rplatt

So I am working on an MPFI Conversion on my CRX using a PM6 ECU, A6 dizzy, and y8 intake manifold (including y8 fuel rail, injectors, etc.). With the y8 injectors I am running without a resistor box and connected all four yellow/black wires to the two yellow/black wires from the original DX injectors. I finished everything up and the car cranks but will not start; let the troubleshooting begin. I wasn't really sure of the best way to check the injectors so I just pulled the fuel rail and tried starting the car. All four injectors sprayed at the same time for a second or two when first cranking. Is this how they are supposed to spray when initially starting the car? I have read that when it is running the injectors correspond to the spark from the distributor but I am unsure about when cranking the car. If that is not it then I am guessing it is something with the distributor (I have not been able to check for spark). I triple checked the wiring to the distributor and everything seemed good. It is very hard to tell the difference between the two white wires (one is supposedly fatter than the other). On my second inspection I thought that I had gotten them mixed up and so I switched them around but that didn't help. What are the two wires for and does anyone have a better way to tell them apart rather than one is barely fatter than the other? I should be able to check for spark tomorrow when I have someone to help me but I wanted to see if the fuel injectors are operating correctly and any ideas for the distributor wiring.

This is the guide that I am using for the wiring:
MPFI Swap

And then I used this picture to get the distributor plug wiring:
https://honda-tech.com/forums/attachmen ... zyplug.jpg

Thanks for any help you can give me!

JRCivic1

The A6 distributor is an OBD-0 part... the P06 ECU is an OBD-1 product. They are not compatible with each other. You must use an OBD-1 type distributor.

The ICM wire in the OBD-1 distributor is actually a yellow/green trace wire... it is solid white as you stated on the OBD-0 distributors. If you look closely at the distributor plug, you will see that the white ICM wire is oriented in a pair of wire locations all by itself with a weather plug in the adjacent hole, whereas, each of the three sensor pairs of wires are side by side. So, the "other" white wire will be next to an orange wire. You can also test continuity from the distributor back to the ICM output location at the ECU... which would be pin B15/17 at the original OBD-0 plugs, and through the conversion harness to pin A21/22 on the OBD-1 plug end.

rplatt

Sorry, I goofed my typing, I am using a PM6 ecu, OBD-0. I will try testing for continuity, thanks!

rplatt

Update: I picked up an in-line spark tester and I have spark. The bulb was flashing so according to that I have a problem with the fuel system. I know that the injectors are getting power because they spray fuel when I crank the car but, as I mentioned above, they all spray at the same time. They are y8 injectors so high impedance injectors which means that I run them without the resistor box. I connected the two yellow/black wires from the original dx clip (going to A13/A15 on the ECU) and then connected all of the yellow/black wires from the new injectors to those. Is this right or could it be my problem? Any ideas on what to try next? Thanks!

rplatt

Update #2: After continuing to try and make this work I decided to go the conventional route for the conversion. I went to the junkyard and picked up a resistor box and obd0 injectors wired the four red/black wires from the injectors to the red/black wires on the resistor box and then ran the yellow/black wire on the resistor box to A15 on the ECU.The other injector wires are connected to A1, A3, A5, and A7. Unfortunately that didn't solve my problem and now I am out of ideas again.

JRCivic1

Just to be clear, lets make sure your wiring is connected properly. I am not sure why you chose the A13/15 because they are associated with the main relay, so lets focus on an alternative. Connect the single red wire of the resistor box directly to the battery positive post. Injector #1 is on the driver's side closest to the cam gears and the #4 injector is closest to the distributor... make sure that each injector ground wire is connected to the proper location at the ECU. Injector #1 = A1, Injector #2 = A3, Injector #3 = A5, and Injector #4 = A7.

rplatt

I checked for continuity so the wiring is all connected properly and they are all going to the correct injectors. I ran it from A15 because that is what just about everything that I read on the conversion said to do but I am certainly willing to try other things. I will try connecting the resistor box directly to the battery. Thanks!

rplatt

I connected the resistor box directly to the battery post and it was still the same results. I am wondering if I actually solved the problem at some point but now the engine is just flooded. I pulled one of the spark plugs and it wasn't wet but it smelled very strongly of fuel and the top of the piston looked wet. Would this create a new problem causing it not to start? Any other suggestions?

JRCivic1

If the plugs are black, you will need to either replace them or clean them off and try again.

rplatt

I replaced the plugs and tried again with no luck. I pulled the fuel rail to verify that the obd0 injectors were delivering fuel and they were firing at different points (unlike when I tried using obd1 injectors and they all fired at the same time). Tested the spark plugs again to make sure that I have spark and all of them were working. I've been over my wiring about 10 times and the injectors are in the right order as are the spark plug wires. Unfortunately I am out of ideas again.

JRCivic1

If you have spark, and you have fuel actually coming out of the fuel injectors (I can't tell you how many people THINK they have fuel in the cylinder bores because they pulled the feed line at the filter and fuel came out there), then you must be out of mechanical time. Incorrect spark plug wire installation could also be an issue, but you typically hear some popping or backfire noises when this is the case.

rplatt

Thanks! It ended up being 180 degrees out of time. A little embarrassing but I put the tab that goes into the cam backwards. Hopefully someone can learn from my mistake.