changing ECU form a20a3 to a20a4

[P|eszczoH]

Hi there,
I have EDM A20A3, and i want to do test change my ECU to a20a4 ECU,
and share my opinion does it make any difference.

I was looking at my shop manual, and cant find any thing about ECU electrical pin's to check that I can just plug in this computer, or I have to revire it first.

a20a4 ECU doest not use a lambda, and egr, so i hope in a little improvement.
anyone know where to find those pins electrical schema?

[A20A1]

not sure... I'm sure you'll get more power though

[shepherd79]

you won't see any power gains. It is the same ECU except it doesn't have 02 sensor or EGR sensor.
If you don't need it, i will take it off your hand. I have been looking for one.

[thegreatdane]

you won't see any power gains. It is the same ECU except it doesn't have 02 sensor or EGR sensor.
If you don't need it, i will take it off your hand. I have been looking for one.

How do you know that, have you succeded to pull out the maps from both ecu's and then compared them?
I'm not saying they are different from each other but it's possible.
But I do know that some of the added power in the A20A4 is caused solely by mechanical differences. Whether that makes up for all of it I dont know though.

I'll put together a pin out scheme for you and get back later.

[thegreatdane]

A20A4 and A20A3 pinout

[smufguy]

without an O2 sensor you are running in a closed loop and an almost constant A/F ratio. There will be a defenite possible increase in power

[A20A1]

Oh so EGR is still there but it isn't monitored by the ECU?

[b8er]

on an a20a4 there isnt even any egr crap at all

[P|eszczoH]

you won't see any power gains. It is the same ECU except it doesn't have 02 sensor or EGR sensor.
If you don't need it, i will take it off your hand. I have been looking for one.

Sorry Shepherd79 but You see, I've had chance to ride a Porsche 924S 2,5l 150PS with O2 sensor, and than with help of a friend with out O2 sensor, and constant fuel maps. I could not belive it that it makes such a differance.
The difference is in how the car gets into high rpm in full throtle, so easilly it pushed harder, and what we did it Was first riding the "after" car, and than downgraded it to stock and ride again.

This is a kind of a project for me, I want to do a test for all of us.
I cant give You a Gtech info or so, only how it feels.
But if there will be no difference, You will know about it, and we will look after mechanical parts and the power difference between a20a3 and a20a4.

and Why do You need One ? if there is no gains :-)

And TheGreatDane , what Can I say ???
Thank You, Your the Master for me :-)

I hope I will check this ECU convertion soon.

[P|eszczoH]

Oh so EGR is still there but it isn't monitored by the ECU?

Yes, I have all that stuff now, I mean the ERG, and O2 sensor,
and All I want to do is a simple test, Is there any gain, or isnt.
If there is a gain, Its Good for all of You with strict emission control, to buy such an ECU and use it daily, than when emission control comes put the right One and pass the test.

[P|eszczoH]

yeah, a20a4 has slightly higer compression, and uses higher octane fuel.
If there will be any gain, even in my butt dyno, there will be a point to go and measure the gain.

the O2 sensor was developed for emission control, not for power.
the AFR should not be out of safe range.

[shepherd79]

Paul from Russia had A20A4 in his aerodeck and his engine didn't have EGR or O2 sensors. That is how i know that A20A4 ECU doesn't have egr or O2 sensors.

I think that ECU would great for people who want to go turbo.

[smufguy]

Or maybe Jean (carotman) can start making chips for us so we can make a USDM ecu into a EDM ecu. hehehehee

[carotman]

I could do that

However, I haven't been able to chip an 88-89 ECU yet (it doesn't have an external ROM). The 86-87 has an external ROM and the Cali emissions do have one even in 88-89.

If I could get my hands on those ECUs, I could just desolder the ROMs then match the fuel maps and see if some improvement can be done. I already got a Cali Emissions ROM that I posted here but without anything to compare, it's hard to guess things.

[smufguy]

hmmmm sounds very tempting/interesting/arousing Jean.

[Stealth]

.

[Oldblueaccord]

Running fuel injection with out a O2 sesnro for feedback doesn't make any sense to me. If it even works that way.

[Stealth]

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