OK since talking it out most likely would be too confusing I took some pics of my question and hope they will help in someone explaining to me how it all works. Ok, there are 4 wires I need to pin in to my p28 ecu, the first picture is of the four locations (numbered) where these wires connect to the engine. The next pic is the 4 wires and the colors and butt types. Can someone please tell me which wires go where and are what. For example, wire 1 goes to connector 2, its the vtec solenoid, like that. MUCH THANKS.

ENGINE SIDE:


WIRES:

 

oh btw its a y8 head going replacing a y7 and obd2-1 conversion

 

t

 

someone, anyone?

 

Ok, which engine harness are you using and what car is this going in to? If the engine harness you are using is from a VTEC equipped motor, then you will only have to pin those wires from the shock tower to the ECU. If thats the case then you can use the pin outs from the P30. Think of it this way.....if your car was an Ex or Si that came with a P28 ECU and you swapped a DOHC Vtec you could plug you harness right into the new ECU with no rewiring. This means you can rewire your harness the same way a person wiring for a DOHC Vtec swap would. If I messed up somewhere there, someone feel free to correct me!

Ok, now my second question- where are you trying to put those wires? Are you asking where they go from the solenoid to the shock tower? or what they are for and where they go from the shock tower harness to the ECU?

 

Phil, thanks again for your help, you seem to be the guru on this subject. Ok, first off, it is a 98 civic cx hatch, I bought an obd2-obd1 harness, and a p28 computer. I need to know where on the head and intake manifold these 4 connectors go and what they are for, as well as where the opposite side (the pin wires) go. Do they go to a harness on the shock tower? I was under the impression that they went right into this obd2-obd1 harness on the obd1 side. Well hope this info helps, what can you make of it?

Thanks
Dan

 

buy a 98 ex harness.......and everything should be plug and play. no wiring nothing in the engine bay. very clean like it came from the factory.

because your engine harness goes straight to the ecu.

then plug your obd2-obd1 conversion harness into the p28 then plug the other end into the ecu harness in the car and your set.

im assuming your conversion harness looks like this........
https://honda-tech.com/zerothread?id=390600

 

Ok, I think get what you are saying..... you have four plugs that go into those sensors/harnesses and the wires pictured are the color of wires from the unknown plugs? If thats the case, then those plugs should be part of your engine harness that plugs into the shock tower. If those are just 4 wires that you need to figure out where they go and pin new harnesses to fit then yeah- as Dj Hatch said- at least get a 98 EX engine harness.

If you still need to wire for VTEC you do that from the shock tower harness to the plugs that were in your old ECU. At that point you put the conversion harness on and plug it into the P28. Sorry if that sounds confusing. feel free to PM me again.

 

By 98 ex harness do you mean the full huge harness? I have a little conversion harness which clips onto my old obd2 and the other side plugs right inot the p28, with the 98 ex wouldnt I have to take out the entire old wiring harness which as I understand is intertwined throughout the engine? As for the pics, I have four clip connectors (3 round, 1 rounded square) and those wires pictured are the wires that come off of those 4 connectors. Let me know if there is an easy way to wire it with what IO got or if I need to go buy the 98 ex harness. The conversion harness I got is skunk2s.

Thanks again
Dan

 

those circled spotts are where the round plugs fit, with the exception of #4. I need to know which plugs go where

 

By engine harness I just meant the one that goes to the engine/tranny... but that was only if these didn't have plugs.
Ok, well #1 wire should plug into #2. #2 wire square/rounded should plug into #4. The other two I'm not postive- a Helms manual would definitely help you right now. #1 in the big pic of IM looks like the IACV, so find the color of the harness for that. #3 looks like ECT, find the color of those wires and plug it in. If I'm incorrect with any of these people feel free to let him know- I own a 5th gen with a b16 so all my ish besides the VTEC sol, and VTEC pressure are different colors.

 

well since you own ek chassis car......the engine harness goes through the firewall.
hence why you have to buy the entire engine harness off a 98 ex.

96-98, 99-00 engine harnesses are in one piece and go all the way to the ecu.

92-95 civic has a chassis harness and engine harness which connect at the shock towers. unlike the ek/ej chassis which goes all the way to ecu as one assembly.

so buy a 98 ex harness so vtec is plug and play for you. allowing to use the jumper harness and p28 with factory like ease.

 

Ok according to the pinout the IACV should be green/white and the ECT red/white. I may just get the 98 ex harness, my question is if I get that harness, wouldn't it be more difficult, becuase I need to trace my cx harness through the firewall and engine and disconnect it all, and then reconnect the 98 ex, I dont know how many places the hanress connects to, so would it really be that much easier? And how much is a stock 98 ex harness? Anyway on those last two wires, those colors dont match to the pinout, so im skeptical if that config will work.

Let me know what you guys think ex harness?
Thanks
Dan

 

Good stuff DJHatch- see thats why I need to buy an EK so I can my knowledge some more I'll look at my friends Ek today and check it out.

 

GOt a look at en ex civic today and here is where the butts go:

Engine Port # : Wire #
1=2
2=1
3=4
4=3

With this info can you figure out what is what? I think 4 is the solenoid, but as for the other 3 I dont know there function or where they click in (strut tower or ecu harness).

Any ideas
Thanks
Dan

 

oop i mean

1=3
2=1
3=4
4=2

 

ttt

 

Dan, I will try to remember all i can.. Seems like you are confused.. The engine wire harness is seperate from the obd2-1 harness you have. You need to wire the ENGINE harness to 96-98 EX diagrams. Ignore the p28 for that. First off.. The round plug with the blue wire, and the black wire are the vtec oil sensor plug. The wire that is cut on that plug hook it directly to a ground on the engine. Use an eyelet, and ground it to the vtec solenoid bolt, this is a perfect spot. Ignore the knock sensor, the p28 does not look for it, therefore you dont need to wire it in. The round plug with the yellow, and black wire go to the IACV. THE YELLOW WIRE GOES TO THE RESISTOR ON THE BACK OF THE MOTOR. There should be an open spot there for it, just pin it in. Use the DX resistor, i looked it up, it is the same part number as EX. Let me do more homework and i will repost with what i find..

 

https://honda-tech.com/zerothread?id=478377
The other wire for the iacv goes into A12. Un pin the wire that is there, and pin in the black wire there.
VTEC goes into A8, this spot is not used on the CX harness, just pin it in.
VTEC pressure switch goes to C15, again this spot is not used on the CX harness.
Print out the diagrams in the link, and take note of what i have wrote, and you should be running. If you have any problems with it send me a IM.
OH i about forgot, pull out the battery, and the battery tray. And take loose the harness from inside the car. Unbolt the 2 10mm nuts that hold the harness plate to the fire wall. Run all the wires thru the plate, and rubber boot on the firewall. Do all this wiring with the ecu plugs outside the car. IE in the engine compartment with the rest of the harness still connected to the engine.
Thanks Spade for the diagrams......

 

acuratech, you are a godsend. This is exactly what I needed to know. two more things:

1. SO the only wire that pins into the p28 is the IACV

2. I can use the CX resistor on the EX manifold for the other IACV wire?

Thanks again
Dan

 

do not wire anything to the p28. The crossover harness switches it to p28 spots. The yellow wire on the IACV plug goes to the resistor. One of the spaces in the plug should be open. It will have a little plug sealing off the hole. Justpull out the little plug, and snap the pin in there. Put the IACV wire on A12 of the CX harness. There will be a wire there, yohave to unpin the wire that is there, and pin in the other wire from the IACV plug, i think it is black. All the wiring that you do is on the CX harness. Once youget done all you do is plug in the OBD2-1 harness into the p28, then plug the CX harnss into the OBD2-1 harness. When you do the wiring make positivly sure that you use the 96-98 EK pinout diagram in the link above. If you make themistake of using the EG diagram it will not work.

 

OH forgot, number 3 in your pic is alredy on the CX harness, you do not have to do anything to it.

 

excellent, and does the CX air mani have the resistor, so I can use it with the ex air mani?

Thanks
Dan

 

You talking about the intake manifold? The resistor is on the wire harness under the manifold. Yes it can be used with the EX manifold..