F23A1 to F23A4

[rudyl]

Hi,

I purchased a low mileage F23A4 (Got it super cheap) to replace my aging oil burning and leaking F23A1. As far as I can tell the two engines are virtually identical including sensors connection etc... Will the F23A1 ECU run the F23A4? Are there other thing to consider? I have already installed the replacement engine and have not yet been able to get it running. It was late last night and have not yet done much troubleshooting, but want to make sure that I don't spin my wheels for hours on to later find out that something is not compatible.

Yes I did search and did not see anything relevant

thanks in advance.

 

[nyknick1015]

it will run it perfectly fine but note the a4 is a tad bit different... the a4 is the ulev one so it has slightly different fuel maps...(supposed to be more economical and saves gas) but the A1 is no different, same sensors and everything so u should run fine... just not as great gas mileage but still good

 

[rudyl]

Thanks for the info, much appreciated.

 

[Sketch o5]

i know someone that swapped a f23a1 into his car, and tried running it on the f23a4 ecu, and it wasnt working out. or it was the other way around. either way, i heard it wasnt working. so idk about that.

 

[JMillerUA6]

The only differences that I know between the two are that the exhaust manifold on the A1 is 4-2-1 and the A4 is 4-1, and that the primary oxygen sensor is in a different spot. I also think there is something a tad bit different with the IM, but I could be wrong.

Not sure about the whole fuel map thing, as far as I know the ECU's are the same. But again, I could be wrong. If they aren't the same they're wicked cheap.

 

[Misterd0505]

i had the F23A4 in my car which replaced my stock A1.. it ran fine.. the A1 ECU will run the A4, but the A4 ECU won't run the A1. basically all that will happen is that running the A4 on the A1 ECU makes it non-Ulev... it'll be fine.

 

[Sketch o5]

i had the F23A4 in my car which replaced my stock A1.. it ran fine.. the A1 ECU will run the A4, but the A4 ECU won't run the A1. basically all that will happen is that running the A4 on the A1 ECU makes it non-Ulev... it'll be fine.

yea, thats what he had done. he swapped out his a4 with an a1 and it wouldnt work.

 

[hiddengamer7]

oh, and no 6th gen header was ever 4-2-1 from the factory, though, the 5th gen EX manifolds were like that, and they are actually what most aftermarket exhaust manifolds for our cars are based on now...

 

[rudyl]

Well, I got the car running like a champ besides a coolant leak. A hose poped off when driving to work this morning. I did have to swap the exaust manifold, but that was no big deal. It amazing the difference in power going from a motor with 200k miles to one with 50k miles.

 

[AFAccord]

Glad to hear you got it working.

Actually both ULEV and LEV motors will work with either ECU.

Here are the differences:

F23A1 LEV

• 4-2-1 Exhaust manifold design
  Narrow band primary O2 sensor
  ROM in the ECU designed to work with narrow band O2

F23A4 ULEV

• 4-1 Exhaust manifold design
  Wideband primary O2 sensor
  ECU optimized for efficiency using wideband O2

They'll both run fine on either ECU, though an LEV O2 with an ULEV O2 sensor will eventually throw a CEL for the O2 heater circuit.