. I will find how that is routed and see how I can emulate that for the Z3


I also need a power supply cable to the fuse box (the stock Z3 engine harness runs a power supply cable across the engine compartment). I have an idea to integrate this all really neatly but need to verify the routing first. I am starting to think I should just buy a cheap Z3 engine harness...


In any case the wiring isn't too far from being wrapped up, so I am going to focus next on the fuel system stuff. I haven't even checked my M54 parts car fuel lines yet but I do have a hunch they are destroyed from being dragged up my trailer. I will take a close look soon to see if they are usable but if not I may be bending a second fuel line. And I know it doesn't matter but I think I found the routing for the fuel pressure regulator vacuum line - it seems to go through the electrical box

I also need to figure the cooling system routing out - but that isn't urgent. Although upon initial inspection it seems pretty close to the Z3 M54 setup. The N62 has one outlet at the back to the heater core, just like the M54 - this goes to the heater core inlet


The way the Z3 is routed is the heater core has an outlet to the heater core valve and then the valve returns to the expansion tank. The expansion tank has a return to the engine. This seems to possibly be how the N62 is routed, as I see a second coolant inlet port on the water pump - however it is capped on this engine. I know on the M54 the return from the expansion tank basically feeds directly to the water pump (specifically - it feeds into a plastic coolant pipe, which feeds into the water pump), so it would seem logical for the equivalent of this line to route to the water pump directly on the N62

I went camping over the weekend and when I came back I had a bunch of stuff at the door...

Not everything I ordered sadly, still waiting on a few pieces to finish the wiring... but a good chunk of it arrived. It's nice to have some extra pins just for good measure

I then decided to clean my workbench. Not really swap related except that everything on the bench was basically swap stuff

Anyways. I then spent the day working on the fuel system stuff

Below is what I was starting with

The M52TU system uses a fuel pressure regulator mounted after the filter and two lines going to the engine - a supply and a return. The N62 uses a fuel supply like the M54, with a fuel regulator integrated into the filter and a return line coming out the back of the filter, with a single line to the engine

So the first step was to remove the M52TU stuff - I removed all the stuff I didn't need and kept it intact as there was really no reason not to. The fuel filter, regulator, engine supply/return lines and main return line were removed

Then I inspected the M54 Z3 parts car... got a little lucky I think, but none of the lines were damaged! The fuel filter got a little damaged - the piece that holds it on must have gotten caught, as it was mangled and it bent into the filter. But it will work for mockup purposes

With that removed, acomparison of the M54 and M52TU fuel filter/supply systems. The M54 system is pictured without the single engine supply line or the supply line into the filter

I also got a better condition charcoal canister bracket off the parts car

And installed, minus the engine supply line

I used some extra fuel line to bend a supply line as well but it wasn't quite long enough to go where I wanted it to. I will end up routing the final line in a different way anyways - along the firewall instead of following the brake lines

Last things to do for the fuel system before it's done:

- Upgrade fuel pump

- Custom bend engine fuel supply line

- New fuel filter

And that should be it for fuel!

Still a long way to go but getting closer to attempting a first start. I have also heard from the person working on my gauge cluster that it looks like it is possible to adjust the tach for the V8 signal (so it reads correct RPM). My tuner also seems optimistic about things - the DME has been able to be set to "manual transmission" setting and is reading the VIN number of my car. It also looks like it should be able to be aligned to my stock EWS module, so it will all be integrated like OE, at least it is looking like it should be possible (knock on wood!)


Next I wanted to play with my new toys so I finalized the routing of this harness and started running some wires, replaced as many spliced wires as I could and wrapped it all neatly in loom tape, being very mindful of where each plug needs to terminate

Continuing on...

And this is essentially what the adapter harness ended up looking like. This is not all of it, but definitely "most" of it

And then I went ahead and mounted the IVM on the outside after trimming it down

The stock battery cable to the positive terminal will remain in place. The red cable coming off the IVM in the above picture will bolt onto the back of that positive cable. The IVM has an outlet 90 degrees to the right of where the current red cable is feeding into. I will feed the engine power cable out of this outlet. The fusebox will be powered the same way as factory with a cable running from positive terminal to the fusebox


I've also hacked up the parts car DME box pretty good by now (more cutting was done after the picture was taken), but I think I have everything about where I want it. I am going to install it for the test start and ensure it all works before trimming the spare intact DME box I have. I've had to move a few things around after cutting so it will be nice to start with a clean DME box now that I know where everything should go. I also trimmed the distribution block down to only the fuses I need and installed a rivnut (love those things) in the DME box to allow me to mount it. Worked perfectly. I had a little trick planned but forgot to try to use it - basically wrap the rivnut in the cut off finger of a glove, then when it is riv-nutted in place it should also be weatherproof. I will try this for the final iteration. I am trying to be careful to avoid water ingress, especially since I have cables passing from inside to outside of DME box. DME box won't be weathertight anyways due to the extra fan, but I want to make it safe to be driven through inclement weather. As the "exposed" fan is an exhaust I am hoping it won't be too much of an issue. The main concern is where the wires pass through the DME box - so I will either have a grommet or have RTV/silicone applied around them at these points


Oh my de-pinning tools I bought also don't work for the round pins I need to de-pin. Sooo I bought my first ever Genuine BMW tool! $60 for a freaking depinning tool but hey, sometimes you gotta pay to play...

The wiring is very close to being done at this point, kind of weird to realize that though. It's felt until now like every time I crossed one hurdle with the wiring it only revealed more, bigger hurdles. But now I think it's all finally figured out, heck the "adapter harness" is finished - just needs a few ring terminals. I was even able to fit the DME, Valvetronic DME and IVM in the DME box like I wanted to. It's pretty tight - I don't think that extra fan is optional - but it fits...


Oh on that note, I also drew out my own wiring diagram from scratch, to show the routing of all the wires on the harness I made yesterday, as well as the DME and IVM harnesses I've modified. So if I need to trace anything in the future, I can easily do so. I will even probably spend some time today learning how to plot it out neatly on Adobe Illustrator, so I can do things like change the color of individual wires and have a clean electronic version of it to save with my other notes. No pictures, there are some things I have to keep secret... that diagram took countless hours of research and figuring out to be able to put together. Not that I expect many to be eager to follow suit given the need to notch my framerail...


Once the fuel supply line is finished then the only thing left for me to do before a test start is finish the wiring! And "finishing the wiring" really only means swapping 2-3 pins into different harnesses and finalizing the battery cable routing. Just waiting on my depinning tool from FCP and terminals I ordered to be able to do that... So I am very close to a potential test start. I've decided I am not going to mount the engine for a test start except to bolt the transmission in. I've seen quite a few videos now of engines being tested just sitting on the ground and they jump around a little but then calm down a bit at idle. So I will just bolt it in at the trans and give it a test when the time comes. For now just going to keep putting one foot in front of the other!

Part 7!

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