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hiphapa
06-22-2007, 03:47 PM
I was looking thru crxrocks thread regarding swapping a OBD1 SOHC ZC into a 89-91 CRX. Is that solely for swapping in a OBD1 SOHC Vtec ZC? I just purchased my SOHC OBD1 ZC non-Vtec and I'm looking for a good swap guide. Thanks in advance.

malichite
06-22-2007, 05:16 PM
Are you swaping the OBD1 engine into an OBD0 Car and if you are, are you converting the car to OBD1 or leaving it OBD0?

hiphapa
06-22-2007, 10:35 PM
Are you swaping the OBD1 engine into an OBD0 Car and if you are, are you converting the car to OBD1 or leaving it OBD0?

well, this is going to be my first swap so it depends on how difficult it will be to convert to OBD1.

from what i understand, to keep it OBD0, all I have to do is swap out the injectors, IM and dizzy. is this correct?

is there a benefit to converting to OBD1?

90ZCHatchling
06-22-2007, 11:52 PM
well, this is going to be my first swap so it depends on how difficult it will be to convert to OBD1.

from what i understand, to keep it OBD0, all I have to do is swap out the injectors, IM and dizzy. is this correct?

is there a benefit to converting to OBD1?



better tuning

jlicrx
06-23-2007, 02:16 AM
well, this is going to be my first swap so it depends on how difficult it will be to convert to OBD1.

from what i understand, to keep it OBD0, all I have to do is swap out the injectors, IM and dizzy. is this correct?

is there a benefit to converting to OBD1?first off, what all will need to be done will depend on what model your car is and whether it is DPFI or MPFI - all models require slightly different changes - if you have MPFI already, to run it OBD0 will only require the OBD0 distributor and a few wiring changes - if it is DPFI, you will need to do the wiring changes to convert it to run MPFI - use the engine harness that came on your car - you can swap out the injectors for the OBD0 or eliminate the injector resistor box and use the OBD1 injectors - the OBD1 engine has the MAP sensor on top of the throttle body - the OBD0 used a firewall mounted MAP - you need to extend the wires for the MAP sensor connector so that it will reach the throttle body and use that MAP - the OBD1 engine has the cooling fan switch on the thermostat housing where the OBD0 has it on the back of the block next to the oil filter - you need to extend the wires and put a different connector on in order to plug it in at the thermostat housing

if you wanted to run it OBD1, you would need an OBD0 to OBD1 ECU jumper harness from someone like Rywire and an OBD1 ECU - you would still use the harness that came on your car - you would need to rewire the distributor or get a jumper - you would need to do the same for the MAP and cooling fan switch as you would for OBD0 - unless you had the JDM SOHC ZC ECU, you would need a 4-wire O2 sensor and would need to add wiring for it - you would need to do the same with the injectors as you would for OBD0, run OBD1 injectors without resistor box or OBD0 injectors with resistor box

hiphapa
06-23-2007, 03:46 PM
first off, what all will need to be done will depend on what model your car is and whether it is DPFI or MPFI - all models require slightly different changes - if you have MPFI already, to run it OBD0 will only require the OBD0 distributor and a few wiring changes - if it is DPFI, you will need to do the wiring changes to convert it to run MPFI - use the engine harness that came on your car - you can swap out the injectors for the OBD0 or eliminate the injector resistor box and use the OBD1 injectors - the OBD1 engine has the MAP sensor on top of the throttle body - the OBD0 used a firewall mounted MAP - you need to extend the wires for the MAP sensor connector so that it will reach the throttle body and use that MAP - the OBD1 engine has the cooling fan switch on the thermostat housing where the OBD0 has it on the back of the block next to the oil filter - you need to extend the wires and put a different connector on in order to plug it in at the thermostat housing

if you wanted to run it OBD1, you would need an OBD0 to OBD1 ECU jumper harness from someone like Rywire and an OBD1 ECU - you would still use the harness that came on your car - you would need to rewire the distributor or get a jumper - you would need to do the same for the MAP and cooling fan switch as you would for OBD0 - unless you had the JDM SOHC ZC ECU, you would need a 4-wire O2 sensor and would need to add wiring for it - you would need to do the same with the injectors as you would for OBD0, run OBD1 injectors without resistor box or OBD0 injectors with resistor box

I have a 90' CRX Si, PG-MFI.

hiphapa
06-23-2007, 06:57 PM
i'd want to convert to OBD1 then. so, let me get this straight. just say I have a JDM SOHC ZC ECU, i can convert to OBD1 by simply purchasing an ecu jumper harness. I'm sorry, but the second paragraph is unclear to me. Is the JDM ZC ECU a P28?

also, anyone have experience with an ebay conversion harness? think there's much of a manufactering difference?

btw, my plans are to boost the car.

hiphapa
06-24-2007, 12:44 PM
also, i was looking into gasket sets to replace my existing ones before the install. has anyone had experience with the IM gasket that blocks off the egr and can someone explain the pros & cons of this? thanks

jlicrx
06-24-2007, 12:58 PM
also, i was looking into gasket sets to replace my existing ones before the install. has anyone had experience with the IM gasket that blocks off the egr and can someone explain the pros & cons of this? thankswhat EGR? ZCs don't have EGR

jlicrx
06-24-2007, 01:15 PM
i'd want to convert to OBD1 then. so, let me get this straight. just say I have a JDM SOHC ZC ECU, i can convert to OBD1 by simply purchasing an ecu jumper harness. I'm sorry, but the second paragraph is unclear to me. Is the JDM ZC ECU a P28?

also, anyone have experience with an ebay conversion harness? think there's much of a manufactering difference?

btw, my plans are to boost the car.the JDM OBD1 SOHC ZC ECU is a P76 - hard to find

let me try to clear up your confusion - to run it OBD1, you need an OBD1 non-VTEC ECU - you will need a OBD0 to OBD1 ECU conversion harness in order to plug your OBD0 cabin harness into the OBD1 ECU - you will need to convert the Si distributor wiring with different connector in order to connect to the OBD1 distributor (some people, like Rywire, sell a little jumper connector that you plug into the stock Si harness on one end and into the OBD1 distributor on the other end) - the US OBD1 ECUs, like P06, all use a 4 wire O2 sensor the JDM P76 ECU used 1-wire O2 sensor) - most conversion haenesses come with the wires at the ECU connectors for the 4-wire O2 - you just need to get a 4-wire O2 and extend the wires out to it - the OBD0 engines use a resistor box in the fuel injector circuit and the OBD1 injectors don't use the resistor box - you would need to remove the resistor box and modify the wiring in order to run the OBD1 injectors - you need to extend the wires for the cooling fan switch so that they will reach the OBD1 switch which is on the thermostat housing - the OBD1 switch uses a different connector which you will need to get and splice it onto the wires - you will need to disconnect the electrical connector at the MAP sensor on the firewall and extend the 3 wires so that you can plug the connector into the OBD1 MAP which is on the throttle body

i would recommecd that you not buy a conversion harness from Ebay - probably junk, like most everything else on there