1986-1993 L Series compatible ECUs - MPI

[Mark_G]

Hello all,

My apologies if I have doubled up on this topic. I'm trying to work out if, and what, ECUs are interchangeable between the MPI L Series vehicles. So far I have only found this web link

https://www.megazip.net/zapchasti-dlya- ... ne-1082591#

If it can be trusted, it lists ECU part numbers 22611 AA250.....AA450....AA470....AA490...and AA620. From my searching on the internet, some of these part numbers appear to be for vehicles from other countries.

Spoke to a wrecker on the Gold Coast and they thought that the turbo versions may have a different fuel injection rate.

I've even sent a Fax (a fax because there are no other contact details other than phone numbers) to Subaru's head office in Japan to receive information on what ECUs and model names are compatible for my 1989 MPI (non-turbo) Touring Wagon. I do not think I'll have much success, but worth a try.

Has anyone else worked out what vehicle share the same ECU for these vehicles?

[El_Freddo]

G’day Mark,

My thoughts on the EA82 MPFI is that series 1 ECUs aren’t interchangeable with series 2 ECUs and same for the turbo ECU series 1 vs series 2 and including NA setups.

The turbo stuff is just speculation as I don’t have any direct experience with it.

I might have an ECU kicking around that’ll help out. I’m hoping to check it out this weekend as it’s at my folk’s place. It’s a series 2 NA Hotwire AFM ECU

Cheers

Bennie

[Mark_G]

Thanks Bennie, much appreciated.

I will still try and find out as much as I can regarding any interchangeability that may be possible.

[El_Freddo]

What number is your ecu? The one I’ve dug out of the shed is 22611 AA620.

It’s a four plug ECU.

Cheers

Bennie

[Mark_G]

Yeah same number.

But I'm wondering if there are still variations for these ECUs. I've found ECUs with this same part number but have slight differences. And one of them being completely different. I have found ebay adds with the 22611 AA620 but the ECU is nothing like my ECU. One add was from the USA which was for a 2.5L motor (Legacy I think). Other adds using the same ECU part number have completely different plug connection configurations. My ECU has 4 plugs.

I've sent a request to Hitachi (Japan) for information to understand the codes. I don't know if this is overkill or not. But it would be handy to know what all the codes on the ECU parts label mean. Not holding my breath for a response.

My ECU parts number label is green. It has a large number 51. The other numbers are:

22611 AA620
A11-000-R33
8928

I think the 8928 is possibly a date stamp/code - 28th day of 1989??. But there are also confusing issues with this number.

A current Aust ebay add (for an ECU described as a second gen L series) has the 4 plugs but slightly different label on it:

Dark mauve label
Large number 78
22611 AA620
A11-000-48

Date stamp is confusing on this one - 9Y01

From a bit of internet searching, I have discovered that some of the ECU part number code can identify if the vehicle is LH or RH drive, has an EGR or not, is a slightly different engine etc...but I can not find anything on the ECU labelling for the EA82 engine.

The A11-000-xx component of the code could be very subtle for all I know e.g. ....air/con...power windows....clock radio...etc

This is why it would be good to get hold of a chart/table to work out what all the codes mean and therefore work out ECU compatibilities. Probably only Hitachi can assist with this.

Bennie, at a guess, I'm thinking that your ECU is likely to be compatible with my vehicle.

On a repair note. I was confused about references made to transistors when I was using the internet to trouble shoot my starting issue. There is a larger, circular transistor that is part of the coil wiring. I've worked out that where I have observed corrosion within my ECU it also could be a transistor that is built into the ECU. Some USA Subaru discussion forums have identified this built into the ECU transistor as a no-start issue.

The damaged transistor in my ECU is labeled NEC 1590....which appears to be an obsolete part now.

The USA discussion forum identifies NEC 2SC2719 being the issue and is also an obsolete product. They identify a DB139 as a replacement ECU transistor. I've had a look at some of the transistor datasheets (can not be certain if I was looking at the right datasheet for NEC1590) and I can't work much out from them. I'll have to find somewhere that repairs circuit boards and ask them to work out a suitable replacement transformer and get them to soldier it in. I'm not confident that I'll find the right transistor to replace it with and I'm definitely not confident soldiering a circuit boards. Hopefully this will make my ECU operational again.

I'm still interested in obtaining another compatible ECU...as a back up and/or to use to see if the car kicks over.

[El_Freddo]

Have a chat to your local smart phone repair shop, they’re good with corduroy boards and this ECU should be a piece of piss for them since everything is so large compared to stuff they deal with. They might even know what to substitute into the ECU for the dead, obsolete parts. It’s worth asking...

Cheers

Bennie