4AFE AC1 wiring help plus ecu related question.

[redwing0001]

I just did a conversion from my stock 5AF to a 4afe 2nd gen using JDM 4AFE ecu, 5afe harness etc.... everything now works.... Apart from the AC1 pin.

I just do not know how to connect this... I have read that a lot of people just keep this unconnected and it does not affect their idle speed, unfortunately, mine goes up to 1200 rpm when it is unconnected....

Right now I have to connected to the compressor coil line..... it works no problem but should AC1 be connected to "ground" (connecting AC1 to the compressor mag coil has this effect) when the a/c is off or should it be "unconnected" (a relay that disconnects AC1 from the compressor mag coil) when the a/c is off?

The problem I have is that when AC1 is unconnected, idle is 1200 rpm and I cannot make it go down..... but when I connect it to a/c mag coil, right now I get it to idle at 750 rpm normal temps and a/c off... a bit high considering it should be 700 rpm when hot according to a hood sticker I found.

is my ecu faulty somehow? I have no spare ecu to test so I am asking first before I get myself another one.... Thanks

on a side note, if I can get a 4age small port ecu that would be nice..... however, the ISCV on these ecus are different to the ISCV that the 2nd gen 4afe ISCV uses.... 2 pins for the 4AGE, 3 pins for the 4afe....

My best option for using a similar era ecu with minimal mods would be a 4AGE BT ecu.... I only need the following to get it working on my 5AFE harness:

4 extra wires to connect the fuel injector return wires to #10, #20, #30 and #40 ecu pins
4AGE ST/BT distributor and rewire of the dizzy wiring lines to ecu
change fuel injectors to something in the level of 277 cc, mine is 1.5 litre and not 1.6 litre to avoid over fuelling problems.

4afe to 4AGE ecu adapter made for my harness

map sensor change to 4AGE BT one..... optional but better.

Everything else is identical in the 5AFE harness

And if you are asking, I also have a knock sensor installed.... using a bracket placed in the intake side engine block near the top where the combustion chamber is... it works no problem.

[dumbass]

Ac1 is normally a 12v signal when ac is on
But if it works in reverse just wire up a change overs relay to reverse the signal

[redwing0001]

by reverse you meant connecting it to ground?

it does that automatically when you connect AC1 to the compressor mag coil... when the a/c is off, it is connected to ground since the mag coil has a ground connection at the other end of the coil....

but the question is, should it stay connected to ground even when the a/c is off.

The reason why I ask is that I built a DIY data logger for OBD 1 engines using plans I found on the internet.... its actually easy to do. just a usb to serial port, a modified connector then the software that is available on that site.

and it runs. but when I connected it to my engine, I noticed that when it was idling, it sees the a/c as on even though no power is applied to the mag coil.

so I want to know whether keeping AC1 grounded may give the ecu a signal that it gives extra gas to compensate even when there is no actual load to the engine.

I tested it by disconnecting the AC1 from the mag coil and it will say "OFF", but the idle is just way too high..... so currently I have it connected to the mag coil to keep the idle at normal 750 rpm.

This is what I am referring to: http://www.microsofttranslator.com/b....com/myengine/

[redwing0001]

UPDATE:

I just replaced the ecu..... there was a problem that I encountered with this ecu I ran...... cyl 1 and 3 Spark plugs were dry black soot while 2 and 4 are nice brown... meaning something is not correct in the ecu.... I decided to replace it.... and I got myself 2 5AFE ecus for my use.... 1 is a 1993 to 1995 5AFE ecu (89661-1A120) and the other one a 5AFE A/T (89661-1A130) both are 2nd gen and have the same pinouts..... I will just make an ecu adaptor for the A/T ecu

Plus I found a nice early 3rd gen 7AFE ecu (89661-1A280) that I can play around with.... this one may run using the 4AFE distributor, I just need to make myself a ecu adaptor so I can use this 26-16-22 ecu on my 2nd gen harness (25-16-12)...

I can verify that this is not a lean burn model..... it has the same G2 G- NE+ NE- IGF IGT pins found on 4AFE and yet, it has 4 injector outputs...