Tag Archive 'CRX'

Jul 30 2008

CRX D15Z1 (Civic VX) Fuel Economy Swap Guide

Since I knew what a Civic VX and d15z1 was I’ve always wanted to toss one of the swaps in my car. I never really had any money and was trying to look out for some sort of local deal, but in the end I’d saved up some money and figured I’d just go for a JDM swap. It’d come with all the sensors and wire harness and a bunch of junk I figured I’d end up spending for anyway, so I went ahead on bought the damn thing from a Canadian importer for $520 USD, shipping included.

Thing came in about 3 days (all the way across the continent and to my door), and I was ready to get started. I knew all the basics and honestly didn’t even look at anything online before starting the swap. Just figured I’d go ahead and do it and see what came up. Anyway, I intend this page to be a guide for those looking at the swap that can already do stuff like undo bolts and then put them back where they came from. This was my first engine swap, and it went fine, so I’m not going to bother with how to swap the engine as much as I’m going to discuss the specifics of this swap.

Why did I do it?

The short of it is that I wanted better fuel economy, and I knew this was going to be the most efficient engine I could get. The d15z1 has both vtec-e and lean burn, and is smashing good with my HF transmission.

Also, as you can see from this image, my gas mileage has sucked recently due to a doomed CX head swap. It was really sucking, and the car had horrible power to booth. Nowadays, I’m up in the 60s, with hoop dreams of fuel economy up in the 70s. Right now I’m just sitting on the 3rd tank, and I’m hoping to keep it up above 60 mpg consistently, though the numbers seem a little wonky just halfway through this tank…but that’s not important.

Anyway, the d15z1 swap was pretty cheap, maintained stock power, and promised much better fuel economy, so I went for it. I would’ve gone for an even smaller engine if I could get one, but it’s not exactly easy to find a working insight swap just laying around.

What did I have done beforehand?

Previous DPFI -> MPFI and and OBD0 -> OBD1 swaps left me in a decent position to get this done without having to rewire everything myself.

I did the obd1 rewiring myself, but in hindsight, having bought a conversion harness probably would’ve been a good idea. It’s not that it was hard to just chop my old plugs off, but it’s kind of messy now.

Also, when I did the dizzy swap I went with obd0 plugs since I got a dizzy with no plugs, and even though rewiring the dizzy was really easy, i would’ve saved 30 minutes if I’d thought ahead and used the obd1 plugs from the git go.

So, moral of this story (and more things you’ll learn later): think ahead!

What didn’t I have done beforehand (or what should you know)?

The fuel line on the VX is weird. You can see it in the picture, but it’s got to run around the EGR, neither my stock DX nor the replacement CX fuel line I’d been running would fit properly for the new, egr enabled engine.

I spliced to lines together to get it up and running at first, but I ended up spending 80 bucks for the damn thing from majestic honda, so try and find one in advance, but be warned that they’re hard to find.

The EGR Control Box is really just a bunch of crap, and is kind of hard to find. Since it’s on the firewall of the car it won’t come with the engine, and there aren’t many running around. Try to get one from someone who has swapped out a vx engine, I ended up spending 50 bucks on one cuz I needed it fast. Here’s what it looks like and the parts diagram:

ECU pins are a pain, and you’re going to need more for the VX swap. I only needed a few, but I bought some VX plugs anyway for about 10 bucks shipped. I had to wait a few days to finish my ecu wiring, so I’d wish I’d done it in advance.

The driver side engine mount that connects to the block is different from the EG civics to the EF civics, so you’ll need to swap it out. I forgot to do it until the engine was in there, and then I couldn’t get the crank pulley bolt off (easy solution, drove to my old shop and did it there), but you’ll need to remember that and know that you’ll need to notch the timing belt cover a bit for the new (old) mount. It’s hard to see in the picture, but you’ll see what I mean when you do it yourself.

Don’t forget how annoying the shift linkage pin can be. To tell you the truth, I just dropped the linkage with the engine and didn’t mess with the pin. After my last experiences with that, I figured this way was easier.

Don’t forget to be prepared to buy a new o2 sensor. They break easily. I got mine here and had good luck without paying 3-400 from honda (wasn’t cheap though).

JDM Engine Note: As you can see, the JDM catalytic converter has a second o2 sensor on it down near the bottom. You don’t need to worry about that but to leave it in or plug it so you’re not leaking exhaust.

Anyway, on to the swap!

So, how do I stick a d15z1 in my CRX?

Don’t forget this, first of all:

Pulling the engine

It’s seemingly simple! Just don’t let me forget anything! (NOTE: I’m not going to number the steps, that seems a little too arbitrary since I don’t plan on making them uniform difficulty or importance).

Safety, as always, is a priority. If you’re going to be doing this kind of work, make sure you have a proper jack, proper stands, and know where to jack up the car safely.

Anyway, the first step to anything like this is to disconnect your battery. With that out of the way, I just started stripping stuff off. Intake, wires, all sorts of stuff. I just disconnected everything I could besides the mounts.

Once I had a bunch of random junk off, I drained all the fluids and removed the coolant hoses from the engine.

I decided to remove the A/C at the same time I did the swap (I know, I know, it was leaking anyway and I just didn’t care), so I had to pull that out. Normally you’d need to empty the system, so you’d have to take it to a shop and have them do it. Shouldn’t cost too much, really. The a/c hoses normally require some big wrenches, but since I don’t own them I just used two vice grips and the came apart fine.

After pulling the a/c compressor and the hoses, I realized I needed to get rid of the stuff in the bumper and in front of the radiator. I pulled the bumper and removed everything off the front (with the intention of sliding the engine under, anyway), and pulled both the radiator and the a/c junk. Under the dash there is a clamp and some bolts, which allows you to pull out the a/c stuff, remove it from the case, and toss the case back in.

On the radiator I got rid of the stuff you see in red. The one fan is for the a/c and the hoses are a/c or automatic transmission related.

Next up is the axles. Took off the shock forks and then I undid the lca using the stick-a-1/2″-pry-bar-between-the-lca-and-the-knuckle-while-lifting-the-knuckle-then-lowering-it-down-and-jumping-on-the-studs-until-it-popped-method. I’ve always done it this way, and there may be a better way, but I like this. From there I just pulled back the axles and hoped they wouldn’t get in the way.

So, by this time you should have everything nominal removed besides the mounts, however, life will be easier if you remove the alternator and a/c compressor. It’ll prolly be easier without the intake or exhaust manifolds as well. Before I removed the engine I pretty much had it stripped down to a long block.

No, for the actual removal I had everything off the front of the car I could get off, including the front crossmember. Before actually dropping the engine, I lowered the car as close as I could to the ground the slipped a jack under there. I removed the transmission mount first, gave it some support with the jack, did the driveside mount, and lowered the engine completely. I did this alone and it wasn’t too hard, so *shrug*

Then I jacked the car up as high as I could and slipped the engine out under the front of the car.

Sticking the new engine back in

Hopefully I didn’t forget anything about pulling the engine, because we’re about to put the new engine back in.

The first thing to figure out is how you’re going to move the engine around. This image is not a joke, it worked for me:

There’s not much I can say here but do everything in reverse. I put the new engine in with all the manifolds and alternator on, so it was a bit tighter of a fit. Either way, be sure to put the driver side mount on the engine first and cut the timing belt cover to fit.

Once the engine is in, before you start hooking stuff up, make sure to put new fluids in the engine and the transmission, don’t want to forget that. From there I hooked up the cooling system and left off the radiator cap so I wouldn’t forget that either.

Anyway, after all the basic stuff is done, you start to get into a few annoying things. On the back of the DX block was the coolant temp sensor, in the shape of two single male/female prong plugs. I had to chop them off and solder on the z1 plug so that I could hook it up on the thermostat. I’m told the sensor isn’t polar, so it doesn’t matter how you solder up the plugs.

Also, on the back of the JDM intake manifold there is no spot for the purge solenoid, so you need to tap into some manifold vacuum and put that in and tie wrap it to something.

Hopefully you have the distributor wired up, but if not, follow these diagrams to switch around your wiring to get on the obd1 vtec distributor. Similarly, if you don’t have obd0 to obd1 ecu wiring then you’re gonna need to figure that out. I can’t give you much help there, but either buy a harness or just chop plugs and wire. Here are some pinouts, have fun.

Here’s where it gets to start customized. You’ll need to follow this to wire up your o2 sensor. I ran both the power and the ground straight back to the ecu just to be sure. I’ll talk about troubleshooting the o2 sensor here in a bit. The o2 sensor plug has 7 wires, and looks exactly like an obd1 distributor plug, in case you’re trying to find it.

The next thing you need to do is wire up stuff like the egr, egr control solenoid, vtec pressure switch, and vtec pressure sensor. That’s pretty damn easy, just follow these diagrams.

Other than that and the purge control solenoid, I don’t know what else is custom about this swap. Just make sure everything is together, all your fluids are in, and you don’t have wires flailing around. Go ahead and start it up! You should be done.

If not, I’ll have some o2 sensor troubleshooting (code 41).

O2 sensor troubleshooting

The internet way to fix such an issue is to check your wiring until you’re confounding about the solution and then to buy a new sensor. The real way is to follow these instructions I’ve taken from the 92-95 civic manual. You’ll need a digital multimeter, but it’s well worth it, I should say.


Well, my engine swap is done and good and hopefully yours will be done as well. I think this chart speaks for itself (7-18-08 being the first fill after the swap):

The first spike into the 50s you see is after my auto to manual swap, the following dip is after my misguided head swap, and the current spike into the 60s is the d15z1 goodness at work. If you’ve done or plan on doing this swap, drop a comment.

Also, if you have any questions or things I left out, just leave it in the comments and I’ll fix it up.

21 responses so far

Jul 11 2008

1988-1991 Honda Civic/CRX D Series Gear Ratios

Published by Benjamin Jones under Tech Info

Civic STD
Civic/CRX Si
Clutch Type
Trans. Code
Final Drive
2.95/3.25 (CA)

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Jul 10 2008

DIY CRX LED Dome Light

The power in your car is not free, it comes from the alternator and is a product of the huge amount of drag that this electrical generator puts on your car’s engine. I chose to begin my (unfinished) quest for LED lighting by converting my dome light to LEDs. It make be a modest start but it looks great and I’ve recieved many comments on it, even from some outside of the car enthusiast world. It seems much harder than it is, so don’t be intimidated if you’ve never done anything of the sort before.

Purpose: To cut down electrical loads on the charging system.

Time: 1 hour

- Soldering Iron
- Knife

- LEDs (I used 15 10,000 MCD ultra brights)
- Resistors (100 ohm for this project)
- Some perf board (4 bucks at radio shack)

This is my awful demonstration of how the circuit should go. The resistor is crucial! I blew up one of these LEDs once and a flying chunk but a nick in my living room wall.

Grab your dome light outta the car. Mine was already out for randomness’s sake. Make yourself a little drawing to see how big the perf board should be cut.

Smash it into shape.

Start sticking the LEDs in. You want to line things up so that you’ll be able to tie all the negative sides together to go to the ground and the positives together in bunches of three so that each three can go to a resistor.

Look at it and be like, that’s hella sloppy. I just tied the four on the one end together and called it a day, in the end I soldered that straight onto the lead in the dome light housing.

All in!

Soldered completely.

Test wiring, notice the resistors are in also, don’t forget these!

All done but not mounted!

Mounted up on the car. I had to cut the board a bit to get the screw in there. Night pictures ought to be done but you can’t really see anything, just trust me and get it done! You can also use amber LEDs if you are into that look.

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Jul 09 2008

CRX Radio Antenna Removal

Have you ever hated the look of your radio antenna? Or maybe been bothered by all the aerodynamic drag? I have. Solution: It’s gone!

Purpose: To cut down on aerodynamic drag and improve the look of the car.

Time: 15 minutes

- Flathead Screwdriver

- Block Off Plate
- Gasket
- Reused Screws

You can get this stuff at the local dealership or online (cheaper) at one of these places.

Here’s the antenna. Undo the two screws and yank it out. Make sure to unplug the other end from the stereo.

Awful picture of the antenna on the ground:

The left over hole:

The two parts, I spent about 10 bucks on both:

Put them on with the old screws:

Admire your work:

The CRX no longer looks like an RC car! Quick and easy (mehbe not too important) but it was certainly worth it to me.

3 responses so far

Jul 09 2008

DIY Front Grill Block

The front grill block is on of the quickest, easiest, and cheapest ways to cut down on aerodynamic drag in your vehicle. While it doesn’t amount to much, it does make a difference, especially considering that a large amount of aerodynamic drag is caused by this opening. It’s best to leave it only partially blocked so that the radiator recieves some airflow, however, a large block is okay because radiators are typically larger than they need to be, and fuel economy drivers tend not to abuse their engines too heavily.

Many new cars, including certain Mercedes and Hondas use electronically controlled radiator shields that open/close depends on engine cooling requirements. Take a look at this Civic for an idea what this looks like:

Purpose: To prevent air from entering the grill to reduce drag as it moves through the radiator and engine bay.

Time: 1-3 hours depending on complexity of project

- Hobby Knife
- Hot Glue Gun

- Coroplast
- Spray Paint
- Foam (for modeling)

I chose to repaint the trim on my bumper as well as do the grill block at the same time, so first I removed the bumper. If you leave it on you can get it done much more quickly, but that’s up to you. Just follow my mounting instructions with the bumper on the car.
Click here to see how to remove your bumper (as shown in the wire tuck page).
This is my bumper removed, you can see the grill opening as well as the two pockets on the side. The side pockets are not supposed to cause much drag but I covered them anyway just to smooth thing out as much as possible:

Here’s another shot to get an idea of the bumper’s geography:
I used this style of insulation foam to make templates because it is easy to work with:
One of the templates sitting in a side pocket:
I then transfered the template to the coroplast, cut some support to place down the side of the pocket to mount the coroplast to, and cut off part of the coroplast towards the center of the bumper so it would mount flush to the bumper where it tapers together:
The center pieces are just glued to the ribbing on the grill and then glued around the edges from behind:
I taped up all the painted portions of the bumper so I could respray the trim and the coroplast black:
A shot of the finished product remounted:

I think it turned out pretty darn good, :-)

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Jul 09 2008

DIY Honda CRX Wire Tuck

Published by Benjamin Jones under Cosmetic,Wiring

One of the things many car owners dream of is a cleaner, more simple engine bay. It seems like an impossible task; what does one do with all that stuff? There are a few solutions that are simpler than you may imagine. I begin working on this task in the form of a wire tuck and hope to give some guidance as others go through this process. At the same time other things will be tucked or cleaned up, but the main objective at the moment is wiring.

Purpose: To be honest, there is no purpose to this beyond cosmetics. Some make the argument that you are better able to service your wiring when it is where you want it, but I’m not sold on this. I do, however, know that I am much more familiar with my car’s wiring and wiring itself. It was well worth the effort.

Time: Yikes! It depends on how much you do, and how thoroughly you do it. It took me a few days while being patient and thorough (not entirely full days either).

- Automatic Wire Strippers
- Soldering Pen
- Lighter (to shrink the shrink wrap)


- 200 foot of stranded wire, various sizes. Just take a look at some of the wires and you’ll get an idea what you need
- Solder, I’ve had a pound spool I’ve used over and over again
- Shrink wrap, various sizes but mainly 12-20 ga.
- Electrical tape

Before shot, it’s hideous:
1991 CRX Before Wire Tuck
Diagrams of the two round shock mount plugs, make sure to label the identically colored wires!
DIY Wire Tuck
DIY Wire Tuck
DIY Wire Tuck
DIY Wire Tuck
This is what headlight wiring looks like, one of the main tasks will be to relocate these wires to the fender brace so they will be out of the way:
DIY Wire Tuck
Now we’ll begin with taking the body panels off so we can relocate the wiring.
Take your corner light out:

T-bar comes out to help remove the bumper, it has 4 10mm bolts up top, on on the bottom, and the hood pop cable is clipped to it:
1991 CRX Before Wire Tuck
Those little screws were rusted in badly so I had to take them out with the vice grips:
1991 CRX Before Wire Tuck
Also on the bumper there are two 10mm bolts on the bottom and two screws on each side in the wheel well. Also, there are two screws under the corner light. Once that’s all off slide the bumper off:
1991 CRX Before Wire Tuck
The headlight wiring will be tucked down through the support brace for the fender. To get the fender off there are 3 10mm bolts on the top, two in the front corner, two under the door/drim area at the bottom and one on the top behind the door. Get at these with a wrench from the side with the door open so you don’t damage your paint. You’ll also need to detach the wheel well plastic from the body of the car, just undo the plastic screws or slide the plastic around them.

I lost the picture, sorry!
Unplug everything. You’ll need to take off the horn to get the plug off, but it’s only one 12mm bolt:
1991 CRX Before Wire Tuck
Yank the headlight harness out the side there so you’ve got it all acessible:
1991 CRX Before Wire Tuck
Oh no, look at those plugs. Two go to the windsheild washer nozzles. I took out the reservoir and the lines, but if you wanted to you could leave the reservior (or move/modify it) and tuck the lines in the fender brace. At this point you basically just cut the plugs off, label all the wires (as you cut them off), and pull the wiring inside the cabin so you can put it out the side:
1991 CRX Before Wire Tuck
Side of the car where the tucked headlight wiring will come out and go into the fender brace:
1991 CRX Before Wire Tuck
Cut open the harness so you can start cutting plugs and labeling the ground wires. The annoying thing here is that some wires go into the cabin and some go to the multiground. I just cut the cabin wires and tucked one at a time while labeling the wiring on the multiground:
1991 CRX Before Wire Tuck
Pull this little plug out. Through the hole the wiring will come out of the cabin of the car. When you cut a wire you pull it through from under the dash and shove it out the side here:
1991 CRX Before Wire Tuck
The hole it comes out of in the middle and where it goes in the very top-right:
1991 CRX Before Wire Tuck
Opened harness from the engine bay, all these wires will be gone besides the two to the master cylinder:
1991 CRX Before Wire Tuck
The harness from the inside:
1991 CRX Before Wire Tuck
Cut the first plug, pull the wire through, shove it out, and realize you’ve started:
1991 CRX Before Wire Tuck
First wire is wrapped around and through the fender brace:
1991 CRX Before Wire Tuck
Comes out through this little hole here:
1991 CRX Before Wire Tuck
There’s a multiground for each side, make sure to label the wires just because. Iono if it matters but labeling is very important just in case!
1991 CRX Before Wire Tuck
Everything cut off the multiground and labeled up:
1991 CRX Before Wire Tuck
The multiground tucked into the corner bumper/fender area:
1991 CRX Before Wire Tuck
Look at all the wires coming together:
1991 CRX Before Wire Tuck
Crappy shot of all the individual plug wires taped together:
1991 CRX Before Wire Tuck
All the wires on the passenger side that go through the fender. The black wires are all for the wiper motor:
1991 CRX Before Wire Tuck
You can see where the wiper wiring goes into the fender now:
1991 CRX Before Wire Tuck
Cut open the wiring for the injectors and run it up from the bottom under the IM runners:
1991 CRX Before Wire Tuck
Turned the brake booster vacuum hose around to take advantage of its natural bends and cut some off on the unbent side. Don’t forget to flip the one-way valve if you do it like I did:
1991 CRX Before Wire Tuck
Better look at the driverside wiring all done up:
1991 CRX Before Wire Tuck
Almost every wire going in through the old VSS cable hole, damn it was getting cramped after a while, this was really a pain, but worth it I think:
1991 CRX Before Wire Tuck
The two MC wires going through that driver side firewall opening:
1991 CRX Before Wire Tuck
Passenger side multiground and relay down where the intake resonator used to be:
1991 CRX Before Wire Tuck

Fusebox: Really no pictures needed, everything screws off/unplugs besides the power wire to the battery, which you need to lengthen X amount depending on where your battery is and how you’re routing the wire. This was the easiest part, by far.

Finished product:

1991 CRX Before Wire Tuck
1991 CRX Before Wire Tuck
1991 CRX Before Wire Tuck

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