89rexDX

HI ALL,

I am new here and this is my first post...

So I finally decided to swap my 1989 honda CRX DX over to MPFI after 3 years of ownership...

I proceeded to print out every MPFI swap guide I could find and read them over many times. Last month I was able to gather all the parts I would need including a complete D16Z6 intake+ throttle body, TD-18U dizzy, and a PM6 ECU.

I followed the swap guides to the letter. Soldered all my wires, got the new intake, dizzy, and ECU installed.

Now it was time for a test fire. I connect the battery and turn the key. The car cranks to life but sounds like a lawn mower, with a pronounced miss fire and smelling funky out the tail pipe. I get 1 ECU code #16 injector circuit.

I decide to go back a double check all my connections.

-All 4 injectors are known good and were cleaned and tested prior to install.
-A1,A3,A5,A7 all have good connection to injectors 1-4 in the correct order.
-I ran C1, and C2 into the engine bay and connected to the dizzy again good connection going to the right wires.
-The outside TPS sensor wires were reversed
-Double checked the thick and thin white wires at dizzy are connected correctly.

Now here is where things get odd. When all the swap guides tell me to cut the old DPFI injector plugs off and run the
DX injector (red) wire -> injector 3
Dx injector (yellow) wire -> injector 1
A3 -> injector 2
A7 -> injector 4

All of that works out fine.
Then I test the connection from the 2 yellow/ black wires that were from the DPFI injectors. I am told to solder them together and run them to resistor box. Since I am using the d16z6 high impedance injectors I dont need the resistor box. I proceeded to solder the 2 yellow/ black wires from DPFI injectors together. I then ran those 2 wires soldered together to a single wire that runs to all 4 of the yellow/ black wires on the injector harness.

I connect one side of my multi meter to yellow/ black wire on one injector connector. Then I connect the other side of the multi meter to pin A15 where the yellow/ black wires should connect for relay power they actually connect below it to pin A16 which is brown /black ground...

I could not figure this out, my wiring had never been touched before i got to it.
And the car ran fine with the DPFI setup???

So I decided to run my own wire from pin A15 on ECU to all 4 of the yellow/ black injector wires. I then did a test fire and it runs tons better. No miss fire anymore. Problem is its not running as smooth as it should and the tail pipe still smells a bit funky. Not to mention I am still getting code 16 from ECU.

Out of 7 swap guides I printed out only 2 of them talk about running a wire from A15 on ECU to resistor box or in my case directly to injector yellow/ black wires. Every other guide just said to solder the yellow/ black DPFI injector wires together and run those wires to resistor box or in my case directly to all 4 injector yellow/ black wires.

And in those 2 guides that talk about a wire running from A15, none of them say if I need to cut the wire at A15 and solder my new wire onto ECU side? or am I supposed to leave A15 connected to harness and just simply tap into it with my new wire?

So i figured maybe the crx didnt like it when I just tapped into the wire at A15 to run power to my yellow/ black injector wires. So I cut the harness side of A15 so that the wire I ran was the only thing connected to A15.

I started the car and no change. Still getting code 16.

Sorry for the long winded post but I am finally at a loss. I have checked everything in the injection circuit and I cant find any obvious problems.

The only thing I can think to check is the power relays? I read one could be bad and cause a code 16. but would my car even start if injector relay was bad?

Anyway any help is much appreciated...Thanks john

Freemananana

iTrader: (3)

4th-gen- civic.com/ecucompdpmp. htm

That is a pinout for both DPFI and MPFI OBD0 ECUs. A15 sounds right from what I see. If your car is running rough, check your vacuum lines. The MAP sensor will make your car run like crap if it doesn't have a correct vacuum source. Are you still using the MAP on the firewall or on the intake?

As for code 16 (which is probably your issue)
https://honda-tech.com/forums/tech-misc-15/need-some-technicians-help-stumped-cel-16-a-2889563/

Take a volt meter and set it to OHMs and get a reading on your injectors. Make sure they are within spec. Then take a reading from the ECU pin to the injector and try to isolate a 'bad wire'.

89rexDX

All vacuum lines have been replaced. I am currently using the stock MAP sensor that is located on the firewall. All the vacuum line plumbing should be correct. I printed out a vacuum diagram and followed that. That being said I will go double check the vacuum lines.
I still do not get why I am getting code 16. The injector wiring seems fine.
Although I am still not sure if I am supposed to tap onto the existing wire at A15 or am I supposed to cut that wire so that it no longer runs into the interior harness and only to my wire that is connected to the 4 yellow/ black injector wires?

I will check the injectors as well although I believe when I tested them before they were all at around 11.5 ohm each. Is that within spec???

89rexDX

Update: Checked all 4 injectors they read 12 ohm each... Double checked MAP vacuum hoses. it goes from charcoal can to upper port on firewall mounted MAP sensor, then from bottom port of MAP to back of intake manifold. correct?

89rexDX

I cant find any issue with power relay... any ideas guys? is there something I am not checking that could throw a code 16???

Ef4doorwagon

Well when I did the wiring for my mpfi I ran the red wires to the resistor box. The 2 injector wires on the dpfi harness to 2 injectors and the other 2 injectors wired tothe wires added from inside the car( at the ecu). I think the write up that I used was the one on Angel fire because of the pics. And as for that yellow wire from the resistor box I think I soldered that to the yellow wire on the dpfi harness and soldered it to the injector.

89rexDX

I also used the angel fire write up.
The problem is when I am told to take the 2 DPFI yellow/black wires solder them together and run that connection to either resistor box or in my case directly to injectors. Those yellow/ black DPFI wires are supposed to connect to A15 relay on ECU but when I did it I ended up connected to A16 which ends up being ground??? makes no sense.

After I ran my own wire from A15 to injectors my car runs much better, but im still getting code 16 for no apparent reason... Im stumped.

I wish now that I had let somebody else do this "easy swap" for me...

rallypoint_1

I used a pre-made harness for my MPFI swap. $160 but saved tons of hassles and headaches. I know this doesn't help your code issues but if you say F-it consider the pre made harness. Here is a link to my build. Good luck.

http://www.jdmuniverse.com/forums/ho...thread-42.html

89rexDX

I was not aware a mpfi swap harness existed. That may have been an option until I decided to go chop on my wiring harness. That and I have already spent about $350 on the swap thus far so an extra $160 really is not in the budget.

I figured if i got code 16 for injector circuit. I could check injectors to make sure they are good which they are. Then make sure they are wired to ECU in correct order and the + and - side of injectors have a good connection. I know the ECU is good it was tested twice in another civic before I bought it...

So if its not injectors, injector wiring, or ECU and I have no resistor box to go bad what could possibly be left in the "injection circuit" to check? am i missing something here?


I really hope I can find an answer to this because if not my last option is to limp it to the local mechanic and prepare to empty my wallet to get this fixed...

89rexDX

Can anybody help me out with a MPFI fuel injection troubleshooting flow chart???

I found one here

http://www.justanswer.com/uploads/hy...ic_code_16.pdf

but its for DPFI and not that helpful...

89rexDX

no ideas? wow..i figured this would be my last shot to figure this problem out. I guess ill go consult my worthless chilton manual...lol

Ef4doorwagon

A15 on your ecu harness had no wire in it?

89rexDX

ahhh..yeah I have a wire at A15? like i said before when I solder the 2 old DPFI yellow black wires together and run that to my injectors the car runs like crap because for some reason in my car those 2 yellow black DPFI wires run to A16 ground instead of A15 relay power. When I run my own wire form A15 to injectors its runs much better.


The only thing I can think of is if my PM6 si computer is not seeing a resistor box in the injector circuit, or its no liking the higher resistance of my high resistance injectors and is throwing a code 16 because of this. When I finish the brakes I am gonna go test drive it and see if it runs like it should if so I am going to ignore the code 16...

journeyquest

Dont you have to ground or tie the injectors together somehow even though your not using a resister box? I think i read that somewhere?

89rexDX

A15 runs to all 4 injectors if thats what you mean. Other then that no they are not "tied together"

Remember the injectors are negatively switched by ECU at pins A1,3,5,7. The power side (A15) is constant once key is turned on.

I have read several posts about using high resistance injectors instead of low resistance and not needing to run a resistor box because of this. Know body says anything about it causing the ECU to throw code 16 for no reason.

Any chance somebody who has done a MPFI swap with high resistance injectors could shed some light on the issue???

89rexDX

Bump...

89rexDX

Well i give up... Guess I will just cut the wire to the engine check light. I cant wait to never own a car with a computer again...1960's here I come