MPFI Conversion for Dummies

This is my first attempt at a How-To and it will probably be over explained. But I'm hoping to answer some of the questions I had the first time I did the swap, or for someone who still don't know what all to do from the Sport Compact Car How-To(Found here (http://www.downtoground.net/knowledgebase/?p=43)

I do not claim responsibility if you mess something up attempting this swap. I will give advice the best I can for it, but if someone finds something incorrect, please feel free to correct me.

Pictures can be found HERE (http://www.automotiveforums.com/vbulletin/showpost.php?p=5832450&postcount=9).

I will list 2 ways to do this: One is reusing factory wires from a donor harness, the other is adding your own wire. The second way will be in the 2nd post, it will be a crash course on what needs to be done. The first way will be in the 3rd post, it will provide a cleaner harness, but will require a little more time, but I find it much easier. Both methods require the following in this post.

First thing is Parts:

88-91 Civic/CRX Si ECU(PM6)
88-91 Civic/CRX Si Distributor(TD02U or TD18U)
MPFI Intake Manifold(Most Civic/CRX Manifolds work, most of the time you will get a Si Manifold if you buy all the parts together)
MPFI Throttle Body(Same thing)
MPFI Injectors and Fuel Rail(Same)
MPFI Engine Harness(will be a donor)
Atleast a Haynes or Chiltons Manual for your car

You cannot just simply swap the DPFI harness and MPFI Harness. Some of the wires go to different places on the plugs to prevent this from happening. So its best to use your stock harness with any swap and modify it as needed.

Now to the work:

If the engine is still in the car: Start by removing your current DPFI Intake Manifold. Follow the instructions in your Haynes/Chiltons and you should be fine. Be sure to take a piece of tape or something and mark all the plugs and hoses you remove from it.

Once that is removed, remove your DPFI Distributor. Before you start putting on the new parts, you should decide if you want to make the changes to your harness with it still in the car, or if you want to remove it. I suggest removing it completely from the car and making the changes. I don't like leaning over the car that much and prefer the cleaner harness that can be had from removing it. If you opt to remove it, make sure you mark where every plug goes.

If you decided to leave it in: Go to the next post for the crash course on what needs to be done.

If you decided to remove it: Go to the third post. Click Here (http://www.automotiveforums.com/vbulletin/showpost.php?p=5831586&postcount=3). Scrolling works too, but clicking is faster :)

And if you just want the bare essentials of what needs to be done because you know how to do everything else: Click Here (http://www.automotiveforums.com/vbulletin/showpost.php?p=5831591&postcount=4) for the Super Simplified version.

The Crash Course

There will be 4 wires you need to add: 2 going to the distributor, 2 going to your 2 extra injectors. I would atleast suggest getting a 4 wire plug to add these to and place it on the Right side(Passenger) strut tower with the other engine harness plugs.

First 2 wires: You will notice your 2 distributors have 2 different types of plugs on them. Your DPFI has square plugs and your MPFI has round plugs. Easy fix: Take your MPFI harness and find your distributor plug. Depin the wires out of it other than the Blue/Green and Blue/Yellow, cut those a couple inches back(enough room incase you need to shortened them for any screw ups)

To Depin: Look in the open side of the plug and you will see the pins facing you. By each pin is a little plastic "peg", this is what holds it in place. Simply take a small screwdriver, pick, or paper clip and press the pin back and pull the wire out. It should pull right out with ease. OBD1 pins are a little different, and I haven't found the best way to remove them yet. They have a small white clip inside of the plug that needs to be removed by a pair of needle nose pliers and then I just pull the wire out, takes a little bit to pull it out, but it works.

Now go to your DPFI harness and depin the sqaure plug one by one, matching it up in your round plug to the wires on the distributor side of the plug. All the color match, but you will find 2 white wires. If you look closely at the plugs you will notice one is a little off from the rest of the wires(not paired up with another). It will be that way on both plugs.

Once you have your DPFI wires switched to the new plug. Solder and heat shrink your wire to the blue/green and blue/yellow wires coming off the plug. It is suggested to use the same color wires, but just as long as you don't get them mixed up, other colors will work, just make a note of it somewhere for future reference. Run your new wires over to the Right strut tower and leave some extra, we will finish that when we add your 2 new Injector wires.

To the Injectors:

On the MPFI harness, find your fuel injector plugs and cut them, you can just cut them all together down by the # 1 injector. Now find the green plug with 4 red/black wires and 1 yellow/black wire running to it, cut it also. This is your Injector Resistor plug. I would HIGHLY suggest atleast un-looming this section of the harness and pull all the red/black wires running from the injectors to the green plug.

Find your two DPFI Injector plugs on your stock harness. One will be a Green plug, the other is a brown plug, but you should have marked them anyways. Cut them. The Yellow wire should actually be Brown and ran to your #1 injector on your new MPFI. The Red wire should be Light blue and ran to the #3 Injector. Solder and heat shrink these wires to your new injector plugs. For the #2 Injector run a wire off the red wire thats on the plug to your right side strut tower. The #4 Injector will be the yellow wire and it needs to be ran to the right side tower as well.

For your Injector Resistor box, find a place to mount it on your left strut tower and take the thicker yellow/black wire on your engine harness(would be wise to test a connection between the cut end from your old injectors and the plug end before you cut it), I will get a pin location on it tomorrow. Take the thick yellow/black wire and connect it to the yellow/black wire on the green plug going to the resistor box. Loom/Tape up any exposed wires you have running to the left tower.

Now route your 4 new wires how ever you want, loom them up, tape them up, keep them together and cut them how ever you need to and install them in a 4 pin plug on your right strut tower. You can get a male/female plug from your local electronics store, hardware store maybe or salvage yard. Or if your really cheap, just crimp on some spade connectors to give you a break point on it. Not the best method, but it works.

Find a way to run these 4 wires through the fire wall and into the passenger compartment.

Pull back your carpet and remove your old DPFI ECU. Finish pulling your 4 new wires through if you haven't already.

For the Injector wiring: Your #2 Injector will need to be ran to A3. #4 Injector will be ran to A7. There are already wires there, but they are no longer needed. You can cut them and solder/heat shrink your new wires to them if you need to.

For the Distributor wiring: The current wires in C1 and C2 will need to be moved: C1 moved to B10 and C2 moved to B12. Your new Blue/Green wire will need to be pinned to C1 and your last wire will be pinned to C2.

Almost ready to install everything. One more plug to mess with in the engine bay. Find your Throttle Position Sensor plug and swap the outside wires on it(its a 3 pin plug).

Now your ready to install everything. Install your Distributor, install your Intake Manifold following your Haynes/Chiltons. Plug everything up. Your TPS sensor may need to be extended, its been a little while since I have done this. My current MPFI swap has the stock harness all unloomed, so I'm unsure if it needs to be extended or not.

Once everything is back together and plugged up, turn the key and hope you did everything correctly. Should fire right up.

Clean way

This method requires removing your factory harness and removing all the tape and loom. When you do this, make sure all plugs are marked and use some tape, wire tire, something, to still keep the wires kind of grouped together to prevent a big mess. Usually I just remove the looming and just wrap some tape around it once to keep it together.

Once you have the factory harness out, you can either go ahead and take all the loom out, be sure to mark where the factory mounting places are if you want to keep those, or you can just do it as you go. Either way you will end up with most of the harness un-loomed.

After that, go to your donor harness and remove the tape and loom from it, but don't worry about taping it up to keep it grouped.Here you need to remove all 4 injector clips and wires, the resistor box plug, and the distributor plug with the Blue/Green and Blue/Yellow wires intact.

To Depin the wires from the plug, simply look at the pin side of the plug, you will see a small tab by the pins, insert a small flathead, pick or paper clip and press the pin back and pull the wire out of the other side.

Have your Factory harness laid out on the floor, ground or table some where. We will take care of the easy plug first.

Distributor Wiring

Find your OE Square Distributor plug. Take one wire out at a time and move it over to your new Round plug, matching the colors to the distributor side of the plug. You will notice there are 2 White wires, don't worry, if you look closely you will see one is not grouped with another wire like the rest. It is this way on both plugs, so just match those 2 up.

After you get done with that, you will be left with an empty square plug which you can toss, and a new round plug with 2 new wires you need to run. Simply run them along the harness with the rest of the wires up to the main plug on the strut tower.

You can now pin them into your new 4 wire connector(can be bought from local electronics store, maybe hardware store, or local salvage yard). I love using older Honda plugs because they are easy to de-pin and move where you need to without having to cut and solder wires.

Now to the fuel injectors:

Go find your Primary and Seconday Fuel Injector plugs on your factory harness. Your Primary Injector is a Brown plug with a Red and Yellow/Black wire, your Secondary Injector is a Green plug with a Yellow and Yellow/black wire. Remove both of these from the harness, but do not de-pin them yet, just lay them to the side. Now keep in mind where they were coming out of the factory loom because you will want to run your new injectors out of there.

Now that those 2 are out of the way(for the most part). Lay down your new injector plugs and run your #1 Injector wire and #3 Injector wires to the same plug your factory injectors were in. Also run all the Red/Black wires to this side. Your #1 Injector wire will be brown wire, while the #3 will be a light blue wire.

Now depin your factory Secondary Injector's Yellow wire and replace it with your new #1 Brown wire. Next replace the factory Primary Injector's Red wire with your new #3 Light Blue wire.

Now to get power to your resistor box. See the Yellow/Black wire on the green plug? Its going to the main engine harness plug, same that your injectors are at. Now depin the Yellow/Black wire for your Primary Injector and replace it with the Yellow/Black wire coming from your Resistor box plug. Simply toss your factory injector clip and wires off in the trash or wherever, your done with it. But you still have your Secondary Injector hanging on by one wire, just cut the wire and heat shrink the end of it. You won't be replacing that with anything, but you don't want to have an open hole on the plug, so we will just leave the wire there and heat shrink it so it doesn't come in contact with anything.

This takes care of that side of it, but you still have 2 Injectors to wire in. You will be left with a Red wire for your #2 Injector and a Yellow wire for your #4 Injector. Even though you just removed this color wires from your stock harness, they do not go to that side. Run these 2 wires along your harness, taping as needed along the way, and over to the Right side strut tower where your 2 new distributor wires are. Add these to your plug over here.

One last modification to your engine harness and you should be set. Find your Throttle Position Sensor(TPS) and swap your outside 2 wires on it. If you forget to do this when you start your car, even with you not having your foot on the gas, it will think its at WOT, and as you apply pressure to the peddle it will think pressure is being released. You may want to move where this sensor comes out of the harness to where the ground wires are at the thermostat.

At this point you can wrap everything back up, loom it up, tape it up, all that fun stuff. If its possible, you can go ahead and put the harness back in and mock it up before you tape it up to make sure you have taken care of everything. This step is a little easier when everything is out of the car, but possible with it in the car. If you need to, mock your new intake manifold up with a couple nuts holding it on to make sure everything reaches and is put back where it belongs.

Installing the Manifold

Once you are happy with where everything is running and you have your new harness wrapped up. Go ahead and install it in the car for the final time. Now follow your Haynes/Chilton manual and install your new Intake Manifold. Be sure to use a new gasket.

Also go ahead and install your new MPFI Distributor. If you haven't removed the DPFI Distributor yet, make a mark along the tab on the distributor and the mounting tab on the head. Go ahead and remove the 3 bolts holding the distributor to the head. Before you unplug your plug wires, make a note of your firing order(1-3-4-2). Now remove your DPFI Distributor. You won't be able to transfer that mark you made on it to your new distributor perfectly, but you can get close. You can hold the tabs end to end to transfer the mark over, but I doubt it will be perfect. After you have your mark on there, go ahead and install it into the head and put the bolts back in snug. Line up your marks the best you can and finish tightening the bolts. Install your plug wires back on, its the same firing order as before.

After you have that done, make sure everything is plugged back where it belongs and your almost done under the hood.

ECU

Now under the hood, everything should be back to normal, except you now have a MPFI manifold on and a new 4 wire plug on the right tower.

Now take the other part of that plug and run you 4 wires out of it. If its not possible to keep the same color wires, simply make a note of the new colors and where they went to somewhere. Give yourself plenty of wire to run to the passenger foot well and give you some room to work with. Tape everything up, atleast enough to get your through the firewall and run your new wires through the firewall.

There are a couple options here: You can drill a new hole and insert a grommet on it to keep the metal off the wires, or you can make a small slit in the current rubber boot the harness is coming through and insert your wires through it. Its a little tricky on the other side either way you go because of the dash and all the components behind it, so if you choose to drill, make sure you check the other side before you drill.

Once you have the wires inside, finish pulling them through and then go back to the engine bay and finish up your wires under here. You can tape them to the current harness, or simply zip tie them. Its easier to do this after you get the wires inside because it gives you more room to work with to get them through the firewall. After you have them tied up, your done under your hood other than re-connecting your battery, unless your battery isn't under the hood, then you can close your hood.

Now to the ECU. If you haven't already, pull your carpet back and you will see a nice shiny plate there with a little hole. Remove the 4 nuts holding this down and remove it, now you have access to your ECU. You will notice there are 3 plugs going into the ECU. The first plug will have 15 spots for wires(one in the middle is empty), this one is referred to as Plug A. Your second plug will have 20 spots, this is Plug B. And your last one has 16 spots and is Plug C. Plug A is a White plug, while the other 2 are Black.

Remove all the plugs and remove the ECU. First thing you will want to do is move the wires in C1 and C2. The numbers will run with Odds on the top side of the harness(the side with the clip that holds the plug in) and Evens on the bottom. #1 being the Top Left wire looking at the backside of the plug(the wire side)

It is possible to de-pin these, but they are a little trickier and either require a really small screwdriver, paper clip, or the specail tool. It has been awhile since I did mine, so please someone help me out on this one.

If you can't de-pin them or don't feel like messing with it, cut the wire a couple inches back, still leave enough to work with on both sides. You will be moving the wire at C1 to B10, and C2 will go to B12. If your cutting wires, you can cut these back how ever far you want, you won't be needing the wires coming from B10 or B12 again. Once those 2 are moved, you can now wire in your 2 new distributor wires.

If you cut wires, just solder these into the old wires. If you depined them, cut the ends off the wires that were in B10 and B12 and solder these onto the end of your new wires. Now insert your Blue/Green wire into C1, and your Blue/Yellow wire will go into C2. The distributor wiring is done.

For that last little bit: now you will mess with Plug A. You need to run your #2 Injector wire to A3, and your #4 Injector Wire to A7. The current wires in these spots will be the same as the wires originally in Plug B. They won't be needed anymore, so you can simply cut them and reuse their ends.

After all that is done, plug up your PM6 ECU, reconnect the battery and start her up. Now you should have a MPFI intake while still retaining a stock looking harness.

And the Super Simplified Version

Swap outside TPS Sensor Wires.

Injectors:
#1: Current Yellow wire, should be brown
#2: New Red Wire ran to A3 on ECU
#3: Current Red wire, should be Light Blue
#4: New Yellow Wire ran to A7 on ECU
Red/black wires on all injectors ran to Injector Resister Box
Yellow/black wire on Resistor box plug to thick Yellow/black wire on Engine harness plug(was ran to main DPFI Injector)

Distributor:
All colors match to new plug. Solo white wire goes to solo white.
New Blue/Green wire goes to C1 on ECU
New Blue/Yellow wire goes to C2 on ECU

ECU:
Current C1 goes to B10
Current C2 goes to B12

Finish it up, go through the paces editing and taking more ideas/opinions, then reformat and sticky it... good idea Tony.

Thanks Christ. I plan on getting some pics sometime this weekend, and finishing the 2nd method.

The SCC How-to works, but it has a bunch of stuff that really isn't needed in it, like exactly why you have to make said changes. When I first did the swap I just highlighted what I needed(because I actually have the magazine, still do and its in horrible shape, been out in the car for too long). Usually by the time I actually go out and do the job, I end up with a list like my Super Simplified version. Just as long as you know how to do everything else, those are the basic things you need to remember.

There were a lot of questions I had when I first did the swap, and I still have questions sometimes. Just called Jer today about my current swap, but that was a Z6 conversion question too.

I completely understand the need to simplify the MPFI swap... If you want, I'll do a write-up of my "completely simplified/keep your original harness completely intact" write up.

My version takes only a few minutes to do the wiring, requires fewer solder joints, and does not involve cutting wires at all from your harness. I posted it in my MPFI swap thread, but that walkthrough is un-edited, and has some minor misinformation in it.

The only thing about this version of the swap is that it's harder to make it "clean" since the resistor ends up in the other side of the engine bay, or you end up adding alot more wire than you need to, things like that.

PM me and let me know, I'll build the walkthrough over the next week or so, submit it, you can check over it, and post it up if you want, kinda like an addition to the MPFI swap thing.

Thank you! Can't wait, I'll get all the parts now but I got to wait until Feb to work on my car. =(

Pictures

I don't feel like editing the original posts and adding these pics to each one, so I will just add them all here.

Main Harness Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf0057.jpg
Notice the small plastic tabs under each pin. This is what you will want to press back to remove the pin.

MPFI Injector Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf0058.jpg

TPS Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf0059.jpg
Swap the Green and Yellow wires.

TPS Plug #2
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf0060.jpg
Another look into the TPS Plug.

IACV Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf0061.jpg
This is your IACV Plug. It is Honda's standard 2 wire plug and can be plugged into many things, but it should only go to the IACV.

Injector Resistor Box Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf0062.jpg

Injector Resistor Box Plug #2
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf0063.jpg

DPFI Seconday Injector Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4008.jpg
Primary plug looks just like it, but its Brown.

MPFI Distributor Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4009.jpg
Back side of the plug, notice the White wire by itself on the bottom.

MPFI Distributor Plug #2
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4010.jpg
Other side of the plug, the White wire I mentioned earlier is on the left side here.

DPFI Distributor Plug
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4017.jpg

DPFI Distributor Plug #2
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4018.jpg
The lonely White wire is on the Left side here as well...its a little dirty.

DPFI Distributor Code
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4019.jpg
Just to show where the Distributor code is at so you can make sure you have the correct one.

DPFI Distributor Code #2
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4020.jpg
Further back shot of the code, just to give a better location of it.

PM6 ECU
http://i321.photobucket.com/albums/nn368/TheOdditie/dscf4016.jpg
The middle set of numbers/letters is what you are looking for on ECUs.

Ok, I'm done with it for now. If someone wants to add more to it or another method, please feel free. Or if you think I am mis-informing anyone about anything, please let me know and I will fix it. Its possible I missed something, especially on my "clean" method because I don't feel too well right now.

I'll get my version typed up one of these days when I'm bored, and send it to you... I won't post it here myself tho, you can make that decision.

You can post it up. Doesn't hurt to have different ways of doing it

Aight, sometime eventually. When I get bored, I'll write it all up and make it cute and nice.. and take pics of my install for a general visual idea.

tony,
I do not have the dpfi motor or engine harness I bought the car as a shell(dx) my si was complete just a rust bucket.do I disregard the dx plug on the drivers side that does not plug in to my si harness?

You can't just use the Si harness without extensive wiring. Unless you swap the complete wiring harness: engine and interior harness, you can't use the Si harness.

My suggestion would be hit a local salvage yard and find a DX harness.