Project 635 - 300HP RWD 620

[DADZSUN]

If you find the "throttle hang" is annoying, which I did on my G35, I bought a cool little device
called SPRINT BOOSTER

https://www.sprintboostercanada.com/?ht ... gJ2QfD_BwE

It sure cured my problem with the G35 throttle, which I hated when down shifting. It just plugs in between the pedal and the wiring harness, super easy. I still double clutch, so it really bothered me how bad the hang was in the throttle.

Nice tip Keith! I've heard of these type of devices but never really dived into it yet. I like the valet option on this one and will research it further.

[DADZSUN]

Excellent! Did you also get F/R weights for bias?

No, I did not. It was just a large single weight scale used for their moving trucks. They apparently do a lot of this for personal vehicles purchased out of province. I'm not sure why the Ont gov feels a Rav 4 in BC would be any different than one in Ont...

As for brake bias, I'm just using the 'ol lockup on gravel and hear/feel where it's reacting first. Right now, despite NOT giving the front calipers additional push from the MC per Tilton's suggestion, I'm still getting front lockup with 50/50 pedal bias. This is all bound to change anyways when I experiment with brake pad compounds.

Regarding the curb weight, even though the end result was still fairly light, I was incorrectly hoping for it to be a bit lighter. After a bit more thought, this weight makes sense. The large battery and the extra large fuel capacity (vs OEM 620) could easily account for 50 or so LBS. The VQ (+150-200lbs w/tranny), the the sound deadening paint (+50-60lbs), larger wheels & tires, and the larger capacity Koyo rad easily add to the 300-400lbs gain over OEM.

[DADZSUN]

Last week's push was well worth the effort as I finally managed to get the truck registered, plated, and insured. That's the good news.

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The bad/frustrating news is the on-going issues that are just teasing me - and preventing me from actually driving the truck.

Brakes
First, the passenger rear bleed screw decided to snap. That little POS wouldn't come off no matter what. Given that calipers are under $100 each, I gave up and ordered a pair. Problem solved, right? Nope, the calipers shipped used the smaller 2005 11.5" Infiniti G35 rear rotor - I was running the 'upgrade' 12" 2005+ model. Since the front rotors are only 12" as well, it made the rear look a little too big, so I kept the 11.5" calipers and ordered new smaller rear rotors. FINALLY, everything was mounted and after several unsuccessful bleeding attempts (in-line hydro on the rear line), I ran my vacuum brake bleeder hard - and success! With this Tilton setup and stainless/hard lines, these brakes are like concrete - almost feels like the wheels are locked. I suspect the friction is a little too weak but I'll give this setup a solid go before making a decision.

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First wash with my two toys.

Alternator
That damn thing died again! I'm really baffled because I'm running a very typical stand-alone system. My mechanic is starting to wonder if the alternator is shorting itself out. So I ordered a new one - except the usually 99.5% reliable Amazon lost my order. So I missed a beautiful weekend to get out and hammer out a couple hundred kms on this toy. I was so desperate I even went to the local pick & pull and there was nothing worth taking. I re-ordered the alternator an it's on it's way (actual progress on the tracking now). For good measure I'm running the fans on stand-alone switch for now. I'm not sure if it's the fans (proper twin relays and fuses), but every time I activated them the alternator seems to die within a day or two.

Thailand 620 parts
So this didn't prevent me from driving the truck, but it's been a PITA for a couple of years now so I figured I'd add this to the rant. When I first researched the 620, part of the appeal was the availability of 'new' parts, typically located in Thailand. Turns out a lot of their stuff is garbage. Either it just doesn't fit (different 620 models overseas?), or the quality is so poor that just installing them they start to fail. I've had issues with window rubber, side marker lights, door handles, window roll-up handles, etc... Their business strategy is pretty clear to me now. Knowingly sell their crap, and if you catch on they refund if you don't give a review. With less poor reviews they're hoping the next Datsun builder won't bother complaining, or what's happened to me - ordered so far in advance that when you are ready to use the product 1-2 years later, it's too late to complain. That last bit has really been a huge lesson - trying to beat inflation by buying in advance (or on sale) can really bite you in the ass once you're ready to use it down the road. IMO, it's just now worth it.

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I've been setting up a bike mount for the 620 now and came across a really cool fork-mount setup.

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For those who don't know, bike fork/wheel skewers vary in diameter and width. It's a real PITA to have a universal setup w/o swapping adaptors etc. This Rocky Mounts Drop Top uses a rubber liner and adjustable clamp to cover 90% of the standards out there - and it has a lock too!

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The front wheel will be tied down with a velco strap off the inside tailgate - and my universal bike carrier is done. I like this setup so much I bought a second one!

[ostaylor]

Great progress Fritz - I have bought so much of my build parts well in advance of actually using them, I do worry about the same issues. I always err towards reputable, high quality - but that's not always possible.

[DADZSUN]

Finally got some videos up. Enjoy!

https://youtu.be/KrQoe4iC4Nk

https://youtu.be/oyZ9gUlKyCs

[ostaylor]

Sounds amazing! Thanks for sharing.

[DADZSUN]

I've had a good week with 635. I'm a little over 350km now and I'm getting a better and better feel for the truck's habits and where I need to focus on short-term.

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In the meantime, I'm getting more of my 'bucket list' activities done with the truck that have been always part of the main plan. One such activity was to take it out mountain biking. I love mountain biking but the 30min drive to/from is a bit boring so having this truck certainly spices up the trip.

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Those Rockymounts Drop Top work awesome! Super easy to mount/dismount. A couple of strategically placed heavy duty velcro straps tied down with rivet nuts do a great job holding the rear of the bike down and the front wheel.

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Finally, I decided to stop by the local Nissan dealership to see if they can use their Consult 2 to reprogram the throttle settings. I'm still getting high idle (1200 rpm) and it's a little sticky/hunting around.

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They were able to connect, but couldn't reset the ECU because the donor was an automatic and therefore Consult 2 wants the Park/Neutral switch 'on' before programming. Naturally I don't have that, so I'm a little stuck. I can always to the 'pedal dance' but without a Check Engine light to reference it will be a bit of a crap shoot.

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Also on the list to-do is the suspension. The alignment has yet to be done and I've like to get the springs done before then. I've reached out to BC Racing to see if how much softer I can go with the current damper valving. I seem to recall 3kg which seems like a big swing but I can always sort the springs first then re-valve if need be.

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I also finally found the replacement part number for G35x front lower control arm sway bar mounts. With these and the future softer spring rate I'm going to reinstall the front OEM bar.

Brakes are understandably poor due to unknown pads and non-assist. I've got some 'Powerstop Extreme' pads coming in (normally $100+ I got for $34 on old stock) to see f they have a better initial bite. As reference the R33 Skyline calipers use the same pads as Z32/300zx and 200sx.

Besides they there's a ton of fit & finish to slowly work through. Right now I'm working on sealing the windshield cowl, whenever water gets on/in there some leaks into the cab. I'm also hoping to finish the remote fan control today - my next posting will likely cover more of that in detail.

[iceman510]

Finally, I decided to stop by the local Nissan dealership to see if they can use their Consult 2 to reprogram the throttle settings. I'm still getting high idle (1200 rpm) and it's a little sticky/hunting around.

They were able to connect, but couldn't reset the ECU because the donor was an automatic and therefore Consult 2 wants the Park/Neutral switch 'on' before programming. Naturally I don't have that, so I'm a little stuck. I can always to the 'pedal dance' but without a Check Engine light to reference it will be a bit of a crap shoot.

Could you temporarily rig up a false switch ECU input to clear that hurdle?

[DADZSUN]

Could you temporarily rig up a false switch ECU input to clear that hurdle?

I was hoping I could but I can't find any reference to a park/neutral switch for the G35/350z automatic transmission. I'm wondering if it's an internal switch and sent to the ECU via CANBUS...

[DADZSUN]

A quick update on 635's final tweaks.

Suspension: I've installed the front sway bar and turn-in is definitely a little sharper w/o much extra stiffness. Regardless, I think I'm going to swap out the front 10kg springs to 8kg which is closer to the 350z Nismo suspension for a heavier vehicle. Once installed I'll get an alignment and be done with that.

Brakes: Rear matching pads are now installed and overall the system is adequate. It actually stops quite quickly but you need F1-like leg strength to get it. I can now lockup the rear quite easily with the hydro handbrake so I'm starting to play with that. Eventually I'll mount a remote vacuum-fed dual booster unit under the bed.

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Throttle hang: Based on Z-Fever's recommendation the Nissan drive by wire throttle relearn is moot due to the Osiris settings on my hacked ECU. He was convinced it was either a dying Throttle Body and/or the 3" ID DC Sports intake tube is throwing the MAF sensor off due to higher velocities.

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A brand-new Hitachi/OEM TB was installed and a new issue appeared, constant/aggressive self-revving (video https://youtu.be/onEcGGVN7E4). The throttle is snappier however so I think it's a worthwhile investment. My next course is to go to the pick & pull to source a cheap OEM airbox/intake with 2.5" MAF cross section. I really hope that's it because that the last major piece and I can wrap Phase 1 up with a fun review/write-up.

[bertvorgon]

Did you use the factory clutch line? That was another issue..NISSAN put a restrictor in that line,
thus making the clutch quite laggy...at least for me. Nissan Motorsport makes a NON restricted line.

I guess they did not want the briefcase set to dump the clutch.

[DADZSUN]

It's been a pretty busy few weeks and I've been really enjoying the pickup. Like, this type of a vehicle has been missing for WAY too long in my life, it really is good for my soul!

Since the last update I've installed 8kg front springs vs the original BC Racing coilover 'extreme low' 10kg. What a massive difference! Much more supple on the shit roads around here but still taunt and responsive. Damper adjustment can stiffen things up in a hurry if need be.

I've decided to order another muffler to plumb in the exhaust line. I love the sound but I'd rather enjoy that power w/o alerting the police or pissing off locals.

The high idle / throttle cycling continues to be a PITA. I brought the truck to the closest Uprev authorized tuner, ACSP Racing in Montreal to try and fix it. I ended up with a mixed bag of results.

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The owner tried to address the idle issue but Fever Racing setup the harness/ECU to lockout any form of adjustment/calibration. In the end, with all these attempts I had a truck that still idled high and/or cycled and/or just started in limps mode. So 5+ hrs of work and zero progress.

https://youtube.com/shorts/UvnAnaduJAQ?feature=share

Here's a video from the next day that shows how it cycles on it's own then settles into a high idle, and repeats once I press the throttle. Slow speed driving is also tricky, if the throttle is light enough it will engage drive (easily felt with torque, and heard with the single mass flywheel). It's almost like the cycling is continuous, but when I'm at larger throttle requests the cycling is suppressed.

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The good news is that he still managed a successful tune. He found close to 20 hp/ft as the truck was really running lean with the DC Sport short ram intake, Blox plenum spacer, pre-cats removed and main cats swapped to high flow. Not bad for a VQ with over 110,000 km. It sounded pretty damn good too - the video gives the actual volume no justice...


https://youtube.com/shorts/cYHuvOsN4x8?feature=share

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In the end we ended up with 228hp to the wheels on a Mustang dyno. That's not huge numbers obviously but the torque curve is super flat and I've read that Mustang dynos are quite conservative, most stock 350z recorded 190-210 whp. Regardless, I'm not chasing peak numbers but rather fun/reliable/linear/torque - and this delivers in spades within this chassis! On the drive home at 10:30 PM blasting through Montreal, I could certainly feel the tune - and their shitty roads!

So what's next? Fever Racing is still working with me to resolve the idle/cycling problem. They figure it's the ECU so it will get swapped along with the tune. If they don't manage to fix it I'll likely look at Link G4X instead - something I probably should have done all along, but that product was not available when this project started.

The truck has yet to get aligned, I'm hoping to do that this week in anticipation of an autocross event this Saturday. Despite being a 'truck', I've been granted permission to compete due to the car suspension, and the fact that it is wider than it is taller.

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I've also got a high speed vibration which I originally (incorrectly) suspected as misbalanced rear wheels. I'm now figuring it is the wheel bearings. I have not clue how old these units are, and based on the front crunchy units, they're due for replacement anyways. The cool thing is that 370Z wheel bearings are not only MUCH beefier, but cheaper and already pressed onto the hub. All I needed to make this upgrade work was new set of 370z rear axles to work with the hub's different spline (axles need to be swapped left/right when used on 350Z subframe). The parts are in my garage and will be mounted as soon as new axle bolts are sourced.

More summer plans/upgrades planed but I'll save that for a later post.

[DADZSUN]

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Shortly after my last post I wanted to take 635 to an autocross/Solo2 event. First, and alignment need to be done.

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Overall the truck was crabbing just a bit (no surprise). After the alignment the steering was straight and she tracked better. On-centre is still a little light, but overall it's a very easy pickup to steer (Toyota electric assist definitely helps!). With that done it was time to dodge some cones...

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Solo2 is a GREAT way to safely test the handling traits of a vehicle, and put a little more load into the build to see what breaks or comes loose.

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POSITIVES: This truck chassis dynamics are shockingly well behaved - easily the best trait of this build. The G35 modern suspension with poly bushings is paying off far more than I anticipated. Very predictable, nice balance, even the unassisted brakes hauled the truck down sufficiently. There was enough power and not enough tire that I only hit full throttle for maybe 1-2 seconds. Even the 6+ year old front used tires held well. I really was pleasantly surprised and relieved.

NEGATVES:

• That viscous LSD is either very tired, or she's really a full open diff. I don't really care because I'm still undecided on final drive ratio and a Quaife LSD will eventually be installed anyways.

• The other concern is that a knocking/metal rubbing sound emerged. It was loud enough that I pulled the plug at noon for the sake of safety and retain the ability to drive home. Since getting home I see ZERO signs of rubbing/looseness/flexing... very confused as to what it is. It seemed to be almost 2 noises, one from the front when braking and the other during moderate turning. Here's a youtube vid and you can clearly hear the noise, especially at the end: https://youtu.be/0LmTDswbZR4. I'm thinking it could be the new muffler I installed being too close to the driveshaft (no sign of contact), and the 370Z rear axles bottoming out on the 350Z rear subframe (I didn't bother installing the 350Z brake backplate/shim as it was less than 1mm).

• Finally, a slight tick/grabbing noise emerged from the steering - to be determined if it's the u-joint alignment, or something internal to the Toyota electric steering column.

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For civil street duties this truck is pretty much done and LOTS of fun... with the exception of the damn Z Fever hacked ECU and DBW system. What was supposed to be the easiest part of this built continues to nag. I'm getting more and more limp mode start-ups to the point I've stopped driving it in town where there are traffic lights.

I'm consistently getting error code P0183 (Fuel temp sensor A circuit high) and P1124 (Electronic throttle control (ETC) motor power). When the codes are cleared the truck still idles high (1400 RPM) but doesn't self cycle in revs. After a bit the auto-reving starts and the code is thrown. I've tried new throttle body (immedately cycles at start-up and at higher revs), and several DBW pedals.

Here's a vid, you can see I'm not touching the throttle and it's self cycles then settles (not all the time). If it settles, I only have to tap the throttle and the cycling returns. https://youtube.com/shorts/UvnAnaduJAQ?feature=share.

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Even more curious, ODB2 is showing that I'm only getting a max of 84% full throttle (during the dyno session too?). The vendor (Z Fever) has offered to test my ECU and if required port my Uprev tune onto my backup ECU at no charge. While I appreciate his effort to rectify this, if this last effort to fix doesn't work I'm going to ditch this system for a proper aftermarket ECU.

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I was originally looking at a Link G4X 350z plug & play setup. However, the Link does not work with the OEM widebands (front two 02 sensors), and because it's a PnP it looses the single onboard wideband controller too. This forces me to purchase dual external wideband controller and quickly loosing it's cost advantage.

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Haltech Platinum Pro is also a plug & play unit and DOES leverage the OEM 02 sensors. However, the tech is getting old and it's pretty pricey ~$3200 CAD w/taxes. Still, it's likely the simplest solution.

Both of the previous examples leverage the Z Fever hacked harness which may also be the issue. Not only is this harness hacked, but the connectors are getting old, and the spare 2-3 feet of loom is currently jammed between the firewall and block.

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For an extra $1300CAD (total $4400 w/tax) over the Platinum Pro, I can pickup the Haltech Nexus R3 VCU with universal loom. This crazy little box has the usual awesome ECU controls (DBW, on-board wideband, traction control, cruise control, data logging, accelerometer), AND it has a new engine loom. But the best part is that it includes an integrated Power Distribution Module. Essentially it's a solid state fuse box where virtually fused circuits can be created to run the fans (w/o relays or fuses) and other circuits. The features and future scalability alone make this a very tempting toy...

Either way, I should find out by mid-July if the hack OEM ECU was the issue, if not then I'll move on.

[bertvorgon]

For what it is worth, I find that the VLSD is crap in these cars. I HATE the lag for it to hook up, it never feels...until it does lock...that you can trust that both wheels will be putting power down.

It has been my biggest complaint in my G35. I have found, that I have had to change my driving style, of, on a "toss" in, I have to do it earlier than normal, so that in a sort of predicted way, power can be applied when I need the rear to hook up. We are talking a blink earlier.

Been spoiled by my Nissan comp LSD!!!

I also, even with that sprint booster device, a smooth throttle and return to a constant idle in a timely manner is just plain random. Drives me crazy. What the hell were Nissan engineers doing?

Many years ago I came to the conclusion that these motors are happiest on the Great Rolling Dyno, last years canyon carver proved that big time.

Watching your thread, amazing what you have accomplished!!!

[DADZSUN]

Been spoiled by my Nissan comp LSD!!!

I also, even with that sprint booster device, a smooth throttle and return to a constant idle in a timely manner is just plain random. Drives me crazy. What the hell were Nissan engineers doing?

The Nissan comp LSD is clutch no? I've always struggled a bit with clutch diffs. I find initial turn-in understeers as it fights the rear (compared to helical). For drifting, clutch setup is a no-brainer. Regardless, you're correct, this Nissan VLSD has always been crap.

I'm seriously considering a 2002 Q45 2.76 R200 along with a Quaife helical. 2.76 is a 20% jump over my current 3.55 but I HATE having to shift out of first at only 30kph (ie: middle of intersection) and 120kph in 6th is a little high at 2800RPM (my wheels are 1" shorter than 350z/G35). The hacked CD009 works but is too clunky to fire off rapid shifts to really enjoy shorter gearing (not to mention the ample torque makes it a moot point). A 2.76 would change my setup to effectively a 5 speed for the 2-lanes, and a 6th overdrive for 4 lanes.

Interesting on the DBW challenges. When I autocrossed my 350z I attributed much of my success to the ability to easily modulate the VQ35DE. Having read other threads, there are LOTS of people who felt the same as you. Regardless, the aftermarket ECU (20+ year newer tech) should speed things up a bit with the DBW system.