b18a1 swap
Posted by Mad Scientist on December 14, 2007
Some of you may have followed my thread on SHO here regarding the long and laborious swap that was supposed to be the “easy” b-series swap. Since hindsight is 20/20, I’m going to offer this post as a writeup to prevent others from running into the same problems I did. You’re all big kids, I’m sure you can come up with your own original problems on your own. No need to repeat mine.
Here are my personal recommendations to anybody planning to go from this:
to this:
in their CRX.
Step 1: update to a 1990-1991 CRX Si
Step 2: Get your parts
- b18a1 engine (obd0) from a 1990-1991 Acura Integra
- cable b-series manual transmission
- (obd0) pr4 or pm6 manual ecu
- Modified Shift Linkage
- Integra shift linkage is too long, it can be cut and welded
- Hasport Shift Linkage
- Radiator - the Integra radiator has larger Interior Diameter hoses, so CRX hoses won’t fit out of the box
- Integra radiator with shortened Integra hoses
- CRX radiator with Integra hoses and a chunk of CRX radiator hose stuffed in the end
- exhaust header
- top half: Integra
- bottom half: CRX Si
- 1990-1991 Acura Integra axles
- (these are ABS-sensitive, so if your CRX doesn’t have ABS you’ll want non-ABS axles)
- 1990-1991 Acura Integra throttle and clutch cable
- Motor mount kit
- CRX Si Engine Wiring Harness
- Integra Oil Filter
- Integra Fuel filter
- Any Belts/Hoses that are cracked
- 1 can of Spraypaint or clearcoat (if possible, match with your engine bay color)
- Oil for Transmission and Engine
- Fresh Radiator Fluid
- Sharpie™ Marker
Step 3: Get the basic tools, if you have air tools, substitute them where applicable
- Engine Hoist
- 10mm, 12mm, 14mm, 17mm, 32mm(axle nuts) wrenches (gear wrenches and a ratchet will save you a lot of swearing)
- 4 Jackstands, not just 2
- Fluid Containers
- Radiator Fluid
- Oil
- Burly Jack
- Hammer(s)
- Shop Light
- Plier set (for hose clamps and such)
- Big old assorted pack of zip ties
Step 4: Roll up your sleeves
- Remove Hood
- Remove Intake
- Remove Battery
- Drain Fluids
- Remove Radiator
- Remove Axles
- Disconnect Clutch Cable from transmission, remove from car
- Disconnect Shift Linkage
- Bitch Pin
- Disconnect Exhaust Manifold from Catalytic Converter
- Disconnect Fuel Lines
- Disconnect Throttle Cable from throttle body, remove from car
- Disconnect Vacuum Lines
- Disconnect Ground and Positive from the engine bay fuse box
- Disconnect ALL wiring harness clips, put engine wiring harness clips on top of the engine
- Bolt up Engine Hoist
- Unbolt Transmission and Motor Mounts
- Pull that old, tired Engine and Transmission in one big greasy pile
Step 5: Now that your sleeves are rolled up, it’s time to get some REAL work done.
- Get a bigger hammer
- Fit the engine in so all 3 motor mounts are lined up (you won’t need that pesky front motor mount any more)
- Using your sharpie, mark off the spot next to the timing belt that is now rubbing
- Pull the motor back OUT
- Whack the rub-spot of the engine bay with the hammer until you believe it’ll be out of the way.
- Sand down that spot, and spray some primer/sealer/spraypaint on it to keep it from rusting
- Lower the engine into the 3 motor mounts, and tighten them down
- Once that’s in snugly, remove the wiring harness from the d16a6 engine and bolt in all the wiring clips to the b18a1
- Some of these clips will be less friendly than others, and will require you to cut the grommet around them.
- Some of the clips are not used at all, such as the A/C compressor switch or the Power Steering switch.
- Some of these clips will be less friendly than others, and will require you to cut the grommet around them.
- Next, you’ll want to plug up the Power Steering oil lines in the transmission. It’s difficult to see in this picture, but they’re on the speed sensor of the transmission, under the distributor (fair warning, they aren’t quite easy to get to). I simply bought some fuel line (8mm if I remember correctly) cut a section short enough that it could loop without incident, and connected the two oil bungs:
- Now that you’ve got the fancy wiring out of the way, you get to play with the vac lines. The b18a1 is one of the most overcomplicated intake manifolds available. Whether you use the CRX Si MAP sensor or the Integra MAP sensor, you’re going to end up plugging the same vac spaces and running with a bare minimum of hoses in the engine bay. Unfortunately, I haven’t drawn up my vac diagram yet. I’ll get to it, I promise.
- Hook up the ECU to the chassis wiring harness.
- Check all your grounds, make sure all wires are hooked up (if I’ve missed anything, be sure to leave a comment)
- Connect the battery, position the “shifter” into neutral, and start the car.
Step 6: enjoy (please note, this is subject to the user’s discretion. My definition, for example, is continuing to troubleshoot little issues that crop up over time and small mistakes that could easily have been avoided by using a bit more foresight and planning during these stages of the swap)
January 17, 2008 at 4:14 am
First off, I would like to say props on your previous posts on SHO. I was hoping that you would be able to answer a few questions for me…I currently have an 89 CRX SI with a B18A1 swapped into it, (this swap was started by a friend and finished by myself around a few years ago so I’m trying to refresh/learn a few things) well this shell has seen better days (rust holes in floor, frame, body), and I currently found a 90 DX in almost immaculate condition that I am currently in the process of swapping. Although, I have to came upon a few discrepancies within different web pages that I must clear up in order to continue with the swap. The first one is regarding a dpfi to mpfi swap; I have read in some write-ups and on some boards that I can simply switch the wiring harnesses (engine and chassis [SI to DX]), others have said that the swap must be completed and that the harnesses cannot be used. The second discrepancy is actually in reference to your previous posts on SHO (sub-frame), when I had purchased the SI, the engine was already in it but needed wired, hosed, and bolted down. I had noticed when pulling it that the sub-frame had writing on it (some junkyards mark their parts with a combination of letters and numbers [which made me question if he had swapped the sub-frame?]), will this sub-frame from the SI have to be switched to the DX? (I have previously lost connection with the friend who started the original swap). Any input on these two discrepencies would be appreciated. I am sorry if this was posted on the wrong place, but I am new to this type of blog.
January 17, 2008 at 3:10 pm
All you have to do is do the DPFI to MPFI conversion, then drop the motor in as described here. The subframe does not matter. You won’t be using the front motor mount at all, so you could weld in a piece of steel and it wouldn’t matter as far as the engine’s concerned.
Honda marked parts with chalk/ink from the factory as well.
February 9, 2008 at 11:30 pm
There are some other b-series swap howtos available as well:
http://www.b16honda.com/b16swap.htm
http://www.norcalcrx.org/droppedcrxsi/step-by-step.htm
http://www.norcalcrx.org/droppedcrxsi/b18c-step-by-step.htm
http://www.norcalcrx.org/droppedcrxsi/k20-how-to.htm
You might want to check out:
http://hondaswap.com/hybrid-ed-ef-da/all-swap-info-ef-50719/
as well.
March 3, 2008 at 12:48 pm
hey bro awesome write-up…i just have 2 questions..when are you going to do the vacuum diagram???and did you do anything to the front mount??my motor will not go in properly
March 3, 2008 at 5:50 pm
As far as the front motor mount goes, I whacked on it until it was bent enough to fit the motor in, then eventually sawed off the mounting bracket. There are a few b-series kits that include a front motor mount, but as long as the bushings are polyurethane (if you can’t bend the rubbery stuff much, it’s polyurethane) you won’t need that front mount at all. Make sure you have the rear and both sides securely attached before you start up the motor though!
As far as the vacuum diagram, I actually took some pictures! Start here GALLERY and browse left or right.
Basically, with the CRX Si MAP sensor (pictured) you’ll need to run the bottom MAP line to the back of the intake manifold, and cap the other manifold bung (there are two, one right above the other, on the firewall side). Then you run one from the top of the throttle body to the side of the MAP sensor, and one more from the MAP sensor to the charcoal filter. Leave the larger vac lines in tact, since they don’t even interface with the computer in the first place (they’re just from intake manifold to head) and cap everything else.
That will get you out of limp mode. As far as getting 100% correct vacuum to the correct MAP sensors, I’m not entirely sure how that would work. It gets a little more complex, and goes beyond my rudimentary understanding of how a MAP sensor works. I don’t have the math to back it up. As soon as my drawing tablet comes in, I’ll draw up a proper diagram, but until then ask any other questions you have or point out any flaws in my explanation.
Good luck, and take lots of pictures!
March 4, 2008 at 6:22 am
on my b18a1 non vtec i have three sensors ! One is a thermol sensor.(green plug) One is a oil sensor.(one prong) And one is a temp sensor. (two prong). what did u do for the green plug. On the axels did you have to remove the outer dust seal on the axel itself. I know on the hub u have to remove the dust ring. i went to tighten the hub nut and the axel isnt turning freely The artical said something about none abs what b series has a none abs axel. Do you or any one have a pin out diagram for a 90 teg gs. I know i sak alot of ? but its the unknown that gets u in the end. thanks memphis
March 4, 2008 at 3:05 pm
You can get 90-93 Integra axles that are non-abs. That’s what most swappers get, and rebuilt half-shafts are easy to come by (and therefore cheap).
As far as the three sensors, is this what you mean? http://picasaweb.google.com/drummingpariah/CRX/photo#5104995500953293618
Do you have any pictures that you can offer to help explain exactly which one you mean?
April 3, 2008 at 9:28 am
ok so i went to do my vaccum lines and got really confused there arelike 4-5 metal linesright on the back of the I.M..and my sensors on the firewall are a little diff than yours,,could you send a vaccum diagram to my thread on HS..the one called ls already covered?
April 5, 2008 at 12:19 pm
One quick question, there is a pin (not sure if it’s a dowel pin or if it’s threaded) in the transmission holding the shifting rod to the transmission. I tried googling/searching for it on SHO, but I didn’t know the correct term for it and I just got a bunch of junk answers…Well my engine would be out and the B18 on it’s way in if I could get this one little f*cking pin out. I have been going to war with this little bastard all morning/afternoon and it’s pissing me off. I have been tying to get it out with needle-nosed vice grips but to no avail. Is this a dowel pin or is it threaded and any ideas on how to get it out? I would like to get it out because as soon as it’s out, my engine will follow (need to get the pin out then I can unbolt my mounts and jerk the son of a bitch right out). Thanks for all of your help guys…
April 5, 2008 at 12:22 pm
Head on ova heya:
Bitch Pin
April 9, 2008 at 1:11 am
one quick question cause u get asked a lot of them but i have a 1990 crx si with a b18a1 swap. my question is what color wires are the temp sensor for the computer on the head and not the sensor for the temp guage. i cant find a diagram anywhere. what color wires are yours. the reason i ask is because the dumbass that wired up the car didnt wire it up right so im throwing a cel 6 for a engine temp sensor failure or wire problem so i replaced the sensor and tried to reset the sensor and as soon as i go to start it the cel sets off the same code so something is wrong with the two wires on the sensor. i just need to know what color the two wires are cause my car will start after 15 minutes of turning it over and once it starts i have to rev it to 4000 grand to keep it running until it warms up a lil then it runs like a champ. but since the ecu is sensing that the temp sensor isnt working it cant give it the correct fuel adjustment for a cold start and thats when it doesnt wanna start when its colder than 45-50 degrees. if you have any help i would be so happy cause im out of ideas at the moment.
April 9, 2008 at 8:15 am
This is something I can’t especially help with. I’m very color blind, so I can’t go by colors. However, I’ll email a complete (really, very very complete) diagram of the wiring system to you.
April 12, 2008 at 9:14 am
I have done searching, but either I am a dumb ass and not using the right terms, or there isn’t anything (which is highly unlikely), but the fact still remains that I can’t find what I need. So here it goes…
I have a quick question…I have done the MPFI-DPFI swap on the engine side because I am using the CRX/Integra wiring setup (it was already done by my buddy and works great)…Well, I had finished the MPFI swap on my 1988 (donor) Rex at the ecu. I have recently ran into a problem with the wiring in me 1990 CRX though. The wires are different colors (but at the same pin location)on the ecu harness than the ones on the 1988 harness. My question is are the wires running the same components (I would think that they are seeing as how both cars are DX’s and the ecu pins would be in the same location)? Also would you be able to email me the wiring diagram in your above post also…
April 14, 2008 at 11:22 am
@Jordan,
Sorry it took me so long to get back to you, it’s been a busy weekend. I shot the manuals over to you, take a good look over them and come on back if you have more questions.
April 14, 2008 at 6:00 pm
hey bro thankx for the info but like most im still a lil slow on this thats why i want to do my swap. i got 91civic dx and i got the 91teg engien trany tha whole deal just got a problem wit the wiring,ecu my plugs dont match i also got tha complet 91si engien and i see that the si and the teg plugs match Help me out
April 14, 2008 at 6:24 pm
@Dream Sport,
With the DX wiring harness, you need to convert your wiring harness to MPFI before plugging the motor in, and you’ll basically scrap the b18a1 (Integra) and d16a6 (CRX Si) wiring harnesses.
April 15, 2008 at 7:02 pm
kool but how do i convert the wiring harness to MPFI? can u school me on that and what a bout the ECU do i need a conector or something like that and if i do which one?
April 17, 2008 at 12:11 pm
I googled it, and found a couple links you might want to read:
hondaswap DPFI -> MPFI
dx -> si wiring
one more write-up
I may be doing this swap myself in the near future, so I’ll be sure to write it up and take some pictures for you.
April 17, 2008 at 4:12 pm
kool ill be comin back to check it out thanks!
April 30, 2008 at 11:20 am
you ever figure out the vaccum lines??im still trying to figure them out myself lol
April 30, 2008 at 12:25 pm
This post is as close as I came to getting it nailed down. Hopefully, with a little ingenuity you’ll be able to straighten it out, cap off most of the vac lines, and have yourself a nice, running b18a1 in an EF. If you’re looking for more advice, take some pictures and send ‘em over to me!
May 16, 2008 at 11:08 pm
do i still have to get the CRX Si Engine Wiring Harness if i got a 1990 crx hf. also will the b18a1 ecu plug straight into the hf without any wiring or do i still have to wire a little? Thanks lots. and great write up helped me alot.
May 17, 2008 at 12:56 pm
Jimmy,
That’s a great question. The HF and Si wiring harnesses should be interchangeable since both are obd0 mpfi harnesses. The b18a1 ecu WILL plug in directly without modification. You could actually run your d15 on the b18a1 ecu, but it would run pretty badly.
Make sure the b18a1 is an obd0 version, not the obd1. The 90-91 was obd0, the 92-93 was obd1, and after that the b18b was introduced to replace the b18a1. Make sure you take lots of pictures!