How To Rewire VTEC In Your Honda/Acura

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The Honda VTEC system was designed in the mid-80’s, as way to maximize both fuel efficiency and power. It uses two distinct cam profiles, one for low rpm efficiency, and the other for high rpm power.

When you’re just cruising around, the low rpm profile opens and closes the valves in a highly efficient manner. Once the revs reach 5000-6000 rpm (on average), the ECU activates a solenoid which uses highly pressurized oil to move a pin that locks the high and low rpm cam followers together. The high side cam followers respond to the more aggressive lobes on the camshaft. This cam profile holds the intake and exhaust valves open longer, which allows more fuel and air into the engine, creating significantly more power.

In order for this ingenious system to work, the ECU / VTEC controller, constantly monitors the engine temperature, oil pressure, RPMs, vehicle speed and throttle position. Using this data, the computer can determine the ideal time to activate that solenoid and switch the cam profile. Obviously, the ECU is a critical part of this Variable Valve Timing and Lift Electronic Control. And that’s why it’s so important to get the wiring correct when you’re installing a VTEC motor into a non-VTEC car.

For our example, we’ve installed an OBD 1 B16A motor into a 1995 Honda Civic CX. We’ve elected to connect the VTEC components to the ECU through the wiring harness, via the canon plug on the passenger side of the firewall. You can bypass this plug and run the wires directly through the firewall to the ECU plug. But that’s going to yield a rather messy installation.

Getting Started

First of all, don’t try to run the stock ECU with an RPM switch to activate the VTEC system. The ECU adjusts many parameters when the cam switches over, and you won’t get any of those precision adjustments if you just hotwire the solenoid to a switch. If your VTEC engine didn’t come with an ECU, go to your local junkyard and buy one (a “P28”). On the ECU barcode sticker, if you see the sequence A02, then that ECU is designed for a car with a manual transmission. Controllers marked A05 and up were designed to work with an automatic transmission. Double check to make sure that you have the right ECU for your type of transmission.

You’re also going to need several extra plug pins for cannon plugs, and the ECU plugs. They typically come in small, medium, and large. Since you’re going to need each of the different sizes, go to one of those pick-a-part salvage yards and remove several of the pins with the wire still attached.

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For the ECU plug, pry back the protective cover at the base of the wires, then use a small, sturdy tool to push the pins through from the face of the plug.

When you’re splicing wires together, make sure that you do it right. Twisting two wires together, then covering the joint with tape, is just a short waiting to happen. If you can’t solder the wires together, then at least use a good male/female plug like these.

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Under The Hood

First, you’re going need to connect the VTEC solenoid and VTEC oil pressure switch to the ECU inside the car. To do this, connect a new length of wire (BLU/BLK and GRN/YEL - with canon pins on the ends) to the VTEC hardware.

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Then run it to the canon plug by the shock tower. 

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One of the two wires on the VTEC oil pressure switch is the ground (usually black), and you can secure it to an unpainted spot on the chassis. If you’re using a VTEC harness, then you can just plug the wires in. Otherwise, plug the VTEC wires into empty slots on the canon plug.

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Using the pins and wiring that you procured from the junkyard, match the VTEC canon pins and wiring to the other side of the plug. Then feed the wiring through the firewall. Inside the car, splice the wires to their corresponding ECU pins, then insert them into the correct slot on the ECU plug. You’ll of course, need to download a wiring/plug diagram for the ECU that you plan to use.

EDITORS NOTE: We suggest you read Honda Civic/Prelude & Acura Integra OBD1 ECU Pin Schematics.

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After triple-checking all of the connections, fire up the engine and let it come up to operating temperature. If no error codes trip the CEL light, take that baby for a spin and watch that VTEC kick in!

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About Author

Hans Desjarlais is an import car enthusiast and entrepreneur who loves all things that go fast and look good. He is editor-in-chief at Import Insider and after selling his JDM engine import company in 2008, decided to offer advice and tips to import car enthusiasts. As an insider he can tell you what to look for and what to avoid. Keep in touch with him on Facebook and follow him on Twitter.

47 Comments

  1. hey i have an important question.
    i have a 95 accord lx it doesnt come with vtec..but i did the swap to a h22a4 dat came off a 2000 prelude. the engine starts and everythin now the problem is wher do i connect the vtec since i have my stock ecu?
    do i do the same as u did here or does a change alot? or do i need the ecu from the 2000 prelude?? thanks

  2. hey, do we just cut those 2 yel/blk wire for the vtec and pressure switch.do we even need those yel/blk wires.can u send me a picture how it look like after u finish from the canon plug.

  3. hi am trye to buy k20 , but my fryends tell me then h22 is betther but , i whant the more hp and trq , much i cant so what did you recomend me????????????

  4. If you’re going from a non vtec to a vtec you need to swap out the ecu and the wiring harness as well…. when purchasing the ecu and wiring harness make sure you get them from the same trasnmission type and your car.. so if you have a manual transmission you need to get an ecu and wiring harness off a manual transmission prelude

  5. im trying to do a swap to my 90 integra ls do you think that i could do a jdm 93-95 gsr or is it better to do b16a thanks.

  6. I’ve a 1999 honda prelude i just change the engine because the original one got overheated is a h22! ok so i bought a japenese engine they look the same they toll me that i just need to change the “knock sensor” from my old motor to the one i just bought but the thing is that i can’t install the sensor is blank there no where to plug it do you know why?s

  7. i have a 97 4 dr civic i want to put a v-tech with close to 200 hp but i dont know what motor will fit in the cheapest?

  8. I have a 1993 honda civic ex the engine is 1.6L I ordered an engine but was sent the wrong engine. Will a 1.5L (D15B) JAPANESE bolt into this car. The valve cover on the 1.5 has v-tec stamped on it and on the packaging they wrote D15Z6. Is it a v-tec and is $925 to much for it? It supposedly only has 36,000 miles on it. BAYOU AUTO PARTS says it will work and if I need anything to make it work they will provide it.SHOULD I START THE SWAP OR DEMAND MY MONEY BACK?????

  9. i have a 2001 honda accord EX and the inside of the muffler has alot of back carbon built up what seems to be the problem please help

  10. hi so i have a si and want to swap it into a coupe that is stock but has vtec so can i just plug it in and be fine or do i have to rewire?

  11. Hi hans007, I am running a vx engine in my 94 cx how do I wire up my o2 correctly? I am using the vx harness and ecu also. Email chalupa9151@gmail thankyou

  12. ok i have a 93 prelude si with an h22a vtec swap already done an i love it , but now i wanna do another 95 prelude h22 swap for a show car but i want something a bit faster. i know theres h22a h22a1 h22a4 an h22 type s what motor would be the best for more hp an what do i need to do the swap? i didnt do the swap in the one i have now so i dont know what the hell im doing but i wanna do it.lol email me with an info if possible sincere_1278@yahoo.com thanks

  13. Maganda Moses on

    Hi, i have a Honda Integra 1995, i recently bought a Honda V-TEC engine D15B BUT it didnt have its ECU and wiring. Is it possible to get an ECU and wiring for another Honda vehicle e.g Honda CRV and it works? The vehicle is automatic and was formally a carburator system but am changing it to EFI. Is there any information i need to know guys, am stressed by mmy my highly regarded CAR., Moses (Uganda)

  14. so called mechanic switched a 1993 non vtech eng in a prelude manual trans he put a vtec h22a
    in the prelude.car aledgidly runs ok but idles at 3000. he told my buddy to get ecu for h22a vtec which
    he shipped overnight problem not only wasn’t solved but got worse.I am no tech by no means but if you could help me
    point him in a direction we would both appreciate it.Thanks man jimstew3367

    • Hi Jim, sry for the late reply. If you haven’t figured out your problem yet, check these two things.
      1. Make sure the ECU is for a manuel (if it has J50 in the part # anywhere, that is no good.
      2. Check the vacuum lines are properly connected.

    • Hi Javier, sorry for the late reply. If your still looking for the knock sensor use the form on our site and a shop will get back to you.

  15. travise 97 civic d16y8 on

    Dood I have a 97 civic that was a dx body they did the ex motor swap I have a dx wire harness an ex ecu and an ex motor how do I wire the vtec in??

  16. I have a good question i have a 97′ honda civic coupe ,ex edition and i was wondering what would be a great motor to swap the original with? im looking for something that would really make my car fast. i was thinking about an acura engine but im not to sure about which make would be best. Any suggestions?

    • Hi Corie,

      I would go with either the Civic B16A 3rd Gen VTEC engine or the Integra B18C GSR or B18C Type-R engine. If you want to get a quote on these engines go ahead and use the “Get A Quote” form on our site and someone will get back to you with prices.

      Hans

  17. Kayce Peters on

    I am swapping an H22A into my 94 Integra LS. I bought an ECU but need to know how to get it to connect to my wire harness or how to make a jumper wire for it. Also, I am having trouble finding swap mounts for automatic transmission. I bought some but later found out they’re for manual transmission. Do you know where I could find some?

  18. chelsealianne@hotmail.co.uk on

    hi.. i had a ej1.4 p reg civic i then put a b16a2 out of a 1992…; then got a engine loom off a 1996 up.. had to change some of the clips to fit.. ( dizzy and altornator) it will still not run v tec what wire/clip needs to be in v tec or is there sumthing else wrong

  19. This site is dead on correct. I had the same problems and was having a hard time to get things to convert over. I found my sway engine at ASAP Motors locator free service. The guys shipped it to me and I found this exact problem. I have been looking everywhere for the info. Thanks!!

  20. hi..i have a honda accord SV4 single cam, i’m need to know about engine spec of H23A, can i swap it to my car?

  21. i have a 94 cx with b18b1 gsr head ls vtec i have been fight like crazy to get the vtec to work im running po6 ecu on chrome any info is welcom please…..thanks

  22. i have a 93 civic with a non vtec d15 and i just bought a d15 vtec and i kno i need the p28 ecu but what wire harness do i need to switch it without the trouble of cuttin wires an stuff

    • Hello Lucus,

      It would be much easier and cheaper for you to simply rewire the VTEC wires directly from the engine to the ECU. Otherwise you can buy a engine harness from a 92-95 Civic SOHC VTEC 1.6L.

  23. i have a 97 accord that came with the 2.2 non vtec motor. it now has the 2.3 vtec motor from a 98 accord. the problem is the vtec solenoid isnt hooked up, do i just hard wire it into the ECU? (i bought the car like this)

  24. Any chance someone has these instructions for an 02 Civic LX MT which had an EX V-TEC dropped in it, with the EX AT harness? Specifically, how to wire the secondary 02 sensor.

  25. Hi Hans,

    Good day!

    This time is the other way around. Got a honda civic 2003 with a 3 stage vtec (2solenoids) but i had this changed with a single vtec (1 solenoid only) engine from Japan. Both are the same D-series engine though the version that was released in our country have a 3 stage vtec. Japan version is a single vtec only but it has a 1.7l displacement compare to my 1.6l engine. This replacement engine is running fine but i have this engine sensor lighting everytime i i reached 100km/hr on my speedo. I believe it’s the 2nd vtec/solenoid causing this engine light error, my ecu tries to activate the 2nd vtec but it is not functioning, no connection at all. How will i bypass this sensor?

    • Did you get the ECU with the Japanese 1 stage VTEC engine? If, not you’ll need to get it or have your ECU chipped.

  26. No i don’t have it. We used the same elec’l harness and ecu since we only replaced the block and the head. Everything is ok except for this 2nd solenoid connector w/c is left hanging since the jdm head is single solenoid only. i think the ecu is ok i only need to know how will i disable the switch.

  27. my honda 94 model wouldnt start after it got burnt and i replace the complete engine wire, change the ignition and some other thing it s just rolling but dont shock

    • Hello Jun,

      Any import performance shop in your area should know how to do that. There are also guides online which explain how to do it in case they don’t. Don’t go to a dealer though, they usually never want to do things like that.

  28. reggie tapia on

    Help !!! I recently changed out a 1.7 non vtec on my 2004 honda civic LX for a 1.7 vtec japenese engine. Engine looks great I get a engine light for a bad camsensor when I drive on highway I have no problems until I floored it then the car stalls and won’t go over 3 rpms. Car will drive fast over 60 mph but when I floor it it stalls is the problem as simple as changing cam sensor or change out computer or what

    • Hans Desjarlais on

      Hi Reggie, it sounds to me like a computer problem. Is your car Auto or Manuel? Make sure you have the right computer for your engine and trans. Going along past experience, 95% of the time that issue was related to the wrong/defective computer.

  29. José García on

    I have Honda prelude 93 Non vtec engine 2.3 automatic trany.
    This engine get overheated. So
    I buy another engine When talk to the person. Told me that 2.2 a4 was the same so replace the engine but now the car wont start Use the same wire harness sensors are on the same position Know this engine come from 93 prelude. Standard trany. Please reply appreciated your time.

    • Hans Desjarlais on

      Hola José, this could be due to several reasons, unfortunately I am not a mechanic so I would recommend you have a professional mechanic or tuning shop have a look. The fact that it doesn’t start isn’t related to VTEC. I would double check to make sure the engine was properly installed and connected.

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