I also mentioned a few weeks ago that I was going to share "an elaborate solution to a problem no one cares about but me". Recent events have shown me that it might not be just me that cares about it though, and I won't have time to write the massive post I was intending detailing some of the design. So here's a short overview instead, with more details about the production to come.

There are also probably forum rules about selling things, which I need to read and make sure I am in compliance. I am not yet actively selling units, so this post is purely informative. Everything following is subject to change, although it's basically completed.

I've made a PWM commanded Oil Metering Pump controller. You connect it to a PWM output on your standalone (unpowered, not powered) and make a map based on RPM x Load. Then whatever duty cycle you put in the bins, the controller will follow it. It has complete feedback control using the sensor in the OMP, with a mean accuracy within 0.65% of the commanded OMP opening. This lets you take any standalone ECU with a generic PWM output (basically all of them) and use it for complete control of Mazda OMPs.

I call it EZ-OMP:



It's not a very complicated circuit, and it would be easily replicated. So I have no problem showing a picture of the board here. The code is the complicated part anyways. An Arduino does all of the thinking, and then I have some additional supporting hardware for a few other features I will explain below.


(The above case is a prototype. I have since altered some print settings for better fit and finish, but it is functionally similar).

The case has changed a little bit since the one you see there, including a clear window for an activity light. The Deutsch DT connector is waterproof. Because demand is unknowable (although it definitely seems to be more than I had expected), I will need to make them to order. I also included a TPU seal to make the entire case water-resistant. I am not calling it water-proof since I can't possibly test each unit underwater, but the unit is designed for in-cabin installation anyways.



There are two M6 mount points so it can be easily attached to an ECU panel or other flat surface of your choosing.

So far it has been tested with an S5 OMP and works great. I am obtaining an S6 in short order to test that as well. It should work with any and all OMPs except Rx8 because I built-in an auto-ranging function, but I won't be promising that until it's tested with the various types.

Feature List:
- Full PID feedback correction.
- Auto-ranges OMP sensor at each startup (should make it compatible with all types of OMP except Rx8).
- Error detection (in case of stepper not reaching target, disconnected sensor, etc) with buzzer for error codes.
- Error light output, triggered with either of the above errors & if board is unpowered when the ECU is turned on (burnt fuse, etc).
- Limp mode output. Connect it to the tableswitch input on your ECU and use it to command a reduced boost pattern if your OMP fails, for example. Triggered when the error light is triggered.
- Park function that moves the OMP to maximum when you turn the engine off.
- Requires only the one ECU output (and optionally the input for the limp mode trigger).
- Deutsch DT connector with included pigtail.
- Water-resistant case.

I started this as a school project and as a solution to my OMP problem, and then at some point I decided to go all the way and make it a complete product, even if it was only me who wanted one. But now it seems like there might be more interest than I thought, so after I finish rigorously testing my work I will be offering units for sale. So far, no prototypes have failed. A hardware warranty will be offered on the EZ-OMP unit and pigtail; no warranty is offered or implied on your ECU, OMP, engine, or anything else other than the EZ-OMP unit. There are far too many variables in play for me to warranty anything other than the unit.

There will be a lead-time, as they will be hand-assembled and made to order. Unless volume is massive and economies of scale kick in, there is no way that having units pre-built will be economical.

I also don't know exactly when they will be ready for sale, as I'm currently finishing my exams and I also work. It's 95% of the way there, but we all know that the last 5% is the most time-consuming.

Price TBD. All of the above may be subject to change at a later date.

Hope this has been interesting. More details to come as soon as I have them.

Here's a screengrab of me datalogging with one of the prototype units:


You can observe the commanded duty in Tunerstudio on the right hand side, and a Hyperterminal capture of the output from the valve on the left.

 

When I saw you post in the thread in the engine management forum I wondered if this was the project you had alluded to awhile back. Very cool. I'll be keeping an eye out for the for it.

 

agreed. I may have theroretically just purchased a 20B, and I'd love to keep the OMP functioning. I was considering doing the same thing, but looks like you've done most of the heavy lifting already. I'll be keeping an eye out for when these go on sale.

 

Let me know when you're ready to order and I'll give you a special price. I haven't had an opportunity to test it on a 20B pump, so it would be great to have someone try it out and let me know if it works. It seems like the pumps are mostly the same up to S7, then S7 and S8 are a bit different. I'm assuming the 20B pump is similar to the 13B-RE pump, which probably makes it electrically similar or identical to the S5 pump. My controller should work for any (except Rx8), but I can't claim that it will until it's tested.

It will be a few weeks at least until I have all my ducks in a row. I will probably be ready to ship out a few units to early adopters before then (one is already spoken for) but I'm waiting on an S6 pump to test with before I ship any units. Luckily j9fd3s came through with a pump at a great price (thanks again!) so I should have one in-hand soon.

 

absolutely. I got a few weeks before it gets to me anyways.

 

Got the 20B in the other day. would love to help out however I can with this project.

 

I appreciate the offer, sent you an email

 

I haven't really worked on my Rx7 much lately. It's been pretty chilly and it lives outside, plus the new semester has started. But this morning I had time to address something small that's been bugging me a little bit.

When I installed my MS3X, I didn't actually connect the fuel pump wire to anything. Since the Rx7 fuel pump is switched in the MAF sensor (more on that in a minute), I didn't actually have to. My MAF isn't actually doing anything anymore since it I am running speed-density, but the switch inside still does it's job and switches the fuel pump on.

Except, this means that there is no fuel pump priming with key to ON. See the following:




As a consequence of being an early fuel-injected car, the Rx7 implements the fuel pump safety shut-off function in a kind of unusual way. Instead of letting the ECU control the fuel pump and shut it off when there is no crank signal, this function is shared between the MAF sensor and the relay shown above.The Circuit Opening Relay (COR) has two coils inside. One is powered when the key is to START. The other is powered when the MAF flapper door is open. This way when the car is cranking, fuel is supplied, then when it starts the MAF is open and fuel is still supplied.

If the car is crashed and the engine shuts off, the MAF door closes and the fuel pump deactivates. This is to prevent a safety hazard caused by pumping fuel after an accident. My problem, however, was that there was no prime function and the fuel takes a little while to pump. This means that starts took a second or two longer than usual.

Was it a big deal? Not really. But little deals add up and make the car less enjoyable to drive. My idea is that my mother should be able to jump in the car and drive it without having to warn her about all the "quirks" beforehand.

Turns out, the solution was fairly simple. The MAF flapper door switches ground (E1) on the COR. The MS3X switches ground on the fuel pump output. So I can just de-pin the stock wire in that position (from the harness side):



Crimp a new pin onto the fuel pump wire from the MS3X (Yazaki .250, I think, had it in my basement):



And install it in the position E1 used to occupy:


(I will insulate the old terminal and tie it back when I neaten up the wiring)

Now the MS3X will control the fuel pump, including a prime of 3 seconds on startup and shutting the pump off if it doesn't see a crank signal. No safety compromises whatsoever.

But I still had a fairly slow startup in the cold. Today is just a bit below zero here (0C = 32F), and it was cranking 4-5 seconds before starting. Now that I know it's priming properly, there had to be another culprit. These are the Priming Pulse & Cranking Pulse tables I was using:



The priming pulse is one single injector pulse the MS3X fires after priming, to put some fuel vapour in the runners.

The cranking pulse is a percentage adder on the existing fuel calculation, used only when cranking. Due to the low engine speed and cold temperatures, I figured I had to add some more fuel in. After playing with the settings awhile, I tested out these values:



I increased the prime pulse from 10% to 30%, and then way, WAY upped the cranking pulse settings. And it started right up. I didn't expect that it would need that much extra fuel (~300%) when cranking for a quick start, but I can't argue with the results.

I'm going to keep playing with the settings and dial it in a bit more, but its 95% of the way there already. Trouble is that you only actually get to tune a true cold start once per day. Even if you shut it off immediately and make changes to the settings, you've already altered things by warming up the combustion chamber and misting fuel in the manifold. Going to have to keep at this once a day, and try to get some varying temperatures.

It doesn't usually get colder than -35C where I live, and even that happens for only a few days a year. For reference, -40 is where C and F are equal. It's unlikely that I will actually ever start my car when it's that cold out, but again, my philosophy is that my mother should be able to start and drive without any hiccups. So if the opportunity presents itself, I'm going to try and tune for a perfect start regardless of temperature.

Until next time

 

its one of the more rewarding things to tune, imo. its also kind of a lazy Saturday hang out in the garage thing. in California, the other CA, i don't bother with anything under 0 F, lol

 

One interesting thing I've seen online is that some people think cars tuned on standalones "don't start as quickly" as a stock car. Which I suspect means that they had someone tune it for them, possibly doing power runs on a dyno, but haven't actually spent any time on the cold start or warmup settings.

This makes sense. It isn't really practical to expect a tuner to work on that. It's just interesting that it seems to be accepted that the car just won't start as fast, when there are a wide variety of settings designed specifically for tuning that.

You guys are spoiled with the weather over there! Honestly, I don't even mind the cold or the snow. Except snow means salt, and salt means I won't drive my Rx7.

 

ive seen some bad ones too, its like they did the three dyno runs and called it tuned

 

I've been successfully ignoring some small exhaust leaks for awhile now. I've known about them for a long time, but didn't bother fixing them because I had some vague notion that I would replace the faulty section with a set of headers in the near future. Then I picked up the Turbo II swap parts, and again decided not to fix it because I'll be replacing the faulty section with a downpipe.

However, I determined I no longer wanted to arrive at my destinations wearing Eau de Rotary. So $44 later (not including welding materials) I have everything I need to fix the problem.

The problem is manifold (pun intentional, the actual manifold is not the problem). First is that the flange between the downpipe and the catalyst is warped, and causes a leak. Adding that flange was the first welding project I took on (PO welded the entire exhaust into one piece):



You can see the black soot where it was leaking.

Second, it doesn't line up very well. This means you need to start the bolts in all of the exhaust flanges without tightening them, and then slowly tighten them in a criss-cross fashion to get everything to line up. The flange is slightly rotated from where it should be, and was also a tiny bit too short so that it tries to pull the rear sections forward when tightening. As a consequence of that:



Problem three, the downpipe flange won't seat evenly due to the skew on the catalyst flange. This is near the stock O2 location which I am using as well, so it may also contribute to inaccuracy in the AFR readings.

To fix it, I first pulled the downpipe:



I removed my well-used thermal wrap. Word to the wise, don't wrap anything that isn't stainless or it will rust to nothing. I forgot to take a photo, but you would be shocked at just how much of this pipe flaked off. The pipe is made of thick tubing and ultimately it's temporary, so I will be wrapping it again at the end of the project.

Then I started on the solution. I'm adding a flex-section, purely to make installation easier and soak up some vibrations. It shouldn't be necessary on a longitudinally mounted engine, but the flex-section was $21, so it can't hurt. I also got a set of v-bands with stainless clamp for $23. I first tacked one V onto the flex-section:



I'm not a great welder, but for this project I swapped to my solid-core wire and shielding gas, and the results were much improved. I can hear that nice "bacon-sizzling" sound that tells me the settings are close. Unfortunately I only had 0.023" wire on-hand, so I had to make a few passes and it ended up a little ugly.

Then I offered it up to the downpipe and made a mark where I would be cutting:



After cutting it, I turned my attention to the catalyst side. The flange looks crooked, but that angle is actually intentional. If it was a bit further, it might actually have sealed:



Zipped it off and ground a bevel in with the flap wheel:



This picture isn't complete, but I went and stitched opposing sections of the v-band onto the pipe. My technique needs work, but I'm improving (trust me!):



Once I finished welding the band on and let it cool, I clamped the flex-section onto the catalyst:



Then reinstalled the downpipe, and...



There's a huge gap. I should have anticipated this, since the exhaust was a bit too short to start with. I could have saved myself time and had a neater result if I left 1" extra and trimmed it down later, but I didn't. So I ended up slipping in a small section and tacking it together on the car. Then I pulled it back out to finish the welding.

After that, it was time to add an O2 bung. AEM recommended I place the sensor 18" from the exhaust ports, and 36" if high EGTs are expected. I'm somewhere in the middle of those two measurements. The stock location is around 8" from the exhaust ports and that probably isn't great for the sensors.

X marks the spot:



I drilled a pilot hole, but I don't have a large enough bit to get it to the final diameter:



To be continued

 

Continued:

I ended up using a carbide bit on my die-grinder to widen the hole, and then popped the bung in and welded it:



It actually looked pretty good on the first pass, but then on the second and third I started to lose confidence in my welds being gas-tight, and reverted to the old "pile it on and pray" method. My original pass was probably sufficient, but it isn't an art project. I want to get in some more practice before I make the downpipe for the Turbo II engine. That part will have to be custom since I want to run a catalyst, and I also want to make it out of stainless to match my cat-back.

On re-installation I encountered a pretty major issue. One of the nuts for the downpipe crossed (I think I had the wrong nut, but that's beside the point). Weirdly it went on pretty smoothly before getting stuck right as the threads started to emerge the other side, and then got stuck further on removal and twisted itself.

I tried removing it by hand, but was unsuccessful. The Ryobi electric impact removed it alright:



... but it took a section of stud with it as it twisted off.

The other stud is okay. I think the best way to fix this (short of digging out one of my spare manifolds somewhere) is to run a tap over the threads and try to clear the damaged section. I already have the M12x1.25 die, but it is larger than my die-holder so I'm waiting on a new one before I can proceed.

Worst-case scenario, I may have to dig out my spare manifolds and see if any of them still have undamaged heat-shield mounting holes without bolts broken in them (I highly doubt it). At least I didn't break any of the studs on the engine

Until next time

 

When we left off, I had a pretty badly damaged exhaust manifold stud to deal with. I was waiting on a die-holder to arrive today, but I realized that I probably wouldn't have enough clearance between the die-holder and the bell-housing to use it effectively. So I just slid under there with a file, a M12x1.25 die, and a set of vise-grips and went to work. After filing any protrusions on the end down and getting the die to thread on, I slowly threaded it down about 30 degrees at a time using the vise-grips. I wasn't taking any chances with this one, so I also spent a lot of time backing the die out and making sure it was clear. Luckily, it paid off:



It looks a bit sketchy, but the new nuts I purchased went on smoothly. I also grabbed a new gasket:



The factory gasket is a steel design, which makes it reusable. Unfortunately mine has also eroded at the location of the exhaust leak, but at $8 this aftermarket one isn't too big a gamble.

Then I re-wrapped my downpipe so it can start rusting again. The exhaust wrap seriously cuts down on heat transfer into the floor of the car, so skipping it wasn't really an option to me. I lost the lock nut for the v-band clamp, so I installed a regular M8 nut I had around:



Hopefully it doesn't loosen up. I'll have to check it periodically to see what happens.

One thing I've also seen people do online is use wire to tie the wrap-ends tight. While this works, it also leaves a sharp end waiting to poke you or the next person to work on your car. I always use a set of large worm-gear clamps, and they've worked very well so far.

The location I picked for the wideband O2 sensor worked out great:



Plenty of clearance, and I can zip-tie the cable to the split-air pipe to keep it neat. I'm not worried about the heat damaging the sheathing on the wire as it's designed for that, although I'll have to check in on those zip-ties and see if they survive. The split-air tube doesn't get nearly as hot as the rest of the exhaust. I know they make PEEK zip ties, so I may need to get those in the future if the current ones melt.

Then I needed something to plug the stock O2 location. I didn't have a plug, but I did have an old narrowband sensor laying around:



After double-checking my work, I started it up. It's definitely much improved, but it still leaks a tiny bit. I'm not sure if it's from the manifold to downpipe flange, or there may be a leak between the manifold and the engine (I reused that gasket awhile back). The main problem though was the big leak at the catalyst, which is now 100% fixed. I don't even smell the remaining leak, only hear it.

The flex-section is soaking up a bit more vibration too. While this is nice, the stock exhaust doesn't have or need one. This makes me wonder if maybe I have one or more issues causing vibration at low rpm. My car likes to idle around 12.4 AFR, so I'm wondering if maybe one or more of the injectors are a bit wonky and causing inconsistent fuelling. It smooths out by 1200 RPM or so and then feels fine thereafter.

The O2 readings might also be a bit smoother, but I didn't notice any significant change in readings so maybe it's just me.

It was unseasonably warm today so I also took the time to let it warm up 100% of the way and spend some time refining the tune. I was able to pull some fuel out at idle after moving the injector timing earlier, and less fuel consumption is always nice. And after playing with the cranking settings, when warm it now starts on the first jump of the tach (tach is driven from the coils, so this means it starts when the plugs first fire). Not to toot my own horn too much, but I'm very happy with it.

Until next time

 

Progress has been a bit slow. I've been working on some other projects since winter is mostly down-time for my Rx7, and it's still too icy for me to do much. Recently I've been doing some Rx7 related parts-chasing, so this might be of interest.

A few days ago a friend of mine posted a picture of his FC's transmission cross-member on Instagram. In it, he mentioned that he thought he had installed a part in the wrong place. Looking at it, I realized something; I didn't have one. Not only that, but there are supposed to be two of them.

The part is a small washer that sits on the transmission Y-bracket, with a large raised brim. My friend found the relevant part diagram for me super quickly, and here it is:




Amayama lists the part at $3, and calls it "transmission mount bracket weight". It looks like it's just a chunk of metal, and probably has something to do with vibrations. If I'm speculating, an engineer who knows a lot more than I about the issue probably calculated that extra weight would help reduce vibrations by 2% or something.

Even more concerning is 3975-39-045. I also don't have any of those installed on my car. Just when I think I've replaced everything the previous owner tossed, another missing part rears it's head.

This is listed as "stopper casing", and I think it's mostly for safety. The engine mount has an upside-down cup shape. If the rubber isolator puck were to shear off, I think this stopper is just designed so that the upper cup catches on it and retains the engine in the car. It probably has little to no isolation benefits. I can find very little reference to this part online, implying that others probably throw them away or don't replace them either. In my case they are outright missing.

Is these parts important? Probably not.

Am I going to spend way too much time chasing some down and installing them anyways? Absolutely.

The transmission weights were fairly easy. I went to the shed and dug through the boxes and boxes of old parts I have, and managed to come up with three of them:



Everything I take off of the car goes back on unless there's a reason, so these must have been in a box of parts I purchased. I also found out I had a set of DTSS eliminators. Who knew?

After stripping the rust using CLR and the ultrasonic cleaner, I ended up with nice clean surface:



And then finished it with POR-15:



POR doesn't leave the nicest finish, but it's currently below the minimum temperature for spray-paints, so since I wanted to make progress now POR in the basement was my only option.

Then, on to the stopper casing. I didn't have any in the shed, and I didn't see any on my Turbo II engine. After contacting my usual dealership, they told me it would be $29 per and a few days wait. I picked them up yesterday afternoon, and:



They're crunchy. Like, really crunchy. I first thought this might just be dry-rot. But then on a whim I checked my Turbo II engine again, and it turns out it DID have the stopper casings:


(Remember when I said the car this engine came from was in a serious crash? That bracket is supposed to be straight).

It's hard to tell from this angle and the garage lighting is a bit poor, but I think the stoppers might arrest movement in the rubber of the mount a bit as well. The base of the cylindrical rubber puck sits pretty close to the inside of the stopper
The rubber is surprisingly pliable still, albeit a bit loose in one place. I think the new parts I purchased just came from a bad batch, where the rubber pour was not properly formulated. When I went back to the dealership I asked if it was possible to request a set from a different batch, but as expected that isn't really a possibility. So I will have to be happy with my refund.

I decided to do my best to restore these ones. The main problem is rust, although in one place on one stopper the rust has loosened the rubber casting from the metal cup. I started by dealing with the rust:



I scraped away the loose rust and then used the Metal Ready that comes with the POR kit. Metal Ready seems to be just phosphoric acid, so it removes much of the rust and then converts the remainder into a paintable surface:



After waiting for the acid to do it's work, I again cleaned the surface and then applied a few coats of POR-15 over a few days. It takes about 5 hours between coats and also the part needs to be rotated, so it was slow going. I ended up with a nice tough surface on both sides of the stopper:



There is no good way to fix the loosened rubber, but luckily it is only loose in one location. You can see it in along the top rim of the leftmost stopper. I injected some RTV into the cavity and used two zip-ties to hold the rubber against the stopper. Then I worked some RTV around the inner brim of the rubber where it meets the cup as reinforcement.



It's not really a proper repair, and frankly I'm not happy with it. But since this part seems to be a safety backup anyways rather than a functional piece, I'll accept it for now in lieu new parts. It should still function perfectly fine as a backup should the engine mount tear (not that this is a likely scenario anyways).

The only other repair I can envision would be to burn and then blast the stopper cups clean to bare metal, build a cast in the negative shape of the rubber bumper, and then pour urethane to recreate the shape. Then coat any exposed metal of the cup with paint. While this is certainly achievable I don't think I'm going to worry about it.

As soon as I can safely lift the car I will install the weights & stoppers to see if there is a difference. I anticipate no change, but it will have been worth it either way.

In other news I was finally able to get a Turbo II hood:



On the upside it's red (on the bottom anyways), aluminum, and complete. The price was right. It's also a JDM part and the underhood stickers are in Japanese, which is kind of neat.

On the downside, I have quite a bit of work ahead of me. I don't want to settle for less than perfection on this one, so it's going to wait until I have a couple days off in a row this spring once the weather is warm enough for bodywork products. It's nice to have found one though. The hardest part of owning an old car is always chasing the parts. The remaining parts for the swap can be purchased over the counter from Mazda or from other vendors, so from here on out I can work at my own pace.

Until next time

 

So, I am quite sure my TII has never had those. I certainly don't remember them when I took the engine out or put it back in. Hmmm, who knew?

 

Loved the read and will definitely be using this as a guide for my S4 Vert!

 

Thank you! Make sure to post a thread about your vert when you get a chance

 

I haven't posted in awhile because I haven't really done much Rx7-wise. I've been spending my time on other projects, and frankly my Rx7 has been working fine. There are exactly three things that have happened with it, so I figured I'd make a brief update to show them here.

First, I finally addressed my speedometer cable issue. When I replaced the speedo-drive seal awhile back, I apparently didn't actually press the seal down onto it's shaft. This led to it not actually sealing anything, and the transmission fluid seeping up through the cable into the back of the speedometer (and consequently the back of my dash). Not a fun time. It also led to the speedometer sometimes jumping up higher than my actual speed. I assume this has something to do with the weight of the little drum inside being thrown off.

I had fixed the issue with the seal, but fluid kept coming out. It turns out that cable holds a lot of fluid. First things first, I had to clean out the instrument cluster:









This stuff gets everywhere. Just remember, this is about 1/10 of what was soaking the back of the dash...

The speedo itself had a lot of goop in it. The gear at the bottom is the area where the reed switch for the VSS signal goes...





There's a reed switch under there, trust me!



I cleaned everything using carb cleaner. I couldn't think of a better solvent or a better way to clean the inside of the metal drum thing. It worked very well, but a warning for anyone else who does this, it will absolutely dissolve the paint used on the odometer numbering and on the speedo face. The only casualty of my repair was some smudging on the "3" in the 1000s column of the odometer, so I'm fine with it. And after all that I forgot to get a picture of the cleaned reed switch.

With that cleaned and reassembled, I needed to clean out the cable. It turns out it's actually very easy:



The cable itself pulls out from the transmission side:



Then I let it soak in carb cleaner for awhile, and spent the time scrubbing the outer sheath:



The stuff that came out of the cable was pretty gross:



Then I hung everything up and let it air dry for awhile:



And reassembly was the reverse of removal.

A but underwhelming since nothing has changed, but it was worthwhile just to stop transmission fluid dripping onto my shins.

To be continued.

 

I have a spare cluster if you need anything, let me know.

 

Continued:

The next thing I did was an impromptu roadside repair. The on-ramp I was going to use to get onto the highway was closed, so I used the access road running parallel to it. At some point the road turned away from the highway, and then into dirt. Of course that's the moment my Rx7 decides to quit on me:



Not a fun place to break down. I had cell reception, but otherwise there was not a soul around. So I got to diagnosing.

Engines need air, spark, fuel and compression. It was reasonable to assume I still had air and compression, and losing all spark at once would be a bit odd. So I started diagnosing the fuel and I realized my fuel pump relay that I added in the rear wasn't clicking.

I first swapped out a spare that I had laying around:



Nope, nothing. Then I realized something:



The relay and socket I had installed came as a kit. I guess whoever did the crimping in the factory that day wasn't doing a very good job.

One tool I didn't have at the side of the road was a crimper. So instead I straightened out the wiring a bit and jammed it back into the crimp, then the crimp back into the housing. Then I used a small section of the green wiring to wedge the wiring in, and some harness tape plus a zip tie to hold it all together:





It was good enough to get me home, and then when home I replaced the crimp terminal. I also flowed some solder into all the terminals as insurance. All in all it was <10 minutes to get back on the road, so I'm glad I was carrying some basic tools and supplies.

One more little project to come momentarily.

 

This last project probably goes beyond "minor maintenance" but it only took a few hours so I'm lumping it all together.

Occasionally I would get a whiff of fuel from the rear of the car. This was more frequent on hot days, but sometimes weeks would go by without smelling anything. I had inspected multiple times and found no issues, so I chalked it up to the fuel tank venting pressure or something.

This weekend I was pulling into the driveway and I noticed the smell was a lot stronger than normal. So I took another look and still found nothing amiss from the outside. But after pulling the access panel I found a rust hole through the steel breather tube:



It's under the tape in this photo, as I wanted to minimize the fumes escaping. Here's a close-up I took afterwards:



Surprising that the fuel smell could be so strong out of such a tiny crack.

Anyways, I needed a new part. Unfortunately it's NLA from Mazda, and nobody I know locally has one. Someone was able to refer me to someone who may have one, but he's out in Guelph which is about 1 1/2 hours from me (one way). So instead I figured it would be faster to just fabricate a new part.

On removing the old part, you can see it was pretty crusty.



It also has this sock-thing on it, which goes on the filler side of the tube.



Looking down the sock, I thought I might have bitten off more than I could chew. There is a little one-way valve inside, which would have been beyond my ability to replicate:



Conveniently it's a removable insert though:





I got the materials next-day shipped from Amazon. One scratch-and-dent exhaust tube (1.875" OD), and another steel tube for the breather (5/8" OD):



Then I cut the tubing to the appropriate length:



And rolled beads:



I used an Amazon bead roller for the larger tube. I do not recommend it, since it doesn't have any adjustment for the backstop and it causes the bead to drift around a little bit. Probably fine for intercooler pipes, but really not a great tool.

The smaller tube was too small for the bead roller as well (advertised for 5/8" pipe, but they didn't specify ID or OD). I ended up heating the ends with a torch and banging them down onto the end of the vise handle to flare them out just a bit.



To be continued

 

Continued:

I cut and bent some metal brackets to hold the tubes together, then de-burred everything and aligned all the parts:



The two pipes are not directly parallel, so I tacked it together and then massaged the brackets until the angles were correct. Then I finish welded it:





My welds got a bit messy due to the confined space, but overall I'm fine with it for a part no one will see.



I'm pretty happy with how it turned out. The two parts are functionally identical. Regrettably only the breather tube is stainless, so I did have to find a way to prevent rust. Electroplating the part was an option, but some of the parts I have plated in the past haven't lasted. So instead I just opted to paint it:



Then the insides of the tubes got a coating of motor oil before installation. It doesn't see a lot of moisture, so hopefully the gasoline coating the inside of the tube periodically will be enough to prevent it rusting from the inside out.

I forgot to photograph the little valve being installed, but basically I just notched the end of the tube in a few places to let the valve slip in like it did on the OEM part and then reinstalled the sock. Then the whole thing got reinstalled into the car. Again, underwhelming since the car functions the same as before. But I saved myself some time and money driving all the way out to find an OEM part, so I'm happy with it overall.

That's it for now. I have a few things on the go but no other completed work to show yet. Until next time

 

Speaking of electroplating, I just found a local place that may be my new favorite. I took a bucket of hardware to the(12lbs) and it's going to cost me the minimum invoice amount of $145US to have them done in yellow zinc. What I found out is that minimum invoice amount covers about 300 lbs of material...

I'm gonna have some fun with this.

Also nice work on the pipe!

 

I need to try and find a place locally that will do that, then get all my hardware and fasteners together and send them as a batch.

Unfortunately that also means disassembling the entire car to do so, but that's a bridge I'll cross when I come to it