Erik_Pb_Foot

long story short i'm trying to help a friend who was mislead...

car is a 99 Civic EX

motor threw a rod and he purchased a 99 DX motor. whoops, no vtec!

it's a daily driven, bone stock... all he wants is his reliability and gas mileage back.

he was told that he could simply plug in the non-vtec DX ecu that came with the motor and he wouldn't have any issues.

Motor is in and codes are flying... but it will run.

plug in the EX ecu and it runs fine also, but it throws a code b/c the vtec sensors are missing obviously...

he also mentioned an air/fuel related code but i don't know what computer that was with.... possibly both? not sure...


what has to be done to make this DX motor and DX ecu work in this EX chasis? it's a 5 speed if i remember right... not sure if that matters....


Thanks guys... he will be eternally greatful for any and all help he receives to remedy this problem.


-Erik

Erik_Pb_Foot

somebody? anybody? working in the rain isn't fun

Erik_Pb_Foot

bump for help

Erik_Pb_Foot

bumpitty bump!

ifIexplode

A dx ECU should cost less than a 100 dollars.

SiREJ8

Is the dx ecu a manual or auto ecu?

What codes are being set?

the dx has the vertical style t/b so that may have something to do with it...

Did he keep the original intake mani or use the dx one?

9hatch6

stock

Erik_Pb_Foot

the engine, to the best of my knowledge, came with a dx 5 speed ecu.

i did lots of searching but only came up with DX -> EX swaps

guess not many people are looking for an inexpensive way to keep their EX on the road

guy wasn't that specific about what code(s) was(were) being thrown.

I have to work tomorrow but i plan to head over to his house to see wxactly what is going on

If i remember right when he was talking about the swap he was going to install the DX long block with the EX intake manifold and exhaust manifold..... i could be wrong but that was what i was last told....

-Erik

pdiggitydogg

check the codes
It should work fine, 100%
The ecu could also be bad...

Erik_Pb_Foot

didn't consider a bad ecu...

so the dx ecu in the ex car with dx motor and ex manifolds should work perfect, correct?

wow that was confusing....

pdiggitydogg

All the necessary components for the DX ecu are connected, right?
The ex harness is essentially, aside from a few extra sensors (like crank angle, vtec) is the same as the dx harness. If their are just extra sensors, the ecu doesnt care, because its not programmed to see them.

As long as it is all connected properly, it should function fine...unless the ecu is bad.
See if you can find another dx ecu, locally, to test this.

For example, my chassis is EX (therefore the harness is ex also). I have an LS engine and ecu instead. The LS ecu is basically the same as the DX - I have no issues at all.

EE_Chris

A 5-spd Ex ECU controls a 2-wire IACV. A 5-spd or Auto Dx/Cx ECU controls a 3-wire IACV. An ECU that controls a 2-wire IACV will never control a 3-wire IACV and vice-versa. Which also means, if you use the Dx ECU, you're going to have to re-wire the IACV connector along with re-pinning it at the ECU connector.

pdiggitydogg

agh damn...
I totally forgot about the silly iacv wiring

Erik_Pb_Foot

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">A 5-spd Ex ECU controls a 2-wire IACV. A 5-spd or Auto Dx/Cx ECU controls a 3-wire IACV. An ECU that controls a 2-wire IACV will never control a 3-wire IACV and vice-versa. Which also means, if you use the Dx ECU, you're going to have to re-wire the IACV connector along with re-pinning it at the ECU connector.</TD></TR></TABLE>

awesome. i just talked to him and he mentioned this dilemma and wasn't sure hwo to handle it.

so essentially, the only wiring that needs to be done to make this swap run correctly with no check engine lights is to rewire the EX IACV and repin the harness to coordinate things with the DX ecu?

i want to make sure i make this totally clear as well as cut and dry for him as he is NOT a wiring guy in the least.

He should use the EX IACV since he's using the EX intake manifold, correct?

He should repin the harness at the ecu in order to fix this? if so, can anyone tell me what pins need to be moved to where?

I'm about to start searching for pinouts but i know someone will probably have responded before i find what i'm looking for.... at least i hope

-Erik &lt;---- knows B series but knows NOTHING about D's....

Erik_Pb_Foot

hummm.

pins to move?

iacv to use?

EE_Chris

What motor is he going to use? Straight up Y7 or a Mini-me (Y7 block/Y8 head)?

Erik_Pb_Foot

straight y7. his ex motor is trashed... bottom end and head....

Erik_Pb_Foot

ok quickie.... this is still a problem.... it's been sitting and he's been riding the bus for the last few weeks.

he ordered a 3 wire iacv to use on his dx motor.... i didn't know this until today when he said it came in and he coudln't mount it to the dx intake manifold.....

what do we do?

i'm sick of messing with this thing....

thanks guys

-Erik

EE_Chris

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Erik_Pb_Foot &raquo;</TD></TR><TR><TD CLASS="quote">straight y7. his ex motor is trashed... bottom end and head....</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Erik_Pb_Foot &raquo;</TD></TR><TR><TD CLASS="quote">he ordered a 3 wire iacv to use on his dx motor.... i didn't know this until today when he said it came in and he coudln't mount it to the dx intake manifold.....</TD></TR></TABLE>

On a straight up Y7, the IACV isn't mounted to the manifold. It's mounted to the throttle body.

Erik_Pb_Foot

my apologies... i'm not at his house... just going off wha ti'm being told on the phone. i'm not familiar with d series at all.....

so what is the solution to this problem? is it possible to trick the dx computer and use the 2 wire? if not, what do we need to do?

-Erik

Erik_Pb_Foot

ok... just clarified some things with him...

car is an LX, not an EX......

he has the complete LX manifold on the DX engine.... DX computer is in the car....

now i'm open again, for suggestions...

-Erik

EE_Chris

C'mon now...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Erik_Pb_Foot &raquo;</TD></TR><TR><TD CLASS="quote">is it possible to trick the dx computer and use the 2 wire? if not, what do we need to do?</TD></TR></TABLE>

I answered this above. You even quoted it in your next reply.

An LX uses the same motor as the DX - a D16Y7...and the same ECU too. So past that, what suggestions are you looking for again?

Erik_Pb_Foot

ah, he's an idiot... i went and actually saw the car today. it IS/was an EX... dunno where he got LX from.

i do understand what you suggested.... but you said to just rewire the IACV.... well if the DX computer is looking for a 3 wire IACV but the engine only has a 2 wire IACV, how could i trick it to believing there was a 3 wire IACV?

the EX intake manifold is installed on the DX engine. on the back of the DX manifold is the 2 wire IACV.

if the computer NEEDS a 3 wire IACV, the only option i see is to bolt up a 3 wire IACV.... well i can't bolt up the DX IACV to the EX manifold....

on the DX, the IACV was mounted on the throttle body.

so do i have to bolt a DX throttle body onto the ex manifold and use the included iacv? is this even possible?

if i do this, aside from creating a bottleneck, will everythign else still work fine? tps? map? will the coolant lines that flow through the EX throttle body flow through the DX throttle body the same? etc

i'm just really confused and sick of dealing with this car. this is nowhere near as easy as it should have been.

-Erik

Erik_Pb_Foot

good to go with the dx TB?

Erik_Pb_Foot

come on folks... you seem like you want to help... i just need to know if this will fix it and get him going again....