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3rd gen ZC question

Discussion in 'Civic and CRX - EW' started by Mough, Aug 23, 2006.

  1. Mough

    Mough New Member

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    What I have, or at least what I think I have is a 3rd Gen ZC. I pulled the heat shield off and found a 92 stamped on the head. I was planning on putting it in a 91 crx but I wasnt sure if it would work since its a 3rd gan. It has grey electrical connectort and the motor mount coming out of the timing cover has studs. I read the tech article and it says the 3rd gen should also have a electrical connector at the eng of the exhaust cam but it doesnt. Also the first number under the engine code is a 3, I read somewhere that if it is a 1 its from a crx and if its a 2 its from an integra, so what did this come out of. So does anyone know if this thing will go in a 91 crx and work.
     
  2. jlicrx

    jlicrx Senior Member

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    sounds like you have OBD1 DOHC ZC - it is DOHC, correct? - yes, you can install it in your 91 CRX - you will need to decide whether you want to change the engine over to OBD0 or change the car over to OBD1

    there are a couple of things you will need to do in either case - you will need to remove the engine harness from your 91 engine and install it onto the ZC - if your CRX is a DX model, you will need to do the DPFI to MPFI wiring changes to the harness - you will need to remove the engine mount on the driver's side end of the ZC and remove the mount from your 91 block and install it onto the ZC block - the OBD1 ZC has the cooling fan switch on the thermostat housing - your 91 has the cooling fan switch on the back of the block - you will need to remove the connector for the switch from the ZC harness and install it on the 91 harness - this will require extending the wires so that the will reach the thermostat housing - the OBD1 ZC has the MAP sensor on top of the throttle body where the 91 CRX has the MAP on the firewall - you will need to extend the wires on the MAP connector and plug it into the one on the throttle body on the ZC

    in order to run the engine as OBD0, you will need a OBD0 ECU (PM7, PG7 or PM6) - you will need a distributor from 88-89 Integra and a Cylinder Position Sensor, also from 88-89 Integra - the Cylinder Sensor mounts on the end of the exhaust camshaft - if your car is HF or Si, you will need to remove the injector resistor box from the system or use OBD0 injectors from Si (not HF) - if your car is HF or Si, you will need to modify the wiring connector at the distributor

    in order to run the engine as OBD1, you need a OBD0 to OBD1 ECU jumper harness from someone like Rywire - you need OBD1 ECU (stock on OBD1 DOHC ZC is P29) - if your car is HF or Si, you will need to remove the injector resistor box from the system - you will need to install the injector clips from the ZC harness onto your 91 harness - you will need to swap out the distributor plugs from the ZC harness to your 91 harness

    that is the basics - they may be a few more things that i am forgetting right now

    DOHC ZC engines came in a lot of different models in Japan - it is probably from a Civic Ferio RTSi

    by the way, if it is 92, it would actually be a 4th gen ZC
     
    Last edited: Aug 23, 2006
  3. Mough

    Mough New Member

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    Thanks for the info jlicrx, that helps alot. Im going to run this past you just to make sure I understand what all I need to do. First I forgot to mention my car is an SI so that means no DPFI to MPFI changes are needed. I want to keep the car OBD0, so I have a PG7 ECU to use. If I want to use the ZC injectors I need to remove the resistor box or I can use my injectors from the SI motor. So does that mean that the SI injectors are low impedence and the ZC injectors are high impedence?
    Now to the distributor, you say what I need is a distributor from a 88-89 integra and the cylinder position sensor from an 88-89 Integra. Since my engine doesnt have the cylinder position sensor on the end of the exhaust cam I assume the sensor is built into the distributor that is on the engine now? If thats the way it is, is there anyway to use the distributor that is on it and rewire for the cylinder position signal?
    If not getting the other parts wont be a big deal, but I was just curious.
    If I do have to get an 88-89 Integra distributor, is there anywhere that shows how to modify the distributor harness to make it work. I hope all of this makes sence and I havnt made things more confusing. Im new to Hondas, but im used to tuning on DSMs and I have found out there is alot more to Hondas. Thanks again for your help.
     
  4. jlicrx

    jlicrx Senior Member

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    the OBD0 Si injectors are low impedance with a resistor pack and the OBD1 ZC is high impedance without the resistors - you can swap in your Si injectors if you like - the OBD1 distributor does have the Cylinder Sensor built-in, but the OBD1 distributor will not work with the OBD0 ECU - not compatible - since you have the Si wiring harness that you can swap onto the ZC, using the Si injectors will be simpler than swapping out the injector clips - the Si harness will have one connector that won't be needed on the ZC - it is for the Fast Idle Control Valve on the back of the intake manifold on the driver's side - for wiring of the distributor go here: http://www.zcspeed.com/SiZCwiring.pdf
     
  5. jlicrx

    jlicrx Senior Member

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    i did think of one other thing that is different on the OBD1 ZC - you will notice that it only has 2 vacuum ports on the front of the intake manifold - larger one for PCV valve and smaller one for the Fuel Pressure Regulator - your Si has a Purge Control Solenoid Valve on the firewall just to the right of the MAP Sensor (which you can do away with) - on the Si, there was a vacuum line from the intake manifold to the bottom of the solenoid and another line from the side of the solenoid to the charcoal canister - you will have no place to connect this line on the ZC - you could tee off of the line to the fuel pressure regulator, but i personally don't like that - if you do not have to pass a visual for emissions (and providing they even knew what they were looking for) you can just remove the entire purge system, i.e. solenoid and canister - just don't plug the line coming from the firewall to the canister (red cloth braided hose) - this is the fuel tank vent
     
  6. Mough

    Mough New Member

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    Thanks for all the info. Where im at I dont have to worry about emmissions so I was planning on taking it off anyway. I hove one more question for you though. I was wondering if it would be better for me to run with or without a cat on the ZC. I took it off my Eclipse because of the turbo, but I know loosing the backpressure on some NA engines hurts the torque, so I was just wondering what to do there.
     
  7. jlicrx

    jlicrx Senior Member

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    if you don't need cat for emissions, take it off - for the DOHC ZC, get a decent 4-2-1 header and 2" minimum to 2 1/4" maximum exhaust - ideally, you would want zero backpressure with maximum exhaust velocity - unfortunately, in order to get the desired velocity you will have to accept some increase in backpressure - the exhaust velocity creates a scavenging effect that gets rid of the exhaust faster and helps pull in more air through the intake - in order to get maximum exhaust velocity, you need the proper diameter and length header pipes, collector pipe and exhaust pipe - pipes too small result in loss of velocity due to the choking of the system (too much backpressure) and loss of power - pipes too large also result in loss of velocity (too little backpressure) and loss of power - the ideal exhaust system is one that gives you the most velocity with the least backpressure
     
    Last edited: Aug 24, 2006
  8. Mough

    Mough New Member

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    I finally got the engine in the car this week. I have been waiting on the flywheel and clutch to get back from getting chryoed. I have two cinnectors on the back side of the engine that arent blugged in. I didnt pull the engine on the car because I bought it with no engine so I done know where these go. I know you said there is one thats not used and there is supposed to be one in the back for the cooling fan. Which one is for the fan and which is for the idle switch. One has two single pin connectors in it that looke kind of like the oil pressure switch connector and the other is a two pin white connector. I know Im supposed to connect the cooling fan connector to the ZC engine but there is only one
    coolant temp sensor on the zc engine. Also there is a large vacuum connector on top of the throttle body, where does this go?
     
  9. jlicrx

    jlicrx Senior Member

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    the connector for the cooling fan switch on the Si harness is 2-wire with big black rubber boot on it (kind of like an oil pressure switch on some cars) - the wire colors are one black and one yellow with green stripe - the cooling fan switch on the ZC is not on the back of the block - it is on the thermostat housing - you need to extend the wires and install a different connector so that it will plug in - doesn't matter which wire goes where - it is just a switch

    the connector that isn't used on the Si harness is a round white 2-wire connector - the wire colors are one blue and one black with yellow stripe

    on top of the throttle body on the ZC is the MAP sensor - on the 91 Si, the MAP sensor is located on the firewall - it has a 3-wire connector that plugs into it - the wire colors are one yellow with red stripe, one white and one green with white stripe - you need to unplug the connector from the MAP on the firewall and add a short piece of wire to each of the three wires so that the connector will reach the MAP on the ZC throttle body - it will plug right in - you can get rid of the MAP on the firewall - the attached picture shows the MAP on the firewall - it is on the left and the connector is the white connector below the connector for the purge solenoid

    you will have one connector on the back of the block for the oil pressure sending unit - it is a single wire connector with yellow with red stripe wire
     

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  10. Mough

    Mough New Member

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    Thanks for the info. I got it running Friday night and I had to dig through all the parts I got in a box with the car, but I figured out the connector for the temp switch and the idle valve. I just took the whole bracket for the map sensor and the canister purge solenoid off the firewall since I dont have to worry about emmissions. The only other question I have is what do you recomend setting the timing at. I would rather be on the safe side and not have to worry about detonation rather than advance it too much and blow the top out of a piston.
     
  11. jlicrx

    jlicrx Senior Member

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