Just wondering if anyone can shed any light on this. I'm hoping I have not done anything serious.

I have an MY00 wagon. I bought an MY99 ECU as I'm thinking of getting a remap but wanted to keep my original ECU. I put the 99 ecu in to check it. Car started first time and drove well for a few miles. The first junction I came to though the revs died and it stalled when I put the clutch in. I put my original ECU back in right away but it is now nearly stalling at junctions and the revs are hunting from nearly zero to 1100rpm at idle.

I dont know too much about ecu's and memories for errors etc. but is there a chance there were errors still logged in the 99 one or something or could changing them around have caused something to go?

Any ideas appreciated, thanks.

 

sounds like the Maf sensor tbh

 

Could it happen as suddenly as that just by swapping ecu's for about 15 minutes do you think?

 

it could happen if the ecu had learnt while the maf was slowly going wrong. When youve disconnected the ecu for a while it looses and learnt information

 

MAF.
Old ECU learnt to work with the degrading MAF.
New ECU hasn't.

If you refit your old ECU it will probably now do the same was disconnecting it from battery for a short period would of made it loose it's memory.

 

Thanks for the replies. It all seems to be pointing to the MAF. I remember a very slight hunting in the revs recently at junctions so like you say the original ecu had maybe slowly adapted. I've had a quick search and saw them at Scoobyworld for £99, does that sound about right. I dont know how much they would be from a dealer.

Is it a fairly easy DIY fit?

 

Yep that's spot on. Easy job less than a minute, disconnect plug undo 2 screws pop out the old, pop in the new re connect plug. The Maf is just after the air filter box.

 

I got the new MAF and fitted it today. When I started the engine though the check light came on which hadnt happened before. I checked the error codes by connecting the black plugs and got 23. I then tried to do a reset by connecting black + green but the light just keeps flashing 23 as I try to reset. I'm maybe doing it wrong so I've disconnected the battery just now and will try in a while. Could it be a faulty sensor from Subaru or am I missing something else?

 

Now really confused. Connected the battery again, check engine light still on, still showing code 23. Put old MAF back on CEL light goes out but still shows code 23 when the black connectors are plugged in. I think it may have to be dealer bound for this although it does seem to tick over perfectly with the new MAF on.