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Discussion Starter · #21 ·
If you see her, wave. She's way into her CRX.
She freaking texts me every time she gets acknowledged :bounce:

I told her about this forum. Maybe she'll find this thread one day. She's a photographer... should be lots of great pics to come.
 

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Not to revive a dead thread but this is the best source of Y5 into a CRX I've found so far, particularly the wiring, which will be my most daunting task. Long story short: I'd like to eventually put a D16Y5 into my '89 CRX HF that currently has a D15Z1 ('92-95 VX). It runs fairly decent with the Z1 for the last decade or so but it was my first swap ever back in the day and the quirks show for it (I have tried for years to track down the culprit of a random studdering while crusing annoyance perceived to be a ground short or misplaced wire). If I ever do decide to change it, I'd like to start fresh with OBD2 wiring as you have done and the extra 23 hp wouldn't hurt while keeping the mpg comparable, plus Z1's are getting harder to come by without 200k+ miles. I know it's been awhile since this write up and I was wondering if those pin outs were ever completed or any new info is available since then. Frankly, if I knew I could perform the wiring to your standard I'd have already done the swap.

Thanks,
Mak
 

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Discussion Starter · #23 ·
I don't see the crime in reviving a dead thread. The car's still on the road, I'm still alive and active with Hondas. It's great to have an old thread appreciated.

Your problem doesn't sound like a wiring issue at all. The Z1 can be finnicky. The O2 sensors wear out without throwing a code sometimes. Sometimes they throw a code just for coasting downhill too long. Any little vacuum leak and the car bucks wildly. The EGR gets clogged up and is difficult to clean. Again, there's no code to warn you. Parts places sell you the wrong plugs.

All the wiring info resides in my notes. One of the problems with trying to post it is all the many variations in the EFs. Si, HF, DX are different, 88 and 89 are different than 90 and 91. It might be better to tell people how to find and verify the wires than it is to try and tell them exactly where the wires are.
 

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Discussion Starter · #24 ·
2017 update. I have had my own 88 CRX Si for a couple of years now, and have recently had the pleasure [sarcasm] of swapping intake manifolds. I was having problems with the throttle and IACV sticking and it made the car very annoying to drive. From every stop, I'd have to punch the throttle to break it loose. Absolutely embarrassing on a manual trans car. Then as I coasted to a stop, I'd have to punch and drop the throttle to get it to drop from a 1200 RPM idle to normal.

Cleaning and lubricating the throttle cable didn't help, nor did adjusting the slack, or sanding down the groove I found on the pedal assembly. Disassembling the throttle mechanism and cleaning the plate didn't help, although spraying WD40 on the rotating part inside alleviated the issue for about a day at a time. Cleaning the IACV didn't help.

The 88 manifold is a little different than 89 and above, and used a different IACV. Any later manifold could use the much more common IACV. I had tried another EF throttle body and found that it also stuck, so I wanted to use one from a newer generation. I had a y8 manifold handy, and I thought it would be a quick, trouble free install having had done an entire engine swap before. I was wrong. My notes in this thread didn't include hoses sizes etc since in that project I was starting basically from scratch. Multiple trips to the parts store were the encouragement I needed to document the differences and report them here.

D16Y8 Intake Manifold into a CRX
Whether swapping in a whole D16Y5 or D16Y8, or just swapping the Y8 manifold onto your existing engine, a number of issues arise. My main purpose in this update was to show another option for mounting the IAT instead of inserting it into the intake hose, and to cover the complete install in greater detail.


Here is another option for mounting the IAT. Get a 88-95 IAT that has the mounting bracket (like your stock IAT). Drill and thread holes into the side of the manifold and screw it down similar to pre EK manifolds. Any Honda/Acura IAT from this time period will work.

Tools and Supplies
1996-98 manual trans D16Y8 Intake manifold, throttle body, fuel rail
Reuse your OBD0 Injectors
Injector upper O-rings
Liquid Gasket ie Hondabond, Permatex Grey (to ensure the sensor is vacuum-tight)
Intake Manifold Gasket
Throttle Body Gasket
88-95 IAT Sensor
Sensor mounting screws x3 (2 for mounting and 1 to make a tap)
Dremel w/cut-off wheel (for making a tap)
Automatic Center Punch
7/16 drill bit (for sensor o-ring)
5/16 drill bit (for sensor probe)
11/64 drill bit (for threaded holes)
Hose Cutters or Razor Blade
Longer, smaller diameter FPR to Fuel Tank return hose
Longer charcoal canister vacuum hose
New PCV hoses
Vice Grips
T-Handle Screwdriver
10,12,17mm sockets, wrenches
7/8 Wrench (to remove fuel hose from old manifold)
Bent Needle Nose Pliers (to hold hose clamps)
Small Round Rasp


Start with the center hole for the probe. I chose this spot near the center of the tube, up off the lowest point, on a flat surface a little away from the casting line. There's lots of wiggle room here, just use your common sense.

Once that hole is drilled, insert the sensor and start the screw holes. Once you've made your marks with the drill bit, move the sensor and finish one of the holes. Re-insert the sensor with a screw in the hole, then finish the other hole. This is to ensure everything is perfectly aligned. Now remove the sensor again and deburr the holes with a round rasp and some rough sandpaper.

Now you'll need to create a small recess for the probe o-ring or else the sensor wont sit flush. I used a 7/16 drill bit on the center hole without trouble, but you may decide to drill this part first 1mm in and then drill the 5/16 hole for the probe after.

Tap the Screw Holes
To thread the holes, I prefer to make my own taps. Taps are expensive and it's difficult to determine and then find the proper size. Instead I'll just go to the junkyard and get a couple spare bolts from whatever it is I need to tap. So get at least four IAT mounting bolts- two to mount the sensor, one to make a tap, and one for backup.


Here you can see that I've made taps for thread chasing spark plug holes (with head removed), head bolts, two different sized suspension bolts, and the coolant gauge sensor. Keep in mind that these aren't only used on the exact part they came out of, but in any place on the car that uses the same thread pitch and diameter.



Clip the head of the bolt in some vice grips or table vice, then use a dremel to cut 3 or 4 grooves into the threads evenly spaced. It doesn't have to be precise as long as the threads aren't damaged.


Rinse the metal shavings out of the manifold with water and let dry. Then reassemble with your throttle body, fuel rail and now IAT Sensor.


That vacuum output on the bottom right needs to be capped off. I use a cap taken from a Honda Accord intake manifold.

Breather Box
This is a great opportunity to remove and flush out the breather box on the back of the block. There are only two 10mm bolts mounting it below the intake manifold. I soak it in diesel and then wash it out with warm water and dish soap.

Bypass coolant to the IACV
Since I live where it never drops below freezing, I bypassed the coolant going to the IACV. This simplifies the complexity of hoses a little bit and reduces heat soak to the manifold. The bottom plate on the IACV can be removed, although the two screws are prone to seizing. In that case I cut a gash across the screw heads and turn them out with a large flat blade screwdriver. If you don't want the trouble then the hoses on the underside of the throttle body can be removed and the lines left open. I prefer to run a hose from the engine's throttle body coolant output to the engine's IACV coolant input. This is more reliable and arguably cleaner looking than capping them off.


To make it look clean and stock, I grind the metal coolant line from the crankcase heater and just leave the vacuum output to the intake hose intact. On the right is an uncut breather heater, and beside it my finished line, painted black next to the remnants of the piece I cut from it.

I believe the coolant line is used to heat the crankcase gases passing through the tube to stop them from condensing. They're sucked back into the engine to be burned and then hopefully cleaned by the cat converter. Bypassing the coolant hoses here disables this functionality, but having them potentially leak and cause an overheat is an unacceptable risk.

Throttle Cable
The DX cable is ridiculous, cutting across the engine and back in a big loop. The CRX Si cable is too short. The y5/y8 cable is just barely long enough but is on the max end of the adjustment. This can be remedied by cutting down the rubber bump stop on the pedal side of the cable. Leave just a few mm to act as a washer around the nipple shaped end where they cable goes into the sheath.

On the left is the EK VTEC cable and on the right is the CRX Si, which you can see is much shorter. Note the rubber bump stops on the bottom of the cables.


Here I show the amount to remove from the EK cable to put it right in the center of the adjustment range on the bracket on top of the manifold.

Intake Tube
After the swap you'll need an intake tube to connect to your airbox. If you have an aftermarket intake, you're probably fine. I haven't tried it so I don't know whether the new throttle body position moves the intake far enough to cause an issue. For keeping it stock looking though, neither the CRX DX or Si tubes will work. The Si tube is too short and the DX tube is much too long. In this thread's original project, I cut down the airbox to fit the DX tube and it looked fine once installed. On this 2nd go around, I decided to try an EG intake tube and it fit without modification. It does cause a sharp bend in the flexible section of the tube, but this produces no noticeable effect on engine performance. I consider it a viable alternative because you can just slap it on and go.


The DX tube is too long, requiring you to cut the airbox lid as I did in the original project in this thread. The angle isn't quite perfect but it's acceptable.


CRX Si tubes are simply too short, as are 96-00 HX and EX tubes.


The EG tube is a perfect fit except that it causes a sharp bend in the flexible section of the tube.


Here is a closeup of the kink. It's not too bad in my opinion and the ease of fitment makes it my new preferred option.
 

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Hey just an update on this car you featured in the blog. Been running great! Two cross country trips and no issues. Only recently a CEL did come up. I'll try to get her plugged in soon and let you know what the status is, but it doesn't seem to be s major issue. Also, I will be in San Diego for a bit if you want to take a look at it and still in the area. :)b
 

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It was a fuel tank pressure sensor error that came up as the CEL Code! Hmmm...so right now I have some transmission fluid leaking, coolant leaking, and oil leaking (could just be around the oil pan). Should I save this car? How many miles were on the original 1998 engine that was installed? It still sounds good, runs good, but radiator hoses and thermostat plus new struts and shocks (just to get started) will be upwards of $1300...if I knew how many miles on the engine that was installed it would help a lot! Thanks!
 

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Have you heard anything back on this build? Was it worth it? Any news on the MPG or functionality? This thread is incredible by the way thank you so much for making it.
 

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Yes! So to clarify, the white CRX featured in this forum was converted by user "suspendedhatch" for a friend. Then, that friend sold the car to me.

I was on a snowboarding trip in Utah, trying to get home, and didn't realize I had been given a pretty good deal on this car, but as I've owned it and run into CRX people, now I know it was actually quite lucky. I was just looking for a Craigslist car to get me home from Utah to Michigan after my snowboarding trip.

Since then I have driven this car across the country several times, without any major issues. It averages around 40mpg!

The only problem I had recently is a fuel pressure sensor light made the CEL turn on, but there is no fuel pressure sensor installed, so it must just be some glitch in the conversion. I would like to get this addressed, but am not sure where to start. Other than that, I do worry about the flywheel being exposed as I drive through snow in the mountains, or desert terrain with lots of dust...

Next I hope to do a little restoration to the vehicle, and in that way do justice to the conversion suspendedhatch completed. I am looking at getting some good shocks and struts, not a race car suspension, but more of a rally suspension. I have have been impressed with how well this car does in the mountains, going up steep hills, getting me down some dirt roads with good clearance, so I like the idea of giving it a rally suspension so it can keep exploring with me.
 

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Yeah the work he put into making this car functional is incredible. I actually own a CRX HF and a Civic HX and was thinking of doing exactly what he did to your car. A perfect combo of weight and power with what sounds like almost no MPG loss. This is really the only thread I have found that discusses the process in such detail. It's so cool. Maybe I'll see this car sometime when I'm down in SLC.
 

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Discussion Starter · #31 ·
StormTrooperCRX said:
Yes! So to clarify, the white CRX featured in this forum was converted by user "suspendedhatch" for a friend. Then, that friend sold the car to me.
Hey! I told Jessica to turn you onto this thread. Glad to see you found your way here.

The fuel tank pressure CEL isn't a glitch. You need a 96-97 HX MT ECU. 37820-P2N-A21, A22, L21, or L22. In 1998+ emissions regulations required addition of a fuel tank pressure sensor inside the gas tank. Despite the CEL, it doesn't affect the way the engine runs, and that is why I felt okay leaving it.
It's a 5V sensor. The ECU expects to see 4.5V to 1.5V. When there's pressure in the tank, the ECU stores fuel vapor in the charcoal canister to use for starting and when the coolant temp is below operating temp. It accounts for about 3mpg.

As for the flywheel cover, a custom one will have to be made. It wouldn't be hard to get some sheet metal, put a couple folds and holes into it, but at the time I did this conversion I hadn't messed with fabricating sheet metal yet.

I would have done a lot more with this car, but it wasn't my money to spend. At one time I had found a clean white door in the junkyard but she turned it down. I was on the hunt for interior but again she couldn't justify the expense. I attempted to swap the seat rails onto some good seats but the 88 seat pans are closer to 87 than 89+, wholly different design.

If you are going to restore/upgrade the car, post up some pics! And if you ever decide to part with it, bring it to San Diego. Even though I have a 90 Si, I'd love to pick up where I left off. My email is my username at gmail. There's a link to my website in my signature.
 

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Hello all,

The information in this thread is great and I've been planning on doing this conversion for years. Now that I finally have the time, I was wondering if you could point me in the right direction. Here's my setup: 90 SI with a JDM ITR swap, using a P73 ECU. I have a complete dash and engine harness from 98 4dr CIVIC MT but I'm stuck at the GREEN connector (C131 22-pin from OBD2 ECU to the car).

Do you have a write up for that plug?

Thanks
 

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Discussion Starter · #34 ·
That plug is called C131. I just recently swapped an f23a into a Civic EK, and in the process I tore down an engine harness to physically trace every wire. The official documentation labels most every pin as "pgmpfi" which is unhelpful, and posts on other forums are vague and have inaccuracies.

I've been working on a F23 into EM swap guide that includes detailed info of C131. I would also like to do a guide for converting a CRX to OBD2. I have all the written notes from the swap in this thread and I just need to find time.
My Patreon is patreon.com/boy**** That is where I post all the guides and templates as I create them.
 

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Hey its 2021!

I'm doing a similar swap y8 with the stock ecu and crx engine harness on a 91 dx.

Someone correct me if I'm wrong but I believe there is a jumper for this made by HA motor sports

https://www.hamotorsports.com/products/ ... obd2a-harn

I'm planning on getting one as soon as they come back in stock.

As the original post states there is very little information on this. Great write up, it has shed a lot of light on my project.
 

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Discussion Starter · #36 ·
Hey its 2021!

I'm doing a similar swap y8 with the stock ecu and crx engine harness on a 91 dx.

Someone correct me if I'm wrong but I believe there is a jumper for this made by HA motor sports

https://www.hamotorsports.com/products/ ... obd2a-harn

I'm planning on getting one as soon as they come back in stock.

As the original post states there is very little information on this. Great write up, it has shed a lot of light on my project.
How did your swap turn out?
 

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Well it's 2022 and this thread still going.

I would like to do the same thing but I'm a bit confused.
This is what I understand in a nutshell. Please correct me of any mistakes or missing info.

Once engine is installed( my case Y8 no egr)

1.Get matching engine's year ecu + wiring harness( engine to ecu).

2.Get dashboard wiring(green plug) as well. To use it for all non sensors related accesories, like ac, eld, clusters indicators and lights...etc
More wires will be using an additional connector plug by drivers side side wiring.

I'm keeping old transm. So no work there.
I can weld an extra O2 bung for the down stream sensor.
Possible mismatch of water outlet for upper rad. Hose.
I'm not adding the fuel tank sensor either.
Mine is dpfi, do I still have to undo the blue taped wires. Wouldn't the new ecu harness connect to main relay overriding this.

Car is a base model or Dx. Ant it's being sitting inside the garage for over 6 years, age is starting to catch up with me so I hope I can do this as soon as possible.

Any help is greatly appreciated.
 
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