Rotary Resurrection - Tech Section
93-95 Emissions removal AND full non sequential conversion

I am covering full emissions removal/blockoff plates as well as full NS conversion at the same time. It really doesn’t make much sense to just do one or the other…the real aim of this work is to simplify the engine and engine bay. Doing just blockoff plates, or just nonsequential, does not accomplish this fully, so in my mind, it’s best to either leave the engine stock (sequential with emissions) or remove it ALL at once.

When I refer to emissions removal, I generally get rid of everything on the engine not needed to run, even though they may not be emissions parts. Some of these parts can be left in place while others are removed, but this writeup shows you everything that can be removed while maintaining the running of the engine. Some users may want to keep the cold idle thermowax and coolant lines, and/or BAC valve (to help with idle under load). I find that a healthy engine with properly adjusted idle (I sometimes bump mine up to 1000 or so) has no problems running normally without this. You can also remove your oil metering system and run premix at this time for even more simplicity, but I don’t normally consider this part of emissions removal.

You’ll need plenty of vacuum caps in sizes 5/32”, 1/4”, and 3/8”. Also a tube of ultra black sealant or equivalent (permatex), blockoff plates, 5/16” fuel injection fuel line (about 5 foot), hose clamps, and a few feet of 5/32” vacuum line and some tees/splitters. I use jb stick weld, not the liquid kind, but the putty type that you mix with your fingers, for the holes left in the TB by removing the throttle plates. Some more paranoid individuals might wanna take the extra time to tap and use metal plugs instead, though I’ve never had an instance where the jb weld came out of the hole (I pack it in well, and leave a lip on each outside edge).

Start with the engine stripped down, after removing the UIM, turbos, vacuum rack, etc. Use the engine teardown writeup elsewhere on this site to help you get to this point. I am performing the work on the stand after a rebuild, but this job can be done in the car. Removal of the turbos is the hardest part of the conversion. IF you want to go to premix now is also the time to remove that stuff and block off the holes as well.
After removing the studs and gasket material, install blockoff plates on the LIM for the EGR valve, ACV, and split air pipe (if your plate kit came with one for it). Sealant is best suited for sealing these, as gaskets may not do the job since the plates can warp slightly.
Assuming you’re removing the thermowax and associated coolant lines, we’ll block off these coolant ports on the rear iron and top of waterpump housing. To do so, I drain the coolant (obviously). I take the tube of ultra black sealant (this stuff dries very strong) and inject some into the nipple, enough to penetrate all the way down. Then I take the large vacuum cap, and inject a little into it as well. Put the cap on the nipple, and use small hoseclamps to tighten it down. Don’t refill the coolant for a couple of hours, to give the sealant time to dry. The sealant is important, the vacuum caps are not rated for high heat or pressure, but the sealant keeps coolant from making it’s way to the cap (or much of it, anyway). The cap keeps the sealant from being pushed out of the nipple, or developing a leak. I use these on my own cars with no issues, but you may want to check and replace them about once a year. Alternately you can consider packing the nipple with jb stick weld, which would negate the need for the cap and clamp.
Cap off the injector bleed nipple, and run about 8” of vacuum line from the other nipple on the LIM. This hose will serve as the fuel pressure regulator pressure reference later.
The oil injectors each have nipples on top. In stock form, these nipples draw air from the primary turbo compressor inlet. This is simply a place to draw fresh air from, which is neither boost nor vacuum. You can elect to tee them together and run the feed line to it’s original source on the primary turbo inlet, but I personally tend to leave them open (just as they are) since the amount of unfiltered air they draw in is minimal and I feel it makes for a tidier install without the extra hoses. The engine will run the same regardless of what you choose. IF you want to plumb them as they originally were, tee them together and run a length of about 10” of hose in the front.
Install fuel rails, taking care to properly seat the “insulator” orings between the lower rail and the block. I find that using hylomar or other tack agent to hold them onto the lower rail before installation on the engine works best. Connect the vacuum line to the FPR on the secondary rail. Don’t forget the black plastic spacer that goes under the primary rail.
Run new fuel line and install clamps. Leave about 2.5 feet of hose for each rail. These will go directly to the firewall connections later.
Lay on engine harness. Connect primary and secondary injectors (white/beige tape by a connector indicates FRONT), fuel thermosensor, water thermosensors, OMP (if being retained), knock sensor, rear iron coolant temp sensor, and crank triggers.
On the back side of the vacuum rack there is a removable bracket that used to hold the coils.
Bracket removed… (you can also cut off half of the bracket that is unused for cosmetic purposes)

Bolt the bracket in place on the rear rotorhousing, with the harness routed underneath, and the ground wire bolted in place.

To run nonsequential on a stock computer, you have to run resistors in place of some of the solenoids to avoid computer codes and a CEL. With a PFC this is not necessary. You need 330 ohm ½ watt resistors from radio shack, as well as male terminals.

Make the resistor in the shape of the plug…
They go on all 8 of the colored square plugs on the harness. The oval plugs do not need resistors.
I usually put a piece of tape over them as insulator to prevent shorts…
Install coils. You only need the one rear bracket to hold them in place, but if you’re really picky you can also cut off the front part of the bracket from the old vacuum rack and use it.
Place a cap on one of the 2 nipples on the oil filler neck.

 One nipple must remain open, vented. You can vent this one of several ways.

You can route it to the original destination, which was the primary turbo inlet. You can leave it open, but if your turbos are on their way out, you might get some spillage out into the engine bay after a hard run, sometimes old turbos pressurize the oil system under boost a bit and cause it to spray out of an open nipple. You can run a hose from the nipple to the bottom of the car, so that if any spillage results it goes on the ground. Finally you can run an oil catch can and route a hose from the open nipple to the can.

Oil filler neck installed…

Cap off all the nipples on the UIM except those for map sensor, and the 2 on the passengers side. Remove the AWS valve and supply pipe, studs, and install blockoff plates.
Remove throttle body.
Remove double throttle plates, shaft, and actuator, Plug the hole left in the manifold with jb weld or tap and install a metal plug. Some blockoff plate kits come with a plate for this as well.
remove throttle body coolant hose…
Remove thermowax
Remove TPS (make match marks before loosening adjustments) and bracket underneath.
Remove cold idle cam and spring
Replace TPS, BEING CAREFUL that the flat sides of the TPS rotor butt up against the tabs on the shaft arm. To do this you’ll have to lay the TPS on the bracket, then turn it until the tabs hit the TPS rotor, then install screws and tighten. IF you do not align the TPS rotor and tabs properly, you’ll have a check engine light later. Note in the pics that there is a little 3 sided slot in the TPS rotor, and it looks like this is where the tabs should fit. They do NOT fit here. They should go on the other side, which is flat.
Install TB on UIM and intall UIM on engine. Reconnect the intake air temp sensor under the UIM, the ISC motor plug and the TPS plug. IF the engine is in the car, connect the map sensor hose.
Here’s the turbo manifold with the flapper door, stock.

For full nonsequential, the flapper in the manifold must be removed, and the hole capped off. You can use an Oxyacetylene torch or a cut off wheel to remove the flapper. You can get the hole welded up, tap the hole for a plug, or just install a spare bolt and nut with a couple of washers to plug the hole (what I usually do).
Manifold and shield installed,


Here’s the stock twins. Remove the top oil lines, inside and outside water lines, and heat shield.

Remove vacuum hose, actuator, and C clamp for pre control actuator.
Cap 2 vacuum nipples left open. Remove remaining pill from wastegate actuator vacuum hose.
Separate front turbo from center housing
Remove C clamp and take the rod off of the arm.
Open the wastegate flapper. Wipe the surface of the flapper and the turbine housing clean.

With the flapper closed, spray LIGHTLY with an easily visible paint around the flapper. You do not want to spray so much that the paint runs between the flapper and housing. This will give you your outline for porting. You can also use a scribe to make your outline.

Port wastegate, often checking to see where you stand in relation to the outline. Use a die grinder with a selection of stones, and/or carbide bits if accessible. You don’t want to port TO the outline, but leave about 0.5mm between the outline and your porting, for a good seal. Once you get your outline pretty much done, go and make a backcut at an angle downward (toward where the air enters the turbine) to assist airflow in making the 90* turn from the turbine scroll into the wastegate.

Once you’re satisfied close the flapper, reinstall the wastegate rod and c clip.

Remove plate and gasket to expose the precontrol flapper.

Cut it out and plug the hole as you did with the manifold earlier. As an alternative, you can tack weld the flapper in the open position (with the plate installed) but I prefer to cut it out, which is sort of the whole point of removing the turbos in the first place.
Reinstall plate and gasket. Reinstall front turbo, lines and shield.
install turbos.
Install primary turbo elbow. IF you ran a hose from the oil filler neck and/or the oil injectors, plug them in here. IF not, cap the holes.
Separate Y pipe. Remove CRV and hoses.
Remove butterfly, then charge control actuator. Plug the hole with jb weld.
Cap off the rear large nipple that used to go to the CRV. You can use large rubber caps, or plug the hole with jb weld. Cap off both smaller nipples as well.
Cap both nipples on front Y pipe.
Reassemble Y pipe by lubing the o-ring and working them together in a circular motion. Install Y pipe on turbos. Be sure the hose to the BOV is tight on both ends to prevent a boost leak. The BOV hose gets plugged into the UIM nipple. IF running a boost gauge, it goes on the other nipple. If not, plug that nipple.
Install crossover pipe.

You should now have a solid 7psi boost from about 3800-4000 up. A straight exhaust might still see a bit of creep on top end. You can use an external boost controller to raise boost as desired. IF you want to try to get back around 10-12psi, you can do so by:

-reinstalling the pill in the wastegate actuator hose

-reinstall and plug in the wastegate solenoid on the UIM

-remove the cap from the wastegate actuator, and run a hose from it to the wastegate solenoid…either nipple. Leave the other nipple open.

The computer is now again controlling boost, using the solenoid to raise boost to at least 10. You are more likely to see creep this way, however.

Rotary Resurrection - Tech Section
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