I swapped a JDM DOHC ZC motor into my 91 CRX. All systems functioning normally. No trouble codes on the ZC computer that came with the engine. But it will turn over but not fire. The fuel pump runs, I can hear it. the filter is new. The main relay tests OK. And all MPFI wire changes seem to check out. No Fuel is getting to the cyl. My question is, does anyone with a MPFI happen to know rough voltage numbers for injector red/black to ground, or yellow/black(inj. resistor power in) to ground. The voltage my meter is reading is very low, but as I said before the Computer is not throwing any codes, and everything else functions fine. Any help would be greatly appreciated, I've been pulling out what little hair I have for two weeks.

 

is the ground wire at the thermostat housing securely connected?

injector voltage red/black to ground should be battery voltage
resistor box voltage yellow/black to ground should be battery voltage

 

CKP wires may need to be swapped

 

I checked the ground at the thermostat, and its reading battery voltage. I've disconected diferent sensors and the computer is reading acurate troubles codes for those simulated problems. I switched the wires on the TPS sensor. What do you mean by switching CPK wires?

 

I've got battery voltage at the red black on the injectors to ground. I have no voltage between the red black and the wires going back to the ECU. I've checked my ground at the thermostat, and it's good. The wires from A1 A3 A5 A7 all show continuity. Would there be a good chance that the ECU that came with the ZC's engine, is bad. IF the Cyl pos. sensor is bad, the injectors would not fire, correct? Is there any way to test that sensor? The current at the resistor only shows when the key is on and the fuel pump is primming it's self, once the fuel pump stops current to the red blak at the injectors stop, I assume this is normal functioning. Any Ideas?

 

you also need to check the timing,
a real common problem with dohc zc motors is them skipping a tooth.
ive seen it on every dohc zc i worked on.
make sure your cams are set PRECISELY to line up at tdc.
hope this helps

 

If it skipped a tooth, would that be enough to have a complete lack of gasoline smell comming from the spark plug hole?

 

i wouldnt trust the lack of gasoline smell as a tell tale way of knowing thats the issue.
just remove the timing cover and crank it by hand, this way you will know right away.
when your crank mark on the pulley lines up with the pointer on the cover, the 'up' sign on your cams should be completely pointing up
good luck....

 

I got an Integra computer, and the car fired up. However, the car stumbled and ran really rough. I checked the valve timming and the up is pointed up. are the lines on the gears supposed to line up with the upper mating surface of the head? If so, then I'm off 2 teeth on the exhaust cam. Do you think this would have caused mechanical damage to the engine? Some say it could be off as much as 4 teeth and not make piston contact. Others say that it truely is zero tollerance. What are your thoughts?

 

the only way to know for sure is to correct the issue, and then do a compression check.
if your compression check fails then you might have caused some contact.
for this engine tho i wouldnt be too worried.
try not to guess and assume.
it goes without saying but anything is possible and you wont know untill you have substantial evidence that the valves are bent.

good luck.

 

check your injectors. My injectors that came with my dohc zc swap were stuck closed. Swapped out for some clean injectors and it fired right up.

 

I got my injectors working. the computer was bad. Although I took my valve cover off to find 3 stuck/bent intake valves. Do you hapen to know if valves and valves guides interchange with integra non v-tec heads?

 

yup you gotta use replacement parts from the 88-89 acura integra. this is the engine that was used before the b18a1.
the parts store should have the valve and seals orderable for you.
nows a great time to look at the head really good and maybe look into some porting.
or even a diff engine.
you can get the same power out of a d16z6. (sohc vtec)
imo the z6 was the demise of the dohc zc.
both great engines but the z6 is easier to get parts for...
but of course thats ultimately your decision and itll be quicker with either motor

g/l