Hey all,

Pulled the engine out of my 1995 rhd FD after confirming a coolant leak into the front rotor housing. While the engine is off for a rebuild, I'm home compiling a list of parts/ maintenance that should be done now that I have all of this room for activities. My goal here is to follow up with a step by step of what I did and WHY, hopefully compiling all of the knowledge from these forums into an updated 2026 thread. With that has come hours of digging through threads, parts research, and talking to shops about what is best for my car. I bought this car to learn and that's 100% what I've been doing. However, I'm here because I want to do this RIGHT once.

My goal with this car: OEM+ is overused but you get the gist. I am not searching for HP numbers, just optimal power from a mild street port. I finally have my dream car and I want to drive this thing everyday and enjoy all that it has to offer. I am building this car to last but I am taking advantage of this opportunity to do all of the proper maintenance and upgrades that will keep this thing on the road for years to come. This car was also a 99% stock 1 owner car in Japan with 60k miles and I am not here to destroy that.

My plans:
1. Mild street ported engine - allowing the engine to breath better since it is already getting blown apart
2. PFC ecu - going to meet all of my needs for my goal
3. Simplified Sequential - I have already gotten personal with the rat's nest and I want the ease of maintenance
4. ACT HDSS Clutch kit

Things staying stock (for now):
Turbos, Intake, Intercooler, Injectors, fuel pump, exhaust (JDM DP & came with an HKS catback)

Things I need guidance on:
1. Simplified sequential - what can/ has to get removed and is it really as simple as the block off plate kit and using the diagram? I'll be including my journey with this since it seems a lot of threads died.
2. Gaskets - I've heard they all need to go and i've heard that most can stay. Which ones are actually safe to reuse?
4. Fuel pulsation dampener - removal seems to be dependent on hp numbers but I really don't want a fire
4. OMP delete - I already premix and I check the oil regularly. There doesn't seem to be a downside to keeping it

Any other guidance/ lessons learned to make this thing solid would be great before I dive in head first!

If there's some threads I missed that answer all my questions, I'm sorry. Just link them and I'll move along. I love this community and forum and I want to give back somehow to the next guy with a quarter life crisis.

 

3 years ago, I started off with much the same plans and facing a lot of the same questions.

Unfortunately, I'm not yet in a spot to share my experience. At least not in full through to the end. Despite starting in earnest 3 years ago, a host of issues stopped progress until just a few months ago. Right now I'm at the "everything's been removed" stage. Literally everything. At least forward of the cabin. I've gotten quite the collection of parts waiting and I should have the shortblock back from rebuild and be assembling the longblock in April/May. I've since changed plans a bit -- but still broadly similar to you, namely in keeping the Twins. In my case though, they're BNRs.

All that said, I would add one thing to your list -- SENSORS.

You've got gaskets on the list. And I would probably throw hoses into that same category. But, honestly, the pricing on these makes 95% of them no-brainers to replace. At least in my opinion. Any of the non-metal gaskets are, generally, reasonably-priced. And, personally, after 30 years I'd consider any non-metal gasket to not be re-usable. In my experience, on a 33yo car with an engine last reman'd 25 years ago (so probably didn't have much replaced at the time, as the car was only ~8 yo), pretty much anything that wasn't metal was in pretty dire shape. Hoses weren't in 'bad' shape per se, but had lost all flexibility so hose clamps weren't really doing a lot anymore -- at least once you managed to remove them from the permanently-indented hose. The hoses do add up I suppose but they're largely still available and usually reasonably priced -- at least by FD standards.

Sensors though... I've purchased replacements for all of mine. But that's definitely one category that some feedback/expertise from the guys here would be warranted if you're trying not to be wasteful. Some are pretty basic -- like $30-50. Not so bad. But then you've got some like Knock, Oil Pressure, Fast IAT, wideband (last 2 are more optional depending on your plans), and probably some others that can be $100-300/ea. Solenoids are similar -- though you'll be ditching almost all of those with the emissions delete.

Going back to gaskets, I suspect you're asking about those related to the Twins. As those can be ludicrous. You could spend nearly $1000 on just all those. The diamond-shaped ones on the engine side are likely re-usable from what I've gathered. Mine appeared fine. I did buy some from Mamba -- and they do appear significantly better than OEM for what that's worth. But those are the cheap ones. The expensive ones... I don't think anyone's gonna definitely tell you to, or not to, change them. N3B7-13-491A, the one on the downpipe side, seems the most likely to have blown-out and most recommended to replace. N3A1-13-710 and N3A2-13-710 the turbo-to-manifold gaskets are 'generally' considered re-usable. People have done it for decades... but it doesn't mean that yours will be. If your are unevenly compressed or clearly blown-out, then that would tell you definitively. Up to you on whether to roll the dice or not.

Sorta related to what you're asking about, but as someone who found this AFTER buying all the piece-parts, you might consider N3C1-15-010D (I'm assuming the same for RHD, no reason to think it'd be different). This is the ENTIRE water housing on the front of the engine. But, it includes OEM water pump, gasket, coolant sensor, and thermostat. So, for only ~$300, probably less than all those pieces individually, you get them all assembled for you AND a whole new water housing -- which, if yours looks like mine, is looking a little pitted from corrosion.

Great thread idea though. What you're thinking is a common plan, and it's great to both get everything together in one place and perhaps make it more pertinent to the current times where applicable given part availability/pricing being very different than when a lot of things you'll find on the forums here were written.

 

Well if the stars align and our timelines match up then we'll be throwing parts back on our blocks around the same time. Sensors are definitely one thing I hadn't thought of. I'll have to reassess everything I pulled off the block and give it a good look to see what's showing it's age from heat/ wear. I think my risk tolerance here is what's not gonna suck to replace once I drop the engine in. If it's in a truly despicable location, its getting replaced.

On the gaskets though, paper/ rubber are going in the bin. My biggest concern is the metal gaskets though but I'm going to take your advice and give them a thorough look over before they get put back on. Thankfully my water housing is in good shape, but I'll add that P/N to my long list of FD notes I've got going.

The more I look, I think the biggest challenge of this reassembly is going to be simplifying this rat's nest.

 

The good news on the sensors is that, all the ones I can think of at-hand at least, are all easily reachable -- but I'm far from an expert and I took this thing apart 3 years ago. Especially the most expensive ones -- knock and oil pressure which run about $200/ea (there are generic knock sensors for <$50 -- use at your own risk and make absolutely sure you're buying an OEM one if you buy online). They're right on the side of the block adjacent to the spark plugs. IAT is cheap at OEM (like $30 maybe), but the Fast versions (and PnP harness) that people often go with are fair bit more (like ~$100). It's on the underside of the UIM. Someone super dextrous may be able to manage without removing the UIM but I'm certain I couldn't. Oil level sensor is >$150 and, of course, super easily-reached at the oil pan. Oil Pressure and Oil Level OEM sensors are generally considered pretty poor sensors anyhow with the oil level sensor in particular being frequently just removed and blocked-off if it goes bad. Oil Pressure sensor was so **** that Mazda just removed both the sensor and the gauge from '96 onwards. You're definitely going to want, at the very least, either one or the other being functional.

And I personally 1000% agree on the Rat's Nest. Not looking forward to that at all. Even less so making it look halfway decent, as I want to minimize the appearance of any hoses left after deleting all the emissions.

 

IMO…
Stay with new STOCK hard seals, springs, seals and gaskets. Especially exhaust gaskets which are pretty expensive. Some have had success annealing the old stickers but they’re a huge PITA to do a second time if they leak. Your call.

Years ago I spent my money on a better SMIC rather than porting and had NO regrets. But then I also didn’t trust myself to do the porting properly, especially since I was using brand new housings. YRMV

Along with PFC for simplified sequential and emissions, double throttle and AWS can go.

I liked keeping the OMP and premixing at half rate. Never had issues with the cat and you won’t need the O2 sensor with the PFC, so no worries there.

Efini Y pipe if you don’t already have one.

Replace the old check valves with viton and silicon or viton vac lines.

My signature lists most everything you can delete

 

I think you have a initial good plan of attack. Being a 33 year old car, I have slowly replaced everything that moves, like bushings, pillowballs, wheel bearings, shocks and springs (now coilovers), waterpump, alternator, powersteering pump, AC compressor, belts, Twin turbos, engine rebuild, PFC, fuel injectors serviced, downpipe and full SS exhaust, brakes, rotors, all hoses, fuel pump, trans serviced (new synchros). The vacuum hose job enabled my secondary turbo to work properly. I just replaced one hose at a time with silicone hoses so I didn't get the routing confused. I would test the solenoids while you are in there with a 9 volt battery to make sure they are working properly.

 

I appreciate all of the help, definitely going to take time to go through a lot of that preventative stuff and I've got a good grasp on simplifying seq. now.

Unfortunately, sent my injectors off for cleaning (more preventative maint.) only to hear back that both of my primaries and one of my secondary injectors are tired and should be replaced. So this leaves me at a crossroad and I'm just looking for a little experience on my current options. I know the sky is the limit with how crazy you can get on the fuel system and I'm obviously not looking for crazy power. Just keeping in mind that I'm running stock twins, mild street port, and a Power FC, can another set of stock injectors and an upgraded pump keep up, or do I need to start looking at a step up setup? If so, should I look at FFE, RP, or the radium setups?

 

For the turbo system, I'll say that it's better to stick with the sequential system unless you must "simplify" for whatever reason. A set of working sequential twins is a great experience. If you're able to simply emissions items, that's less solenoids. If you can keep the twins sequential, new silicone hoses, solenoid valves, and check valves (from Dale, of course) will have that system working well for a long time.
I kept the OMP and premix 1/2oz/gallon gas. If you keep the OMP like you said, new OMP lines are a good idea.