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zc swap

Discussion in 'General Tech and Maintenance' started by xnuout3, Jan 19, 2012.

  1. xnuout3

    xnuout3 New Member

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    Hi guys,

    It has been awhile since I have done any swaps so I need some help. What all is needed to put a jdm zc d16a sohc non vtec obd-2 emgine in to my 1991 crx si. Can I use my factory harness and ecu?? Any help would be great thanks


  2. serrilion

    serrilion In my own little world!

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    You would need to convert the motor to OBD 0 I believe and then you should be able to use your harness... also this should be in the hybrid section... just so ya know
  3. xnuout3

    xnuout3 New Member

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    Like I said I new to this sorry if I in the wrong part. How do you convert a obd2 to a obd 0 ????
  4. CAFROG

    CAFROG Honda Minion

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    I think you can use the CRX ECU, alternator, starter, complete intake manifold, throttle body, and engine harness

    That should make That OBD2 ZC in there
  5. jlicrx

    jlicrx Senior Member

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    to swap the OBD2 ZC into your Si:

    1. use your Si engine harness - more about this later
    2. use your Si injectors
    3. use your Si ECU
    4. use your Si alternator
    5. use your Si distributor
    6. you can use the ZC intake manifold and throttle body, although it will make things a little easier, as far as wiring goes, if you swap the Si intake manifold and throttle body onto the ZC - the ZC doesn't have the intake air temp sensor on the manifold and doesn't have the ECU controlled fast idle control valve on the manifold - it also has the MAP sensor on top of the throttle body where the Si has it on the firewall
    7. if you use the Si intake manifold, you will only have one wiring change to make on the Si engine harness - the ZC has the cooling fan switch on the thermostat housing - your Si has it on the back of the block next to the oil filter (2-wire connector with one black wire and one yellow with green stripe wire with a big round black rubber boot) - you will need to cut the connector off the ZC engine harness and swap it onto your Si harness so that you can plug the connector into the switch on the thermostat housing - doesn't matter which wire connects to which as it is just a switch
    8. if you were to keep the ZC intake manifold, in addition to the wiring change for the cooling fan switch, you would need to extend the wires for the MAP on the firewall so that you could plug the connector into the MAP on the ZC throttle body - you would just leave the connector for the fast idle control valve not connected - you would need to somehow incorporate an intake air temp sensor (the ZC had it in the cold air intake tube) - see picture below for one way of doing it - you would still need to use the Si injectors unless you wanted to rewire the ZC injectors using that part of the ZC engine harness and eliminate your injector resistor box - there really is no reason to use the ZC injectors - just creates more work

    intake air temp sensor

    [​IMG]
  6. Dual-500

    Dual-500 Well-Known Member

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    Do the wiring updates/changes and do it right.

    Why?

    What are you going to use for electronic engine management? I used OBD1 P06, chipped and re-mapped. There will be wiring changes needed at the ECU for engine management via a different ECU. Yes, there are adaptor harness' available - but that's a half assed solution on many levels and I recommend against it.

    While the engine could be bastardized backwards to OBD0 and run with the stock CRX ECU, it won't run to it's potential - somewhat defeats the benefits of the swap.

    I never heard of a OBD2 ZC. Someone enlighten me. I have a 4th gen JDM DOHC ZC that is OBD1 92-95 model year. My research shows that to be the last ZC made. Did I miss something?
  7. xnuout3

    xnuout3 New Member

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    the zc I found is 96-00 like i said it has been a long time since i have done this. the last one i did was around 17 years ago in my 89 ccrx. i know things have changed this is why i asked you guys.
  8. xnuout3

    xnuout3 New Member

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    As for changing things i want to keep all the si parts I can. I know the zc takes different parts like timming belt water pump. Does any one have a list of parts to use on a zc motor??
  9. Dual-500

    Dual-500 Well-Known Member

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    I didn't know the ZC variant was in production that long. Consider me enlightened!

    I suggest an ECU upgrade. I found a ~$50 adaptor harness on eBay that worked, then chopped it out of the equation and hard wired the OBD1 connectors at the ECU to the car harness. The addtional length and connector bulk at the ECU was excessive. No where to cram all that stuff, hence the hardwire job.

    I set mine up OBD1, which meant the distributor connectors had to be changed, the O2 sensor is now 4 wire instead of 1 wire. Used a P06 ODB1 ECU and socketed it and installed a modified P29 mapped EPROM.

    I suggest you research what chipset is correct for that engine and run that unless you're going for more performance and having it tuned.
  10. xnuout3

    xnuout3 New Member

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    I read somewhere where u could use a acura integra ecu just plug and play is this right?? Not sure what I'm going to do with the car. I need the motor and think i can build of the zc if i want. for now the car is daily driver
  11. CAFROG

    CAFROG Honda Minion

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    Use the Si ECU.......you are not DOHC so the Integra ECU would not work right. Maybe....if it was a DOHC ZC motor.....but it is not.
  12. jlicrx

    jlicrx Senior Member

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    he is asking about SOHC ZC non-VTEC OBD2 - SOHC ZC was offered up thru 2000 - DOHC ZC stopped in 95

    there are 2 different OBD2 SOHC ZCs (non-VTEC) - one has intake manifold like a D16Y8 and the other has intake manifold like a D16Y7 with downflow throttle body

    this is the one like the Y7

    [​IMG]
  13. Dual-500

    Dual-500 Well-Known Member

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    What kind of HP does this later model ZC rate at? I'm thinking the stock D16A6 that was rated at 108 HP at the flywheel would be much less than the ZC?

    The DOHC non-VTEC ZC I put in mine ran pretty limp with a P06 & P28 ECU. I couldn't run mine with the stock ECU because I went OBD1 and the stock ECU won't work with the OBD1 dizzy.

    It woke it up real good with the P29 map. I don't know if this applies to the SHOC late model ZC. But, suspect it does as the stock Si ECU is setup for a 108 HP application
  14. jlicrx

    jlicrx Senior Member

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    the OBD2 ZC was 120ps which is about 118hp - has 9.4:1 compression ratio - came in the JDM Integra 4-doors - here is part of brochure:

    [​IMG]
    [​IMG]
  15. jlicrx

    jlicrx Senior Member

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    if i were doing it and keeping it OBD0, i would use the 88-89 Integra PG7 ECU - 88-89 Integra had the same horsepower as the OBD2 SOHC ZC - should work fine, plus you get the added benefit of 7500rpm fuel cut-off versus the 7000 rpm fuel cut on the Si PM6 ECU - we have swapped these engines but only in OBD1 EG cars
  16. CAFROG

    CAFROG Honda Minion

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    What motor is that integra ECU for? I'm guessing SOHC
  17. jlicrx

    jlicrx Senior Member

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    88-89 Integra PG7 ECU is for the USDM D16A1 DOHC engine - only engine that was available in the Integra in U.S. in 88-89 - 86-87 Integra D16A1 DOHC ECU is also a PG7 but won't work as it is for vacuum advance ignition system and not electronic ignition advance which all 88 and later Honda D-series engines have
  18. CAFROG

    CAFROG Honda Minion

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    So the Integra DOHC ECU will run that OBD2 SOHC ZC engine?
  19. xnuout3

    xnuout3 New Member

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    ok so know another question which is better to go with zc sohc or a zc dohc?? Is there alot more to putting in the dohc????
  20. xnuout3

    xnuout3 New Member

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    also one more thing can i use a zc trans?? or should I stick with the si trans which is better

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