you say it, and someone is selling just that on yja. https://page.auctions.yahoo.co.jp/jp...on/g1122310748
ad says it lets you drop this in your Z32, put their airflow data into the Power FC, and be done

 

I've actually seen that one before. Pretty neat. I've been considering switching to the R35 sensor and designing a custom housing for it to really keep the airflow as optimal as possible, but the Z32 one is currently working great and I don't want to mess with success.

I had to work out some 3D printer challenges, so I'm hoping to have some updates on the CAS bracket soonish.

 

It's soonish, and I have an update, albeit sort of a frustrating one. I was able to weld up the gear from PCBWay with no issues:









There was no drama. I clamped it firmly and welded in a few places, and the warped trigger wheel straightened out reasonably well. It could be a bit straighter but I don't think it'll be an issue in real life. Unlike VR sensors, hall sensors are quite forgiving.

I also sorted out some 3D printer maintenance and was able to print this bracket. It's in PETG (PC is stiffer but is finicky to print, so PETG is what I'm using for all the prototypes). If I grasp it firmly at the sensor end and push I can still flex it, but I think in application the amount of flex will actually be very minimal. Especially since there's no force on it front to back in real life.

I bolted it up (well, zip-tied) on the Turbo II engine to test, and everything looks pretty good:





Clearance to the trigger wheel looks good.



All the pulleys still clear.



Another view of the PS idler pulley still clearing the bracket even at it's lowest adjustment.



Clears the water pump pulley snout.



Clears the water pump pulley face.

So overall everything has gone really well. Except for the minor snag that it doesn't fit my S4 engine currently in the car, so I can't actually test it. It turns out the S4 water pump snout is different and so is it's pulley. The bolt holes line up but the centering bore is different. The actual snout is also in a different place relative to the water pump housing, so it's a bit closer to the crank and my pulley won't bolt up.

In my defense, the water pumps look nearly identical. I think it's only a few millimeters difference. But it is enough that I can't actually test. So for now I'm driving around with a prototype (using my old trigger wheel), but I can't actually test the new design until I swap engines.

I should have another update in a few days which you guys might find interesting. Until next time

 

Alright folks, it's storytime.

Today I hopped in my Rx7 after work for a brief trip to the nearest Purolator drop-off. I drove all the way there without incident, until the moment when I was about to enter the parking lot. Suddenly the tach went a little crazy and then the car just died with a weird clatter noise. It was still rolling (sort of) so I jumped out and pushed it the rest of the way into the lot and parked it. I managed to run over my own foot while doing so (but the Rx7 is light so it turns out that's no big deal).

I had expected a number of things. Maybe my bracket had come loose, or deformed from the heat. It was none of what I expected:





Remember the crusty old air pump belt that I was using? The one that I found on my shelf and came with the car 8 years ago? The one probably older than me?

Well, I let that temporary belt become permanent and I got what I deserved. The belt snapped, took out the alternator belt with it, and then snapped my bracket nearly clear in two. Here's a picture of it once it was removed:



Now as luck would have it, there was another bracket hot off the 3D printer and my dad was kind enough to bring it to me. I also grabbed a mostly correct alternator belt from the Canadian Tire, and the kind people of Staples (where I used to work) let me use their tools to remove all the support structure from the bracket.



The 3D printer really mangled the edge of that gusset, but that's a problem for another day. Met some nice strangers in the parking lot and we talked cars for a bit before I set off. I was able to get home without incident and the car will be laid up for a couple of days while I order the correct belts, and probably go back to my old sensor in the air pump location temporarily so I can drive the car without fear of this happening again (unlikely though it may be).

I learned something important. I definitely want to get the final bracket either printed in aluminum or CNC'd. A snapped belt is irritating, but if I hadn't had a bracket on the printer and my dad available to drive it over I would have been 100% stuck in that parking lot.

Overall though, I'm home and the car is fine. Plus I learned something and got to fix a problem on the fly. Not a bad way to end the day.

 

I'm glad to hear the car didn't suffer any major damage. Definitely get that 3d printed bracket made out of metal. If you can't find an affordable place locally, you could always use Send, Cut, Send, online. If you send your file in, they make it and ship the part back to you.

 

when you get to that point of getting it machined let me know. Looks like a fun part to make.

 

I had time to take care of a couple of small interior things that have been irking me, so I took some pictures along the way.

First off, my cigarette lighter socket stopped working awhile back. Confusingly enough I could actually see 12V on the multimeter when probing it, but then my USB adapter wouldn't light up. I decided the only thing to do was to take it apart and see what was going on:



So, this is kind of weird. If you look at the center piece in this image, that's the part that connects to the harness connector that provides 12V. Then the contact that sits inside the socket conducts through that center screw.

If you look carefully at the center piece you'll see that it's actually two pieces with a washer between them, and for some reason this washer is a non-conductive material. Then there's a small jumper wire that actually conducts the electricity.

This is kind of a weird choice. It's like one engineer decided to use a non-conductive washer and another one decided to use a jumper wire, and they never spoke to one another. I thought the small wire might act like a fuse, but this circuit is already fused so why put it there? I ended up replacing the little wire and that fixed the connection.

While I was at it, I also noticed an issue with the little light channel that throws light at the ring around the socket:



It's crooked. Probably because it's held on with JB Weld and I got it a bit crooked last time, but this is unacceptable. The socket lights up perfectly but the little outlet for the ashtray is misaligned. This means the light in the ashtray is dim.

Entirely unacceptable. How am I supposed to observe my ash collection in the dark?



With the new wire (and a lot more JB Weld) I had the socket issue fixed. Now I just need to start smoking...

I also wanted to take care of one place on my car where the interior dye didn't really hold up. This is the glove compartment lever:



It looked great when I first did it, but it's a high-traffic part and it's showing wear. Plus the bubbles indicate poor surface prep. Plus I was able to scrape a lot of that paint away with my nail.

I stripped it all back and sanded with 1000 grit sandpaper to break the shine, then degreased it thoroughly:



And hit it with SEM Color Coat:



The SEM is definitely better than the Duplicolor. I originally picked the Duplicolor purely because I like the satin finish better, but I'm a low-maintenance kind of guy, so if/when I have the occasion to take the interior out I'll strip it and recoat with the SEM piece-by-piece. That's assuming it stands up to regular use of course, since the glovebox lever will always be a high-traffic surface.

Next up is a choice that people might find a bit odd, but I installed a CD changer. I've had the matching Nakamichi MB-9 changer for my head unit for several years, and I actually wired the car up for it before deciding not to install it. Between the Minidisc deck (I have plenty of blank Minidiscs and a deck in my room to write to them) and the auxiliary input I thought that would be enough, but it isn't.

A Minidisc holds about the same runtime as a CD, which means every 80 minutes (assuming you don't skip any songs and don't feel like listening to something else). That's actually not a very long time. The same problem occurs with the auxiliary port because it tempts me to pick up my phone and change the song. Aside from being distracting, that's a serious offense here in Ontario and results in points on your license. My stereo obviously has no provisions for a Bluetooth connection nor do I actually want one. The last place I want to be easily reachable by cell is when driving my Rx7.

Also I like the spontaneity of the CD drive. Pretty frequently I like stopping by a garage sale and buying random CDs. For $10 you can get 10 albums and listen to something new. It's not like I find many Minidiscs at garage sales.

So whether or not it makes any objective sense in 2024 I decided to plug in the MB-7 and put it behind the seat:



The weird scratches on the front are from several years ago. I gambled on an "untested" unit on eBay for cheap (FYI "untested" on eBay means "I tested it and it's broken so I'll just sell it as untested") and it works, but something in the mechanism that lifts the tray doesn't work. So my solution at the time was to notch the front of the case under that door to allow it to just pop the tray out anyways. It's pretty ugly under there, but my work is (mostly) hidden when the door is on. That's not the solution I would choose if I were doing it today, but I must have felt differently when I was 18.

This unit is pretty neat though. The head unit can control it seamlessly without the need of an external remote, and it has both analog outputs and a coax digital. I'm sure the analog would be good, but my head unit accepts a coax in so I went with that. I figure that Nakamichi probably put it there with the idea that the DAC in the head unit is superior anyways.

The other benefit is that the Minidiscs rattle around in the door pocket. You can fit more of them, but it's also tough to see which is which:



Whereas CDs fit perfectly, and unlike my home dubbed Minidiscs they all have album art:



The Minidiscs now rattle around my center console instead of rattling around the door. I'll probably whip-up a little custom storage tray for them that fits inside the console.

When I have time one day maybe I'll decode the Nakamichi changer control protocol and build a Bluetooth interface to let me use the controls on the head-unit to control my phone. I'll also need to make sure this solution doesn't play call audio (ideally it won't even interrupt the song), but then realistically I barely have time as it is so this project is a long way away.

But until then I can listen to CDs:



While smoking a cigarette:



And quietly observing my ash collection:



Until next time

 

i feel like the lighter has that little wire as like a fuse. its kind of neat you can rebuild that thing

 

You have some really great posts on this thread. This latest was also very good.

I find it interesting someone else has a mini disc player for the car. The only decent head unit I have now is an Excelon from 20+ years ago. Mini disc player with a 5 channels of preamps and crossovers. Plus a four channel amplifier. This will go in my s4 when finished. This has the ability to use a disc changer remotely. Maybe I can hardwire an aux port and a Bluetooth dongle instead of the multi CD changer?

If you look long enough you might be able to find the travel cases so you won't need to hear the rattle if you ever return to mini discs. I have four full cases and some loose ones.
I only ever had 3 discs that weren't burned at home. Two Pearl Jam and a Pink Floyd. The Floyd one is about a $100 disc now. I lost one PJ one and have another one left worth about $50. Keep those discs in good shape, there is some money is some of those.

 

I actually like Minidiscs better than CDs, it's just that CDs are more common. Minidiscs don't get scratches since they have their own caddy. They don't skip when going over bumps. They're physically smaller while storing the same amount of music. And while I've heard plenty of talk about how they're compressed while CDs aren't I've never been able to hear any difference on decent hardware.

I grabbed this Nakamichi unit a few years ago since the price was right and I was trying to maximize audio quality while remaining period-correct. Aside from the excellent audio quality it's got a ton of I/O. Front and rear line-level outs, dedicated sub line-level outs, two AUX in (one digital one analog), two CDC in (one digital one analog, and I think they also work as AUX inputs if you don't connect the changer control cable). I remember reading about people making an adapter to use the changer cable as an AUX input (for head units that didn't already have one) but in my case the Nakamichi is already equipped. The problem I have with using the AUX port is just that I can't use the head unit controls to skip forward / back, and that leaves me tempted to pick up the phone itself.

The only thing I don't like is that the equalizer is very basic (low, mid, high adjustment only) but it was probably intended to be used with an external equalizer anyways. I'd like a DSP since I want to tune up the vocals a bit, but the speakers sound nice as it is so I have other things I'd rather spend on.

I'll keep an eye out for some cases but I've been thinking of designing a custom insert for the center console anyways. I was using a cupholder insert there for awhile but it interferes with my elbow so I moved to a cupholder in the little panel for the power mirror controls instead. Now the center console is just wasted space, and in Rx7s space is always at a premium

 

If that little wire is in fact a fuse, then I should probably remove the wire I installed and replace it with one of the same gauge as the original. I think it's weird for them to make a little fuse wire though. If it burned out on someone during the car's warranty period would they just replace the entire cigarette socket?

On the other hand the "cigar" fuse in the fusebox is 10A, so maybe there are other things on that circuit. I haven't looked into it but running 10A through those little wires would make me nervous.

It is neat that it's rebuildable. The entire assembly is held together by one nut.

 

yep! the early Mazda3's used a Bosch one, so it failed all the time, we were changing a couple a week

 

I've had a brand new OEM defroster vent sitting in a box for a few months, and for some reason I decided that now (after the weather has warmed up enough that I rarely need the defroster) was the time to install it. My old one had a crack straight across it's single mounting screw which I had unsuccessfully attempted to repair awhile back. Here's a picture of the new part:



Interestingly this part might actually be new:



I ordered in April, so that definitely isn't the date I ordered it. Unless maybe it's a batch number of some sort.

Here's a close up I took (at night, of course) of the broken vent:



And a nicer photo this morning that illustrates the problem:



As you can see, the broken fastener lets the vent fall backward of where it should and also sit a little bit lower. This means the hot air shoots up into the bottom of the dash garnish instead of out onto the windshield, hampering it's effectiveness. A repair might have been possible but when a new part is $25 it's hard to argue.

I also found this bolt was loose:



It was probably tight when I installed it, but the dash itself is cracked in that area so if it slides away from the windshield just a bit then tension on the bolt is gone and it loosens. I'd been hearing an occasional rattle deep in the dash someplace, and this is probably the culprit. On reassembly I used a big fender washer to try and grip what remains of the dashboard more firmly. Time will tell whether that works or not.

With all the dust and grime cleaned up and the new vent installed, you can see it sits quite a bit further forward:



For anyone interested, you absolutely CAN install this part without tearing apart the dash any further than I have photographed so far. You merely need to remove the single screw, unhook the inner fastener from the firewall structure, loosen the round inlet tube on the bottom, and then pull the vent up against the windshield and sort of rotate it towards you. You need to flex the vent a little bit but it won't break.

Unfortunately for me, when I was trying to remove the original vent I got it wedged in a weird position and convinced myself I needed the dash to come back a bit so I would gain more clearance. So I removed all of the dash fasteners and dropped my steering column to try and get myself the clearance I thought I needed:



... anyways, all I cost myself was about an hour's time. Plus I got to clean out some of the vents while I was in there. Remind me to design some sort of solution to install a cabin air filter.

Before I reinstalled the vent garnish I put some fresh foam on it to prevent rattling:



Once it's back in we can see just how much better the vent is aligned:



With the broken vent it was mostly under the garnish. I think this will greatly improve the effectiveness of my defroster, which I've always felt was a bit lacking. I'm also thinking a new blower motor would help, and so would resealing all of the vents under the dash with fresh foam.

Lastly I took care of a small problem that's been bothering me. With my relocated coolant reservoir, I would routinely lose a bit of coolant to evaporation. This didn't bother me a ton (it happened with the original reservoir too) but what did bother me was that liquid coolant would drip on the floor. In addition to a whiff of coolant smell every so often, and the green stains, I would always wonder "Is that dripping just the reservoir or have I actually sprung a leak this time?". Plus it's not good for the environment. While I wouldn't call myself an environmentalist or anything, I think it's a good idea to avoid wantonly damaging the environment whenever possible.

I figured the issue was that the original location (way over on the driver's fender near the shock tower) gave the coolant more time to cool down before reaching the reservoir. This made it less likely for it to evaporate.

The location where I installed my new reservoir is at the back of the engine bay near the highest point and also on the exhaust side. I had tried using a rubber cap with a small hole in it on the vent nipple for the reservoir, and also no cap at all, and either way the steam would escape and condense back into a liquid before dripping down. Turns out the solution was quite simple:



All I did was add this upturned hose. The hose adds a bunch of surface area on which the steam can condense, and then it drips back down into the reservoir rather than out onto the ground. Multiple drives later I have never felt any moisture at the exit of the hose. I'm sure I'll still lose coolant to evaporation, but at least it's minimized.

Also, my CD changer has already stopped working. It still responds to commands but no audio come out. I'm going to try diagnosing when I have time, but such is the life with 30 year old electronics.

Until next time

 

For awhile I've been planning on a fuel system upgrade. I'm obviously not maxing out my stock NA 460CC x4 fuel system or anything, but newer injectors have a number of benefits including:

- Higher flow
- Improved spray pattern
- Known injector characteristics (dead-time, small pulsewidths correction, etc)

To be clear, my goal with this is to eliminate some of the guesswork from my current tune (particularly injector dead time) and hopefully gain some fuel economy and idle quality. Larger injectors don't make more power, and generally larger injectors are harder to control at low pulse-widths which makes idle worse. But modern injectors also benefit from some significant gains in atomization, and since most of my injector characteristics for the stock units are educated guesses I am hoping that the gains will outweigh the losses.

Injector Dynamics was the obvious choice, and everyone says their products are second to none. The only problem is that their smallest injector, the ID725, is discontinued. I really didn't want to step up to the 1050 as that would be a lot more fuel than I need (even once the Turbo II engine is swapped).

So imagine how pleased I was to pick up an open-box new set from eBay for a very reasonable price. Here they are next to a stock Bosch injector:



The only problem is that they won't fit.

Obviously they're shorter than stock. This is intentional, and they are supposed to be run with the correct size of adapter hat for the application. But what I mean is that the top of the injector is actually shaped differently. Here's a stock picture I found:



See? The plastic near the top continues higher, and there is a small edge for the clip on the hats to engage with.

Turns out the reason the injectors I purchased were so cheap was that they were machined for a specific application. They were listed for Yamaha SHO, which I think is an outboard boat motor? I contacted Injector Dynamics and they were very helpful, but basically told me that there was no adapter to do what I was looking for and that the best solution is to just replace the injectors.

I did find some solutions that might work (I bought some 10mm to 14mm spacers from Aeroflow, and then the standard 14mm to 10mm top hats may have worked) but I wanted a solution that was secure. Also, some of the cheaper adapters don't include the strainer for the fuel, which I find sloppy.

We live in a time where we can make anything we want, so I spent some time designing this:



This adapter has the correctly sized inlet for my ID725s and outlet for the fuel rail, as well as a 6mm receptacle for the strainer and a small lip to prevent it falling into the injector.

I had a set printed in aluminum from PCBWay (only $34 for 5 units, and I already had store credit), and then tapped the strainer into place:





I also purchased a set of 4 Denso rebuild kits, so I had some fresh o-rings and donuts for the bottoms of the injectors. Here's how it all goes together:



The two o-rings on the injector are just for safety. I'm sure one would be fine, but o-rings are cheap. I also tested with those o-rings by soaking them in gasoline for a day. They're supposed to be Viton but you can't be too careful.

Here's a comparison:



And all four assembled:



The stock injectors use the rectangular Bosch EV1 connector, meanwhile the IDs use USCAR. I didn't want to cut my stock harness so I purchased these convenient little adapters:



To be continued

 

The next step was to actually install the injectors. I won't show the disassembly of the intake manifolds for access, since I've covered it before. One thing I will say is that eliminating the coolant running through the intake manifold makes the removal process much easier. I think it was maybe 10 minutes to have the upper / middle manifolds removed?

Here are the injectors I pulled out:







A few weeks ago I got in the car and turned on the wipers, and noticed that the wiper blades had lost their flexibility and weren't wiping very well. I thought "come on, I replaced these when I got the car!".

Then I remembered that I "just" bought the car 8 years ago. Time flies.

I had a similar experience with these injectors. Most of the ugliness is cosmetic (you'll notice the upper o-ring and the donut are in good shape still). I had these cleaned and flow-tested after I purchased the car and to my knowledge they are perfectly fine. But they are also probably one of the few original parts on the car which means they have 397,000 km on them. Does anyone know if injectors wear out?

Anyhow, I installed the ID725s. The install went without any drama, and the only thing I had to do differently was rotate the rear primary injector to put the connector on the inner side so it clears the oil injection nozzle. Without the EV1 -> USCAR adapter it would probably have fit fine in the original orientation.



It's kind of hard to see in that photo, so here's a photo of the secondaries:



I got the adapter height right on the first try. They fit very snugly with no wobbling, but also rotate smoothly with some effort.

Since these injectors are high-impedance, I needed to deal with the stock resistor pack. This is only required for low-impedance injectors like the stock ones. It's this big box that sits on the inner passenger fender:



There are 5 wires going into this connector. One central wire with 12V on it when key is in the IGN position, and then four wires that run through the resistor pack and to the injectors.

I needed to bypass the pack and tie all of the conductors together. I was hoping to find a clean solution but this connector is an odd one that I didn't have around. Conveniently this injector pack is a common part and I didn't feel too bad about snipping the wires and soldering them all together:



I did keep the pack and there is enough length that it's technically reversible. Then I added some zip-ties to keep all of this vestigial wiring tied-down:



Fun-fact: Other than the headlight relay and the few wires going through that grommet, all of these wires are no longer in use. They're either for diagnostic connectors, sensors I no longer need, or features my car didn't come with (auto-adjust suspension). I'm really glad they're hidden when the airbox is installed on top or else this mess would really bug me.

Now I'd like to write about the fuel pressure regulator here, but that's stalled since I don't have any 3/8" fuel injection hose. My usual place was closed today, as was my second-choice. Everyone will be closed Monday because July 1 is Canada day. I went to the local Canadian Tire and asked for some, and to my surprise they did actually carry it (albeit in pre-cut 2' sections only).

I drove all the way home only to realize it wasn't rated for fuel-injection pressures. This happens to me EVERY time I buy fuel hose and I never learn to check it before I leave the store.

Anyways, I go back to the Canadian Tire and they returned the old hose but didn't have any 3/8" fuel injection rated hose. The kid behind the auto counter recommended I try the garden section (there's no emoji that properly conveys "terror" so there's my best attempt). Fortunately a more experienced associate was there and immediately jumped in to correct him, but man, if there was no one around and someone tried using garden hose for their fuel system that could have ended in disaster.

So my only option was to buy an absurdly long roll on Amazon that should arrive before the 1st, and that gives me 25' of hose which should last me a long time. I wish I had known this before I disassembled my fuel system, but hey, there are worse things in life than having to wait a couple of days.

Updates to come as soon as I have the parts.

 

The fuel hose was supposed to arrive today, so I started out this morning by mounting the fuel-pressure regulator. Here's the regulator I picked up:



Aeromotive 13109, with vacuum / boost 1:1 reference, port for a pressure sensor, and dual inlets. There are cheaper regulators available but I knew I would want to use the sensor port and dual inlets eventually, so it made sense to just pick up a regulator now that has all the features I would need later.

One thing I noticed is that the threads looked really clean:



That on it's own isn't surprising, but I've seen some knock-off regulators with sketchy threads right out of the box. Yet another reason not to trust your safety to a no-name regulator.

Then I picked up these 3/8" (yes, 3/8", more on that after) barbs and installed them:



And then put this nifty little FPR adapter I found onto the secondary fuel rail:







It was advertised for Subarus, but I've seen similar regulator designs on Hondas as well so I assumed (correctly) that it was a common design for Japanese vehicles.

After that I needed a place to put the regulator. I didn't really want to put it on the firewall because the outlet is at the front of the engine and the hose would have to be very long. I also didn't want it on the exhaust side of the engine for safety reasons. But I found a convenient place where the big air solenoid for the stock ECU used to live, and made a simple little aluminum bracket for it:



Now normally I would connect the outlet from the secondary rail to the inlet of the new regulator, and the outlet of the regulator to the return line. But if you recall earlier I mentioned that I purchased 3/8" barbs. It wasn't just a simple error on my part when purchasing, but an error in measurement.

I noticed my fuel lines fit on the stock barbs at the fuel rails just a little looser than I thought they should. I thought this was because the new fuel lines my dad made when I bought the car (so not "new" but 8 years old) were slightly larger than stock, and the hoses were sized for those lines. I knew the current hose was 5/16" so I wanted to buy the next smaller hose which I determined (incorrectly) to be 3/8". I'm used to the metric system since I live in Canada, but it was still kind of sloppy on my part not to actually do the math and just rely on my faulty assumption.

Turns out it wouldn't have mattered since the stock lines are 8mm anyways, and the closest imperial size is 5/16". So if my lines feel a bit looser than expected it must just be my perception. I was able to reuse my old lines since they were only 2-3 years old and in good shape, plus I used two clamps at each fitting as is my habit. I'm pretty paranoid about fuel.

This does mean I need to wait a couple more days for the fittings to use the Aeromotive regulator, so for now I had to use the stock one. Injector Dynamics makes this handy spreadsheet that calculates the injector characteristics for you:



Stock static pressure without vacuum / boost at the nipple is about 37 psi and this spreadsheet doesn't accept values below 40. So I found the difference in dead time and flow from 43 to 40, and then extrapolated what the values should be for 37 (assuming linearity, which is probably an incorrect assumption). Then I used the voltage and small pulsewidths curves as-is. This is just to get the car driving for a day or two until I can properly plumb the new regulator.

I started it up, played with the Megasquirt's Required Fuel setting (basically a global mixture adjustment) until it looked about right and then went for a drive. First impressions are that it's a little smoother at idle and very light throttle. This is kind of in-line with what I was expecting, although I might see further improvement when I'm running 43.5 psi of pressure and using the correct characteristics from the sheet as intended. That is after all the whole point of this upgrade. I'm not going to do any extensive tuning with the stock regulator anyways since everything will change again once I'm running the correct pressure.

One other thing that I am curious to see is if the increased pressure in the rails helps with idle stability after hot-starts. It isn't like they were terrible before, but it was definitely a bit lumpier if I started it after a few minutes of heat-soak. Mazda had a neat solution to this which was to put a solenoid in the path of the FPRs pressure-reference, and then close this solenoid for 90 seconds on hot-starts. This was to prevent fuel boiling inside the rails (since pressure drops down to < 30 psi when the engine is at idle and the FPR is seeing vacuum). Raising the base pressure to 43.5 psi will also raise the pressure at idle and might improve hot-starts. I would be fine with it if there is no improvement at all, but it should be interesting to see what happens.

Updates as soon as I have the 5/16" barbs I need

 

the cheat code for high pressure fuel line is that BMW and Mercedes have 1m lengths of bulk 8mm fuel injection hose, and it used to be cheap
the downside is that they have this because its not very good quality, so like its not going to last 30+ years like the Mazda stuff

the Mazda stuff is amazing, but its also like $150 a foot

 

Yeah, I find the stuff I buy at my local place lasts about 5-6 years. The hose that's on there now is fine but I might look for a longer-lived solution when I swap the TII engine. Especially since it'll be subjected to more heat.

I'm thinking I'll get the best fuel line I can, plus add some of the heat and abrasion shielding sleeves I've seen on the market.

 

i'm also really curious about running higher fuel pressure. it seems like better atomization = more better.

 

I was thinking the same thing, except for two possible factors. First is that engineering is rarely that simple, so while better atomization is certainly better, more pressure may not equal better atomization. There might be some optimal pressure that atomizes the best and pressures above either aren't any better or are somehow worse. Second, higher pressure results in a higher flow rate for the injector. This means that at low engine speeds when injector duty is already short, it now has to be even shorter and the injectors might be less linear. So while it may help economy at cruise and overall power it might actually hurt idle.

I sent Injector Dynamics an email to ask what they recommend. I figure it's best to go straight to the source.

 

Wow, so Injector Dynamics responded incredibly quickly:

"The atomization on these is great at anything over 40psi, just don't go under. At 44psi the injectors will function at full optimization."

44 was the number I threw out there (actually 43.5 since that's where the ID725s flow 725cc), but it seems like there is no atomization improvement to be had by kicking up the pressure.

 

interesting, 44 it is then!

 

assumptions are the mine field of life.

it was very wise of you to ask/verify.
.

 

The new fittings arrived, so I installed those on my FPR and connected up the hoses:



The electrical tape on those two vacuum ports is temporary. The old caps split and the new haven't arrived yet, so this lets me drive the car until then.

Swapped out the original FPR for the adapter piece I showed before:



It works pretty well with two minor caveats:

1. The included o-ring is just slightly undersized. I swapped the o-ring from my original FPR (only a year or two old) and it felt much more secure.

2. The round fitting for the rail and the barb fitting for the hose both require thread sealant. I used Teflon tape to good effect, but there's nothing on it from the factory so it leaked out of both on my first attempt.

I did an impromptu alternator rebuild as well. My alternator was working fine but I heard a squeal on startup the last few days. Seems like the rear bearing was giving up, so I spent about 25 minutes swapping the bearings from a spare 3G alternator I had around:



I noticed the bearings are some brand I've never heard of (WTN, I think) so I'll try and buy some name-brand equivalents so I don't need to worry about this again. My alternator suffered a few more scratches but is now working fine:



The only thing I don't like about my FPR location is that the return hose hits the rear rotor housing:



I've got to do something about that lone wire too. It's just for the coolant temp gauge, but still. All of this wiring will be neatened up when I make a new harness.

With everything hooked up I was able to adjust the regulator to 44psi and update the ECU settings, then I started it up. For some reason I needed about 15% increase in fuel across the entire flow curve to put AFRs back around target (although less would have worked at higher flow rates). I'm not using more fuel with this setup (certainly not 15% more) so I assume this is something to do with my dead-time settings on the stock injectors being an educated guess of 1ms, which kind of skews everything. Now that I have accurate settings with the ID725s the new flow curve should be closer to the actual amount of airflow.

First impressions:

- Idle is definitely smoother. Nothing crazy but a definite improvement
- Transients are smoother.
- Car barely stumbles on hot starts after soaking for 20+ minutes. I think with some tuning of the ASE I can eliminate it completely. Higher pressure might improve this further, but it's good enough now and as discussed a higher rail pressure might make the injectors less linear at idle.
- It's easier to take off from a stop without as much feathering the clutch.

The biggest difference is that the car is happy at much lower throttle amounts and in the 1500-2500 rpm area where I've found the engine to be a bit lumpy in the past. Not that it ran poorly or anything, but it's noticeably smoother when I'm at say 5% throttle cruising along slowly.

I took a long drive and started smoothing out the flow curve even further (15% correction was an estimate, after all) so I might find more improvements are there for the taking. Once the flow curve is smooth I'll revisit all of the compensation tables.

I'm pretty happy with the results so far. There are already noticeable improvements and this prepares me to install an upgraded fuel pump when it comes time to swap the Turbo II engine in.

Until next time

 

This is less of an update and more of an informational post, and not even about Rx7 parts. But it has some interesting implications for my idea to use an electric air pump + solenoid for the AUX ports so people might enjoy it.

I finally caught COVID last week so I've been stuck at home, and not feeling well enough to do any meaningful work on my car. I did have a part arrive in the mail though. I found that there are plenty of electric air pump options out there and decided on a Toyota Tacoma pump based solely on cost. Full disclosure, this is a new aftermarket part, not OEM. Here's how it came out of the box:



It came with a little plastic dust cover for the inlet (bottom-most tube in this photo) and rubber isolators for the mount. My idea was to build a simple mount, add a tube from the airbox to the inlet, then cap the outlet with a small barb for the AUX ports and use a solenoid to vary the amount of pressure the actuators see. Since it's not linked to crank speed like the belt-driven pump it should avoid the issue I was encountering where pressure was linked to RPM and let me have complete load-based control.

The first thing I noticed was this absurdly large connector with absurdly large terminals inside:



Maybe I should have used a coin for scale. But it's really big. At this point I realized the pump probably draws a significant amount of current, which made we wonder why it only has 14 gauge wire. I know it's only intended to run for 90 seconds at a time, but come on.

The top screw comes out which exposes the filter housing:





The filter isn't necessary for our application since the Rx7 airbox has an outlet on the filtered side for the air pump. You can see the pump impeller peeking out from the bottom of the housing:



The housing comes off with 4 screws and then the impeller is exposed:





Definitely a different design from the Rx7 pump. The Rx7 pump is a rotary vane pump, similar to a power-steering pump if you've ever looked inside one of those. This seems to operate more like a water pump where there is a simple impeller.

The wear on the top of the impeller was there out of the box. There was some molybdenum grease on it, but there were also witness marks on the plastic housing so some wear was definitely occurring:



When the top housing is removed this rubber cap drops off of the motor on the bottom:





When you see the size of this motor you start to really wonder why they thought 14 gauge wire was acceptable. Also, the spade connectors:



I know this isn't OEM, but come on. Aside from being the wrong size terminal, how many amps are we sending through that tiny point of contact?

I can answer that because I tested it. 20 amps continuous, >20 amps startup. Not surprising that you need a lot of power to move significant air but one would expect a little more attention would be paid to the wire sizing. At that point I realized that if I was going to run this pump I would be adding 10 gauge wiring for it, but it became a moot point when I went to test it. This pump moves a good amount of air but it can't build pressure at the outlet the same way the rotary vane pump can. I think this is more to do with the pump design than with the motor sizing. Maybe the impeller type pumps simply aren't good at dealing with pressure on the outlet side. This pump couldn't even budge the AUX actuators.

It's also not surprising that I saw tons of reliability complaints when I searched for electric air pumps. This seems to be true regardless of manufacturer. I think the motor in these pumps has a hard life and gets pretty hot inside that rubber cap with no ventilation. Plus it lives under the hood of a car.

Either way the pump ended up being returned, but most of the other electric air pumps I see on the market are a similar design so I think they're mostly ruled out. It seems like Rx8 pumps might be an option, but at some point the cost of the air pump based solution reaches the cost of the linkage based solution I suggested in the past, so I don't think I'm going to go to the trouble of tracking down an Rx8 pump to see if it works any better. Whether I build out the linkage design or just wire the ports open is still up in the air (although my test shows the fully open ports only become efficient around 6400 rpm so I will be unambiguously down on power almost all the time with open ports, other than when flat-out at high rpm).

Not much of an update, but I learned something from it. Until next time