EGR WIRING any help would be awesome!!!!!!

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CIVICDM

New Member
OK kids here is what we have today 1990 honda civic base with a 1991 honda crx hf engine swapped over with MPFI my HF ecm is PM8. The wiring and ecm in civic before sway was a PM9. I want to add EGR to a non egr connector at ecm ill add my pics, i am SOOOOOOO new to honda so be NICE!!!! Any HELP!!!
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OBD0-DPFI-to-MPFI-wiring-changes.jpg
 

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jlicrx

Senior Member
VIP
I assume you are using the Civic STD engine and chassis harnesses which have been converted from DPFI to MPFI - is this correct?

Do you have the CRX HF firewall mounted control box which contains two components necessary to control the EGR system?

Be aware that the Factory Honda ECU pinout numbers on your diagrams are different from what you will see just about anywhere you look for ECU pinouts - for some unknown reason, someone decided to change the numbers and then this got published everywhere, even in some manuals purported to be "Factory Manuals". The difference is in the numbering system - Honda numbered the ECU pins on the top row of the connectors consecutively such as A1, A2, A3, A4, A5, A6, A7, A8 and then continued the numbers consecutively on the bottom row such as A9, A10, A11, A12, A13, A14, A15, A16, A17 - the other numbering that you will see most places has ODD numbers (A1, A3, A5, thru A17 on the top row - there is no A9) and EVEN numbers ( A2, A4, thru A18) on the bottom row - just something to keep in mind so you don't get confused - in fact, if you look at the connectors they have the Factory numbers right on the connectors
 

CIVICDM

New Member
I assume you are using the Civic STD engine and chassis harnesses which have been converted from DPFI to MPFI - is this correct?

Correct. But std engine/harness doesn't have a egr so where the egr plugs in and what ecm pins to use gots me lost

Do you have the CRX HF firewall mounted control box which contains two components necessary to control the EGR system?

YES! does the EGR plug into control box??
the odd A1- A-3 really screwed me up. Makes a lot of sense now!!
 
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jlicrx

Senior Member
VIP
To get the EGR working, follow this:

Please note that I have referenced the ECU pin numbers as the most commonly used convention followed by the Honda convention in parentheses i.e. A10 (A13).

First off, we will cover the control box that you will need to mount on the firewall – see the attached picture of the control box – there are four items in the box, the MAP sensor, purge cut-off solenoid valve, constant vacuum control (CVC) valve and the EGR control solenoid valve – the MAP and the purge are also on your Civic STD – you can use whichever of those that you want

on the right side of the picture you will see a bunch of circled numbers which are the vacuum lines – we will cover those later - you should have wires coming off the purge and EGR solenoid with a 4-wire connector on the end which plugs into the engine harness - wire colors on the 4-wire connector are BLACK/YELLOW, GREEN and RED – the engine harness will only have a 2-wire connector with BLACK/YELLOW and GREEN wires which connected to the purge – you will need to cut the 4-wire connector off your HF engine harness and splice it onto your STD engine harness, after cutting off the 2-wire connector – BLACK/YELLOW wires are always power – the GREEN wire is for the purge and the RED is for the EGR – when you splice the 4-wire connector on just match the wire colors, however, your engine harness won’t have anywhere to connect the RED wire on the 4-wire connector – you need to splice a new wire onto the RED wire and run it to ECU pin A10 (A13) - plug the 4-wire connector you installed into the 4-wire connector from the control box - that part of the wiring is now finished

now, we will move on to the EGR valve on the intake manifold – since you STD engine harness has no connector for the EGR valve, you will need to add wiring for it – the EGR valve has (3) wires, YELLOW/WHITE, GREEN/WHITE and YELLOW – the YELLOW/WHITE is for a 5 volt reference signal which is also used for other sensors like the TPS and ends up back at ECU pin C13 (C27), the GREEN/WHITE is ground which is also used for most of the engine sensors like the TPS, coolant temp and intake air and ends up back at ECU pin C12 (C26) – these wires can be spliced color for color into any of the wires to the other sensors – probably easiest to splice into the TPS wires somewhere back in the harness, not right at the TPS connector – for the YELLOW wire, you will need to add a new wire spliced onto the YELLOW and run it to ECU pin C8 – this should take care of all the rest of the wiring

now for the vacuum lines, see attached vacuum line diagram – the numbers on the vacuum lines match the numbers on the vacuum lines on the control box picture

this should be everything needed to get the EGR working properly.

HFcontrol_box.jpg
HFvacuum.jpg
 
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jlicrx

Senior Member
VIP
just a comment on that DPFI to MPFI wiring changes diagram - a couple of things that are not clear in the instructions - when you cut the yellow wire at A3, you connect the new red wire to the portion of the yellow wire that is left in the connector and plugs into the ECU, not the portion of the yellow wire that is left in the harness - the portion of the yellow wire remaining in the harness is spliced inside the harness to the yellow wire from A1 - likewise, when you cut the red wire at A7 and run a new yellow wire, the same thing applies
 
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