Converting Cali Civic VX to Fed (lean burn) VX
 

Those of you familiar with the Honda Civic VX know that it is a special 5th Generation Honda Civic (link: Honda Civic (fifth generation) - Wikipedia, the free encyclopedia) model with a special engine which is optimized for fuel efficiency. The 49-state (aka Federal) version of this Honda Civic model came from the factory with a 5-wire wide band O2 sensor (aka Lean Air Fuel (LAF) sensor) and an ECU that could put the engine into lean burn mode, earning it an EPA rating (link:Fuel Economy) of 39 city, 50 highway, 43 combined; one of the best EPA ratings I've ever seen for a gasoline-powered car after the Geo Metro XFi and the Honda Insight... Even the Toyota Prius hybrid does not have highway EPA ratings as high as the Federal Honda Civic VX :eek: (Of course, I know that individual drivers can get significantly better than EPA ratings)

Unfortunately, due to the slightly higher NOx emmissions that lean burn produces and due to the higher emmissions standards that California has in place, the lean burn feature could not be made available in the new Honda Civic VX models sold within California. Instead, the California models have everything the Fed models do *except* that they have ECUs which do not allow lean burn and most have a standard 4-wire O2 sensor (though I cannot confirm it, I have read that some (or maybe all) '92 Cali models did come from the factory with the 5-wire wide band LAF sensor preinstalled). The EPA rating for the California model VX is still quite good at 37 city, 45 highway, 40 combined, but for those that are dedicated (addicted?) ecomodders, switching to the Federal ECU is a fairly simple and relatively inexpensive way to gain around 5 to 10% (if not more) in fuel economy.

The instructions on how to do this are available in a variety of forms at a variety of locations on the web, but when I searched, I did not find any comprehensive and cohesive instructions in one location... So I assembled the things I did find into this one How To. I guess what I'm trying to say is that none of what I've written here is "original". I will try to give credit where it is due, and I am only adding some clarification and some personal experience in the hopes it will help others.

My philosophy when doing the conversion on my car was to do a completely reversible conversion, in case I needed to convert back to the Cali version (with narrow band O2 sensor and Cali ECU) for either smogging or for selling the car, or in case I foinked up the work. Folks that don't have this concern may find it easier and faster to chop up the stock wiring to get things connected the way they want. These instructions are not for those folks.

Cali VX owners benefit from the fact that aside from the wiring under the hood to connect the wide band LAF sensor, all the other necessary wiring is already in the main wiring harness from the engine compartment to the OBD1 connector for the ECU. So there's no need to route wires through the firewall and hack them into the OBD1 connector. That makes even the "clean" conversion I describe here really easy.

If you happen to have one of the '92 Cali models that already includes the 5-wire wide band LAF sensors, then you are lucky dogs indeed... all you have to do is swap the ECU and you are done!!

Things you will need to go get:

• Federal VX ECU: You should be able to find one of these used for relatively cheap on E-Bay. I found mine for $35, though I've seen it as high as $149. The thing to look for is the model number on the ECU... There should be a series of numbers, a dash, and then either P07-A00 or P07-A01. It does not matter which of those you get. The Cali models have P07-L00 or P07-L01.
  
  Crappy pic of the Fed ECU label:
  http://lh4.ggpht.com/_e1PWzsTgbJw/Sa...800/0cfe_1.JPG
  
  
• Wide Band LAF sensor, model L1H1: You can get a brand new one from the Honda dealer, but that will probably run you ~$400. You may be able to find used ones on E-bay, though I'm not sure I would trust a well used one. Occasionally new ones pop up at Ebay for as little as $65, though the going price seems to be closer to $170 or so. I found a nearly new Honda Factory one on E-Bay for $175.
• A set of connectors: I found these at my local Pick-N-Pull (for those that don't know - this is where a person pays a small fee to wander into the wrecking yard to pull whatever parts are needed off the limited collection of wrecked autos there... and then pays a set fee for the item pulled); I got all the connectors I wanted for free (outside of the initial entrance fee, of course). You should be able to find the needed connectors under the hood of most Hondas; you do not necessarily need to find a VX or even a 5th generation Civic. I looked for (and found) connectors that matched in color to mine in Hondas that were roughly the same generation as mine, though I think it ended up being from an Accord's engine bay. You will need:
  • One 4-pin male (needs pins 2 and 4)
  • One 8-pin female
  • One 6-pin male (needs all 6 pins)
  • One 6-pin female
    
    NOTE: I pointed out which pins are needed because there are some connectors in some cars that do not have all the pins needed for this project in them. I did not realize this until too late; I ended up with a 6-pin male that was missing one pin. Fortunately, I was able to scavenge a pin from the 4-pin connector, but it was a bugger getting it out so I could put it into the 6-pin male. If you can find connectors with the right pins in the right places to begin with, it'll save you some time.
    
    NOTE: The pins are numbered a certain way in the Honda Service Manual; see the pics below. That is the numbering scheme I am referencing within these instructions.
    
    This image is provided by user monroe74 on GasSavers.org - Fuel Efficiency, Save Gas and Gas Mileage Forum
    http://i307.photobucket.com/albums/n...oconnector.gif
    
    In this image I show how the pins are numbered using the 6-pin male & female:
    http://lh6.ggpht.com/_e1PWzsTgbJw/SZ...0/P2070066.JPG
  
  Places to harvest connectors from Hondas in the wrecking yard. The passenger shock tower will give you the 6-pin connectors; near the distributor sometimes gives you 4-pin and 8-pin connectors; and sometimes the area by the driver side shock tower has some 8-pin connectors too. Obviously, my VX has nothing on the driver side shock tower but some of the fancier models in the wrecking yard do.
  http://lh5.ggpht.com/_e1PWzsTgbJw/Sa...80069_Text.JPG
  
  Here is my collection of harvested connectors:
  http://lh5.ggpht.com/_e1PWzsTgbJw/SZ...0/P2070064.JPG
  

Once you have all the connectors, it's time to build the harness.

Tools you will need to make the harness:

• Soldering materials (iron, solder, etc)
• Wire strippers
• Electrical tape
• DMM (digital multi meter) or something with which you can test continuity
• Wiring diagram (see below)
• Wiring instructions (see below)
• Extra wire
  
  TomO provided a nice image of the wiring diagram which showed the 4-wire O2 sensor and the 5-wire O2 sensor side-by-side:
  http://thelic.org/tomo/EGR/L1H1.jpg
  
  
  Here is my "work area" as I prepared to build the harness:
  http://lh4.ggpht.com/_e1PWzsTgbJw/SZ...0/P2070067.JPG

The best instructions I found for wiring the connectors together were written by user monroe74 in this thread: Civic VX Lean Burn Questions - GasSavers.org. I've included the instructions here as well.

NOTE: The 8-pin and 4-pin connectors will be close to each other (near the LAF sensor), and the 6-pin male and female connectors will be close to each other (near the passenger shock tower connectors). The 8-pin male will have 4 wires that go to the 6-pin male; those 4 wires need to be about 2 feet long. There is another wire that goes from the 8-pin male to a ground point which needs to be about 1 1/2 ft long (18 inches). I found it helpful to know this ahead of time so that I could lay out the wires before I started the soldering.

Following these instructions, start with the 8-pin female and solder each wire first to the 4-pin male, then to the 6-pin male (and of course add the grounding wire). Then move to the 6-pin male and solder the wires between it and the 6-pin female. This should take care of all the soldering.

NOTE: Once the soldering is complete, double-check the connections between each the connectors against the wiring description using the DMM. I actually found a couple of errors in my work (kept getting confused by the odd numbering scheme of the connectors, plus I got confused by the male / female numbering). I strongly recommend you do not skip this step!

Your harness should end up looking something like this:
http://lh4.ggpht.com/_e1PWzsTgbJw/SZ...0/P2080068.JPG

When you are certain your connections have been done correctly, tape up the full length of the harness with electrical tape to protect the wires and neaten up how it all looks.

Now your harness should look something like this:
http://lh6.ggpht.com/_e1PWzsTgbJw/SZ...0/P2080070.JPG

Your next step is to get your 5-wire LAF sensor installed. This should be fairly straightforward; if you happen to have a special O2 sensor ratchet socket (one that has a slot for the wire), use that. I didn't have one, so I had to take off the heat shield around the exhaust and use an open end wrench to get the sensor out. It came out fairly easily, and I put a light coating of anti-seize on the threads of the new one to ease removal at a later time.

Connection of the harness you made should be really easy; the 8-pin female connector connects with the new O2 sensor while the 4-pin male connects where the old O2 sensor went. The 6-pin connectors go between the original 6-pin connectors on the shock tower. And the ground connects to the ground point on the engine block.

Here's a pic of the new harness connected to the 5-wire O2 sensor (can see the "shininess" of my new harness):
http://lh3.ggpht.com/_e1PWzsTgbJw/SZ...0/P2080072.JPG

Here's a pic of the new harness connected near the shock tower:
http://lh4.ggpht.com/_e1PWzsTgbJw/SZ...0/P2080074.JPG

Here's a pic of the ground point connection (G101):
http://lh4.ggpht.com/_e1PWzsTgbJw/SZ...0/P2080073.JPG

Within the passenger compartment, the ECU is behind the kick panel on the passenger side. I kinda struggled to get the carpet pulled back far enough to get to the ECU, but eventually got it out of the way enough to access the 4 connectors. Unfasten the connectors and pull the ECU free. I found it easiest to rotate the bottom of the ECU upward to the point where it was about horizontal, and then rotate the top downward. Disconnect the three connectors to free the ECU from the car and connect the Fed ECU.

Here's a pic of the ECU behind the kick panel; I had a hard time getting the carpet out of the way:
http://lh4.ggpht.com/_e1PWzsTgbJw/SZ...0/P2080075.JPG


At this point (before bolting the new ECU in place), it might be a good idea to try starting the car and maybe even go for a drive to make sure everything's working as expected. If everything seems to be working fine, Congratulations!! :thumbup: Button everything back up in the passenger compartment and enjoy the lean burn experience!

Uff... didn't realize how wordy I was... :p

hello there great thread, i was wondering though, if u live in california and you buy a 92-95 civic vx that is out of state does that mean it wont pass CA smog test because of the fed ecu & 5 wire o2 sensor? also y is it that w/ the 92 all u need is the ecu and w/ your 94 its a bit more tricky? also if with a out of state 92 civic vx do you think with a CA ecu it will pass CA smog?

thanks,

AL

Wordy is always better than having to answer question later ;)

FWIW, the 1st gen CRX HF did 41/51 in the current EPA adjustments, and it used a carb no less! I wonder what miracles the VX motor could have in the old HF shell (which has a curb weight of 1730 lbs).

Thanks for making that great post, Nacht!

newbie here, how can I know if my vx is a lean burn or not? is that the reason why at the fueleconomy.gov has 2 diferent mpg for the exact same car?

Yes, that is why there are 2 different mpg listings for the same car... the lower one is for the Cali version, the other for the 49-state version.

I think one way to tell is to look at the emissions sticker inside the hood... if it states something to the effect of "meets California emissions standards" then it's a Cali version and won't have lean burn (unless of course someone modified it). For the '92s, I understand that even the Cali version can have a 5-wire O2 sensor, so that's not an obvious indicator for that year.

... I'll have to check to see what my emissions sticker says ...

AL ...

Sorry I missed your question. It is my understanding that you wouldn't be able to bring a non-Cali VX into Cali and get it registered. The emissions sticker would prevent you from doing so, regardless of the ecu in there... a smog shop wouldn't even touch it. Also DMV checks for that sticker, so even if you got a smog shop to give you a passing cert, the DMV wouldn't accept it. There are a few exceptions to the rules (for instance, military); check Before Buying a Vehicle From Out of State - Be Sure You Can Register It in California FFVR 29 for details.

With the 5-wire O2 sensor of the '92s, it should be just a matter of swapping the ECU since the harness is already in place. That's why it's easier to get a Fed ECU into a '92 than into a later VX.

Hello everyone, I'm new to this forum but have been reading and doing research on the 49 state conversion as I'm picking up my 93 VX this weekend :)

So as I understand it, the 92 version already comes with the 5 wire 02 sensor but running on the P07-L00 (cali version). So if you have a 92 all you have to do is swap the ecu and you're good to go. Then when it comes time for smog just swap the L00 back in and you're set... right?

If the 92 cali version ecu is able to run properly with a 5 wire wideband 02 sensor, it could be assumed that any year VX running the 5 wire 02 with cali computer (possibly only the L00) should work properly within California emission requirements right? If not, what else makes the 92 version so special that it can run the 5 wire 02 with the L00 and pass smog no problem?

I'm wondering if this precautionary hack listed above (good work btw) is even necessary? Or if it's just a matter of making the 5 wire harness only and swapping ECUs when that special time comes?

That's a good question... The theory makes sense (that any year VX can use the 92 ECU plus 5-wire sensor) but I do not know if that is the case... potentially the wiring could be different (beyond the 5-wire sensor) so that the 92 ECU is not plug-n-play on a later VX. You could probably find out for sure by checking out a wiring diagram for a 92 and comparing against a 93 (you may be able to find these on-line).

I will look into it for sure. The car is a good candidate for the Fed conversion right now because it's doing the infamous part throttle hesitation. I'm debating whether to do the conversion now or just swap in the standard 4 wire 02 for the moment. This way I could have a baseline to compare from when I actually do the swap.

I have the fed model vx. passed smog in california twice no problem.

Good data point, thanks! How long ago was the last time it was smogged?

It was originally Smogged around Oct 2008, and then they made me smog it again for some reason last time I had to do my registration, which was last october(2010) i believe.

Smog is biennial in CA for most people.

Could you shed light on how to do this? Is it a matter of hacking the harness at some point between the shock tower and the 02 plug (so only one plug is needed) or would I need to create a 2 plug harness from the shock tower to the sensor? :D

Since I haven't done it, the best I can do is give you vague guidelines... basically get the wiring diagram out and cut & splice so that the 5-wire O2 sensor connects to the correct pins on the ECU. How that is accomplished is going to be up to the individual.

Thanks, do you have this wiring diagram still? It's not coming up

nevermind. Found it

Found all the plugs I needed at the local Pick your Parts on Friday and made the harness this weekend! Now I'm just waiting on my A00 ECU and L1H1 to come in the mail! Will post pics soon :D

Any advice on pulling the carpet down so it doesn't get messed up? I want to do it as clean as possible...

I got my 5 wire L1H1 sensor today but it looks like pins 3 and 4 are missing. Is this right? I'm confused now.
http://i30.photobucket.com/albums/c3...h/IMAG0106.jpg

How will D22 via pin 3 and D3 via pin 4 receive signal?

Huh?? In your picture, I see five wires. Black, white, grey, yellow, blue. There may even be a sixth wire, but if one is there it is hidden behind the others.

-soD

No, what you see is correct. There are only 5 wires. Slot 5 is empty you just can't see it. The thing that I'm boggled by is that 8 pin female connects to 8 pin male (new 5 wire 02). Pins 3 and 4 of 8 pin female in the instructions are used so they should connect to 8 pin male in the same place otherwise what's the point of those wires? Specifically,

"pin 4 needs to be wired to 6-pin male, pin 3. This line goes via C129, pin 3, and ultimately reaches D3. The old O2 sensor did not use D3. But we're taking advantage of the fact that C129 already is connected to D3, even in a CA VX."

I'm confused because on 8 pin male (new 5 wire 02) pin 4 there is no connection to the ECU.

Maybe I'm overthinking the whole thing...

I'll have to double-check my O2 sensor...

There is a calibration resistor in those two spots that don't have wires on the O2 side. the ECU reads the resistance of it and then knows how to offset the voltage reading it receives and then uses the correct Duty Cycle for the Injectors.

All is well, you've received the right LAF.

Thanks for the explanation, much appreciated!

Got everything installed, double and triple checked all my work. Started up no problem, no check engine light etc...

Only problem is, now the part throttle hesitation i was experiencing previously has gotten much worse. Car runs fine until it reaches operating temp then it bogs and forces you to give it much more gas than before. I can tell having to drive this way is going to kill my MPG for sure. It's almost as though the car won't operate in lean burn mode at all.

When i pulled the old 02 it was white if this helps any.

The car has:
correct timing
new OEM cap, wires, rotor
new NGK plugs,
new fuel pump,

My thoughts are that since the wideband setup is much more sensitive, it's amplifying the problem.

My next guess would be:
clogged EGR, (****ty mechanic said this was working fine last week)
faulty TPS,
faulty MAP

help?...

EDIT:
I just unplugged the MAP and test drove it. Idle was rough but the hesitation went away completely! Does this mean the MAP needs to be replaced or does it mean the real problem is just being masked because the car is now running in limp mode?

Never EVER drive around with a disconnected map sensor! You'll destroy your fuel economy and catalytic converter in short order! Do you have the helms service manual? If you follow the procedures in there, you should kinda be able to figure out things to try. Do you have a cracked exhaust manifold? Vacuum leaks? Cleaned the IACV? Cleaned ALL GROUNDS? When you're cleaning the grounds, do the bolts, washers, eyelets, threads with a wire brush. If there is paint on the chassis, don't scrape it off as the threads themselves are what's needed to conduct electricity. If you have an ohm meter (multimeter that can read ohms) try to get a reading from the O2 sensor to the battery and report back. Getting the ohm reading from the o2 sensor when the manifold is cold, warm and hot can also be useful.

Hello,

New to Ecomodder and recently picked up a 93 vx. I would like to convert it to fed vx(every mile counts), i already have the computer and will pick up the wide band o2 sensor soon. I just need the wiring, and will not want to mess it up eventhough there are DIY instructions(this is my daily driver). Will someone be willing to make a plug and play wire conversion? Please PM me. Thank you in advance.

Cheers.

It might be worth asking some of the Honda swap guys. Some make their own conversion harnesses, and may be able to set up one for you if they know what is required. For example, Rywire : .

Just make sure they know what exactly you are asking for and make sure you know exactly what they are going to provide. They generally make stuff to put bigger engines in smaller cars (e.g., B18C into a late-80s Civic or CRX), so "convert VX to fed" may not mean much to them.

-soD

thanks Some_other_dave for the information, will look into that, but preferably would prefer someone that has done and make one for a fee.

Cheers.

Crap whats the infamous part throttle hesitation? Cuz i think the VX motor i just swapped into my hatch is doing the same thing. I just thought this was lean burn.

I have a 94 VX. It has a 5 wire O2 sensor but the sticker on the hood says that it meets cali regulations so I'm confused. The hood has been spray painted black so it may be from a different car. How else can I verify if it is the FED version or not?

Take a look at the sticker on the ECU. P07-A00 or A01 is Fed, P07-L00 or L01 is Cali. Look it up in the startpost.

Good info here, thanks for the contributors, It is so hard to find a nice VX in showroom condition anywhere these days. I am on the look out tho!

I have never soldered in my life. Can I get away with buying a VX federal engine harness from hondaautomotiveparts and do a "plug and play" installation for my Cal->federal conversion? Rather than traveling to junkyards, gathering those plugs and learning how to solder? I have the federal ECU and 5 wire O2 sensor (NGK/NTK) already. Or would there be anything more involved than just putting the plugs together? thanks for your help.

Hello all,

New to the site, I picked up a '92 VX for my son and I'm having problems with it passing smog. It passed the Ca. 15 mph test but failed the 25 mph test. This car has the dreaded lean hesitation deal once it gets up to temp. It had a blown head gasket when we got it and that has been repaired, I did a full tuneup (plugs, cap, rotor, fuel filter, air filter, oil change, set the timing, checked the idle, replace the O2 sensor (5 wire) ran some fuel injector through the system. The smog tech told me to replace the O2 sensor and look for vacuum leaks. I did all of this but still have the hesitation. If I disconnect the O2 sensor the car runs fine but has the C.E.L. on which will not pass smog. I noticed you all mentioning this problem and was wondering if anyone has come up with a solution to it. Thanks in advance for any help you may be.

Take Care
Troy Stevens

Well I'm doing just the opposite from all of you, I'm switching from the federal ECU to the California ECU in order to get the car to pass smog, and also get rifd of the dreaded "Lean Hesitation" I just bought the Ca ECU and when it arrives I'll let you all know what happens.

Take Care
Troy

Sometimes I wonder about a partial HX conversion of my 1998 DX, but without lean burn because of our CA smog check. The ECU and the v-tec head could be of value on its own. In this thread, I posted findings from a 1990s study in which Honda claimed that v-tec without lean burn would still produce +7-8% fuel economy for the VX.

Good luck. I'll keep tabs on this thread. Sorry you did not get a response earlier. I simply don't know the answer to you previous question.

hey everybody, seems people are having fun building their own harnesses. I am building one for my brothers ca vx. found all of the parts at the junkyard, the most diffucult one to find was the six ire male. was only able to find it in post harvested condition, meaning someone had already taken the side they wanted and left me with only an inch or so to deal with. thats what you have to deal i suppose. I am excited to get the ecu and do the install to see if all of my wiring was correct! thanks to all that have contributed

I need one too ...help a fellow ecomodder
 

Wow, while you're at it...build one for me. Seriously... Please?