oppositiontim

I have a 1991 Civic DPFI that I recently decided to swap a DOHC ZC into that I've had laying around for a few years.
I converted the DPFI harness to MPFI.
I wired the injectors directly to A1,3,5,7
C1 and C2 are running to the Crank Angle Sensor
The original C1 and C2 wires are moved to B10 and B12

The problem is the engine is only running on Cylinders 2 and 4.
I'm getting spark on all 4 cylinders and when I check the injector wiring, everything is checking out fine.

All 4 of the injectors are getting signal and a test light shows that they are pulsing while the engine is running.

I found that cylinders 1 and 3 are not working by pulling the plug wires while the engine was running and there's no change in the engines idle.

I replaced the distributor cap, rotor and new plugs.

I'm getting these codes on the PM6 ECU.

Code 16 - Fuel injection fault
Code 9 - CYP Cylinder position sensor
Code 10 - Air intake temp

I'm thinking it's one of two things:
1 - The distributor needs to be be replaced due to a faulty internal CYP sensor.

Would that make the ECU mess up the injectors?

2 - The ECU is faulty.

Has anyone had a similar problem?

I've done a lot of searching and I either find people with problems with No Spark or None of the injectors firing. I haven't found anyone with the problem of having spark, injectors are getting the signals from the ECU but the engine is only running on cylinders 2 and 4.

Any help would be great! Thanks

digitally_remastered

try replacing the injectors as well. you said sat for a few years, they can go bad from fuel just sitting in them. friend just had this happen to him in his 95 hatch. replaced them all and the car ran like new again.

mitsubishiv5

double check that the 2 injectors that you added to the ecu are correctly soldered/connected and that you are sure you pinned the ecu right.

Also what the guy above me said : change out the injectors. You can use any obd0 injectors, and make sure they are clipped on correctly.

jlicrx

the DOHC ZC does not have the Cylinder sensor inside the distributor - it is on the end of the exhaust camshaft - code 9 usually means the wires for the cylinder sensor are switched or not well connected or the exhaust camshaft timing is not correct

oppositiontim

I'll swap the injectors around and see if different cylinders start working with different injectors. I think I might have a set of 1989 CRX Si injectors laying around too.

I know the injector wiring is correct and I tested the wiring from the ECU to the injectors.

I thought the sensor on the exhaust cam was the Crank Angle Sensor which is Code 4 and that the Cylinder Position Sensor was inside the distributor. Am I wrong on this?

I did change the timing belt and water pump before I dropped the motor in but I double checked the timing before buttoning up the front cover and I've done multiple timing belts on Hondas in the past.

I will double check the cam timing again though.

Thanks for ideas

jlicrx

yes, you are wrong

jlicrx

what procedure did you use? did you depin wires at A1, A3, A5 an A7 and run new wires with pins from the injectors or did you just splice into the existing wires? the existing yellow wires at A1 and A3 connect together inside the harness and become one wire to the DPFI injector and the existing red wires at A3 and A7 connect together inside the harness and become one wire to the DPFI injector - if you just splice wires into the existing wires without cutting the wires at A3 and A7, you end up having the #1 and #2 injectors connected together as well as having the #3 and #4 injectors connected together - A1 goes to Inj #1, A3 goes to inj #2, A5 goes to inj #3 and A7 goes to inj #4 and they all need to be separate wires

as for the code 10, do you have the correct connector plugged into the IAT sensor? it is a white 2-wire connector with red/yellow and green/white wires

oppositiontim

Excellent info! Thanks jlicrx!

I'll check the impedance on the CYL sensor tonight after work.

When I originally did the DPFI to MPFI conversion I ran new wires for injectors 2 and 4 and used the original harness for injectors 1 and 3. Once I realized that the engine was running on cylinders 2 and 4 only, I ran new wires for injectors 1 and 3 also to see if that fixed the problem. It didn't change at all but I figured it would eliminate some possibilities.

I checked 12volts at the injector. When I click the key forward to the "run" position, all 4 injectors show 12volts for 2 seconds until the fuel pump clicks off. When the engine is running on the 2 cylinders, I can use a test light and touch the injector lead and see the test light pulsing with the injector signal on all 4 injectors.

oppositiontim

Just checked the CYL sensor and it read 860 ohms. That looks to be right where it should be. I'll check continuity next and double check the order of the wires running from C1 and C2 up to the CYL Sensor.