73 240Z VQ37VHR Swap Build Log

[Sanchez]

The wire harness from Hexa Garage should be arriving today, hopefully I’ll get the engine fired up in the next few weeks. I’ve moved on to the front chassis rails for repairs now and keep finding myself in the dilemma of: 

1) Get pre-made rails like the ones from Zeddfindings or KFVintageJDM (minimum $500 after shipping) with stock strength and will still require bracing the sway bar area, and frame rails (another ~$400 from same vendors)… or…

2) custom rails using 14ga 2.5” square tube and butt weld it to the inner fender and firewall, then tie it into custom full length frame rails made of 1”x3” box tube (cheap and strong) like was done in this thread https://www.zcar.com/threads/how-i-replaced-the-frame-on-a-budget.402729/

 

I like the idea of the custom hybrid-frame made from thicker steel for keeping everything strong upfront and the price is hard to beat, my only worry is the strength of a butt weld holding those rails to the inner fender and firewall.
 

Any thoughts or experiences? I’d like to hear how others on here have done it to decide what’s the safest route for a mostly street driven car?

Edited October 18, 2021 by Sanchez
Added clickable hyperlink

[Exposed]

@Sanchez I did something similar to my front end when I redid it, I ended up using 2x2 0.125 wall thickness. I havent driven the car yet but looks a lot better than it did. If I was to redo it again I would run the frame rails all the way under the floor pans and brace everything up together.

[Sanchez]

3 hours ago, Exposed said:

@Sanchez I did something similar to my front end when I redid it, I ended up using 2x2 0.125 wall thickness. I havent driven the car yet but looks a lot better than it did. If I was to redo it again I would run the frame rails all the way under the floor pans and brace everything up together.

I’m definitely going to tie it all together from front to rear. Any reason for choosing 2”x2” and 0.125” thick metal? That seems like it might get tricky to weld to 18ga steel, at least for a novice welder like myself. How did you notch it and add metal for the holes where the subframe bolts with 2”x2” I measured that the middle of the bolt holes actually go into the lip/seam where the rail and fender wall meet?

[Sanchez]

@Gumiho3

Over the holiday I went to fire up my engine with the HexaGarage harness and ran into an issue. I had everything wired up how they labeled it but seem to not be getting and pulse from the ECU to the fuel injectors. We got it to fire for a second by spraying starting fluid in the throttle body but the injectors just aren’t pulsing. I emailed Matt at Hexa and I’m waiting to hear but is there anything I may be over looking that you used to fire yours up? We were thinking maybe the clutch pedal switch to tell the car my foot is on the clutch or something?

[Gumiho3]

Do you have about 7 wires that are labeled? I out the vvel, fuel, 12v,ignition, starter on the positive side of batt and the rest on negative, as they should be labeled ground. I dont know if i threw any codes, but i didnt have my alternator hooked up so i wasnt able to rev up the engine.

[Gumiho3]

As soon as you attach the ignition wire to the batt you should hear the engine clicking and stuff. Did it do that?

[Sanchez]

@gumiho

Yes on + side I have the ignition wire to a switch, ECU battery connected, VVeL battery, and fuel pump relay positive, along with starter and and alternator leads attached. On - side I have the 4 labeled ground wires, fuel pump ground, and an engine to battery ground.

When I turn on the ignition switch I hear the throttle body motors whine (which a friends G37 does too so I assume thats normal) and when I tap the starter wire to battery + it cranks (OBD2 scanner shows cranking RPM at 160). Got a quick fire on starting fluid so there seems to be power at the coils but for some reason the injectors aren’t firing. We tested continuity form the ECU to the sub harness connector for and it was fine and supply a power and ground to injectors for a second opened them and we watched fuel pressure drop at my regulator when doing it so I’m leaning towards they didn’t modify the ECU correctly. I even cracked open the ECU to see if maybe it was damaged since I got it from a totaled vehicle and all of the resistors and connections inside look clean and undamaged.

I also had an unterminated connector on mine that I had to spend hours pouring through the horrible 370Z/G37 FSM just to find out what they were because I haven’t heard back from Hexa yet. I added a picture of what I believe they are and connected the Neutral Position switch to power and that had no change either.

 

I had an idea that it might be the Cam and Crank sensors since I have an Altima that had a similar crank but no start situation due to the Cam and Crank sensors, but there’s also some odd readings from my OBD2 that seem like things just aren’t right with how it was reprogrammed. I’m getting a code U1001 which is for ECM CANBUS communication error. The Wideband 02 are reading a constant 14.7afr when cranking even though no fuel is being supplied. I’m getting absolutely no other codes so unless they bypassed the cam and crank codes for some reason there’s no reason to suspect those are the problem.

So far HexaGarage has not replied to emails from a week ago but it is around the holidays so I’ll give them the benefit of the doubt.

Edited December 6, 2021 by Sanchez

[Gumiho3]

That does sound like an ecu problem, Hexa has been slow with service lately, i would definitely try calling Matt instead of email.

[Gumiho3]

(415)724-0675 this is his number. It's not anywhere else on the site for some reason. Hopefully it all gets sorted out.

[Sanchez]

Got the engine fired up! It took bribing a local Nissan/Tuning shop to bring over their CONSULT III machine to discover that the ECU was never getting a “Start” signal because there was no continuity from the Neutral Position Switch back to the ECM. A simple and easy issue to fix but one that is near impossible to diagnose without professional equipment or continuity testing 150 individual circuits.

 

the engine fires up in 1/4 second and sounds healthy and shoots some pretty nice flames out the headers so It looks like I’m done with half the wiring on the car which is a relief since I’ve nearly finished my body wiring diagram in some CAD software.

 

I did eventually hear back from Matt at HexaGarage so all-in-all I’d recommend them for a alternative to ZFever on the wiring. Though I know ZFever has a test engine to make sure everything is ready to go before sending out their harnesses. 

Edited December 14, 2021 by Sanchez

[rossman]

Congrats Sanchez!  Glad to hear you figured it out. What CAD software are you using for the schematic wiring? I recently downloaded KiCAD but haven't really used it yet.

[Sanchez]

@rossman

Thanks! It was a big relief to figure out the problem after spending 3 weeks pouring over hard to find diagrams and ECM logic charts to figure out it was just one simple broken wire. Would have never figured it out without a high end diagnostic machine that could read values my normal OBD2 app couldn’t. My friends who own the garage got a video of it firing up with some revs so I’ll post it up when they upload it to YouTube.

I’m using TinyCad because it’s free and has a lot of options. I can make my own switches which is nice but wire color options are lacking and the diagram size is small so I had to make supharnesses on separate worksheets in the program. I was planning on posting it soon to get some feedback and share the component files I made for everybody to use like the combo switch and ignition switch for a late model 1973 240Z.

Edited December 15, 2021 by Sanchez

[Gumiho3]

That's good to hear the harness is all good. What route will you go with the driveshaft? I was going to go with zfevers, but wanted to see if the stock 370z carbon composite driveshaft could be modified. Any thoughts?

[Sanchez]

@Gumiho3

I’ve been deliberating that along with my flywheel choice too. The ZFever seems solid and measured out very well for a swap but I think only comes with an R200 as the rear end, and I’m planning on a Ford 8.8 so I’ll probably need to go completely custom. I may just bite the bullet when the time comes and have a carbon composite shaft custom made, looking around it’s surprising how relatively cheap it is to have driveshafts made in steel, and aluminum and carbon are only a bit more expensive. I would not trust myself to modify a carbon shaft personally and it seems to me that aluminum usually comes out to a similar weight as carbon composite. In fact in the RX8 aftermarket community they make an aluminum driveshaft that weighs less or the same as the stock carbon.

[rossman]

Have you guys ever bought anything from Zfever before? My experience when buying an S30 aluminum fuel tank from them was less than stellar. Hopefully their service has improved but I would be wary of a shop who promises a 4 week lead time but actually delivers a defective product more than 4 months later after numerous excuses instead of being straight with me. I ended up paying them $800 for the tank then another $100 for a  local fab shop to relocate the fill pipe into the correct position.

[Sanchez]

12 hours ago, rossman said:

Have you guys ever bought anything from Zfever before? My experience when buying an S30 aluminum fuel tank from them was less than stellar. Hopefully their service has improved but I would be wary of a shop who promises a 4 week lead time but actually delivers a defective product more than 4 months later after numerous excuses instead of being straight with me. I ended up paying them $800 for the tank then another $100 for a  local fab shop to relocate the fill pipe into the correct position.

I have been to their shop 2-3 times while I lived in Tampa with my Z as my daily driver to check out the shop and for a multipoint inspection before taking my Z on a 1000 mile trip back home to the Midwest. I’ve heard some good things from other people in the area who have work done directly with them, but haven’t experienced dealing with them through online storefronts like eBay or general shipping. I will say Hexagarage’s product works, it’s 1/2 the price of Zfever, and I had my harness back in my hand within 3 weeks of them shipping it. Matt did say they continuity res their harnesses before sending them back, but in my case they definitely did not continuity check at least one wire and it caused me 2 weeks of headaches and $100 dollars to borrow a Consult 3 capable diagnostic tool. It seems I’m an outlier though since @Gumiho3 had no issues with his.

[Gumiho3]

Same here, zfever was pretty good on shipping me my shifter relocation bracket and motor/trans mounts. I was going to try and get a gas tank from them, but the price leans me towards a drop in solution.

 

Will you be running T3 8.8 rear end conversion? It looks like a solid setup. Whats next for the Z?

[rossman]

20 hours ago, Gumiho3 said:

Same here, zfever was pretty good on shipping me my shifter relocation bracket and motor/trans mounts. I was going to try and get a gas tank from them, but the price leans me towards a drop in solution.

 

Will you be running T3 8.8 rear end conversion? It looks like a solid setup. Whats next for the Z?

It's good to hear that you guys have had good experience with them.  I hate bashing vendors, everyone makes mistakes and maybe I was just the unlucky one.

 

Anyway, in the end, besides the problems I had with delivery and product quality, I feel there are better and cheaper options.  The tank suffers from the dreaded left turn air sucking lean condition - same as the stock fuel tank.  If I were to do it all again, I would go with one of the many drop-in solutions that are on the market today or delete the spare tire well (I don't carry one anyway) and install a fuel cell.

[Sanchez]

@Gumiho3

My suspension will be Apex Engineered all around, likely the 8.8 rear end but they recently made it available with a 370z R200 rear end which would be nice for having to buy less things (wouldn’t need to also buy Ford axles just for the CV and could just buy a 370z driveshaft and have it cut to size possibly). They are also hopefully releasing their VQ engine mount front crossmember soon.

As for fuel tank I like the look of ZFever but a universal in-tank pump like the aeromotive stealth or a “black box” seems like a better way to go and while installing it you can get in the tank and clean it out.

I think when dealing with handmade items and small business parts or service garages you end up with all these small issues like Zfever fuel tank needing work to fit right or in my case I opened up the wire loom from Hexa yesterday and found the neutral position switch signal wire didn’t have continuity because it was never actually hooked up to the wire it need to be hooked up to. Most of them are trying their best with no I’ll intentions for the consumer, they’re just trying to run a business while also usually be a part of the production, shipping, and customer service team all at once. Can’t fault them too much for some delays and small errors as long as they accept responsibility for them.

[acpmick]

Hi. Super cool build. I am hesitantly following in your footsteps. Lol. This wiring scares me and I am usually pretty good with wiring. I do have some questions for you in regards to the electrical. When I spoke to Zfever he mentioned that he can leave wiring for canbus gauges and fan switch. Do you know if thats an option with hexa , I tried talking with them but I was not able to get a meaningful conversation. What do you have planned for gauges and fan?