Auto ecu for manual??

Nordren · Dec 26, 2013

So i bought a wiring harness and ecu for my 4.0 ohv that i plan on swapping into my 87 5 speed 4x4 manual trans. i fear that the ecu is a auto but, im not sure as it is not in my possession yet. is it possible by changing wires/pings and still have all my stuff work? or do i have to change anything out?

Nordren · Dec 27, 2013

RonD · Dec 27, 2013

If it is an ECU from an automatic then CEL(check engine light) will be on all the time because there is no "feedback" from transmission connections.
It is the software IN the ECU, not the wiring, that makes an ECU for an automatic or manual trans.

Not sure if ECU would go into "Closed loop" operation with CEL on for transmission issues.
Closed Loop is normal operation after engine is warmed up so best MPG and overall operation.
Open Loop is when engine is cold and ECU is running pre-set fuel/air mixtures, i.e. Choke Mode, O2 sensors are not used.

Open Loop after warm up is often called "Limp Mode" because if ECU can not go into Closed Loop or if sensor data or failure pulls ECU out of Closed Loop, Limp mode allows you to "limp" home or to a shop for repairs.

86 slo-vo · Dec 27, 2013

I ran an auto computer in my 4.0 for a little when I couldn't find the correct manual computer. Wasn't perfect but got me by for a while.

Nordren · Dec 28, 2013

you guys are awesome, you'll probably see threads about my truck for a bit. I'm a little inexperienced but i have my father helpin me out with this but hes an old timer with carbs and such an says he doesnt know much bout the eletronics of vehicles now a days. says it grew to fast for him to follow haha. thanks though guys!

RonD · Dec 28, 2013

This is a good site to bookmark and read up on the change over from carb to fuel injection:
http://oldfuelinjection.com/?p=1

In the level of learning about fuel injection, I am referring to the same level as most know about carbs, which is just the basics, setting idle, setting choke, setting jets, how to set float bowl level, how accelerator pump works, ported and unported vacuum.

Fuel injection is actually easier to learn than carb setup since computer does all the calculations, and fuel injection is simply more reliable and saves you money on fuel.
So you are really just learning where the data comes from(sensors) so the computer can make the correct calculations.

With carbs YOU were the computer, you had to do all the calculations, whether on paper or by ear, lol, and they never stayed the same, endless "computer" adjustments were needed over the life of the engine.

Auto ecu for manual??

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