Ok, If this sounds stupid please forgive my ignorance. I am mechanically/electrically inclined, but I am still new to the Nissan/SR20 crowd.

I bought a 91 sentra SE-R that already had a u12 DET motor swapped into it. I am not 100% that it is the u12, but it does have the stock top mount (does this mean its a u12 for sure?). Here is where I am REALLY confused - the car seems to have the stock sr20de ecu controlling the engine. The case of the ECU shows a11-b22 b98, which some googling has lead me to believe is the stock ECU. The board inside the ecu shows A12-001 B57... :confused: why two different numbers? I opened up the ecu and it does not have a daughterboard. Is there any other way that the ecu could have been flashed? I can post pics if needed, but the inside of the ECU looks like nothing has been messed with or soldered in. I am not sure what MAF the car has. I am not sure about the size of the injectors. The car supposedly has a Walbro 255, but I have not confirmed that.

Why this really confuses me is that the engine runs great; 8-9psi just fine, with no detonation or lean spots (that the ear can hear or the ass can feel). If anything the car is running a little on the rich side. The only running issue is a low almost stalling idle when the throttle is closed quickly, almost like the BAC is slow to keep up. Some research I've done on here leads me to believe this is a coolant temp sensor issue, but I would rather not change out anything till I figure out the rest of the setup.

So...is this even possible? A DE ecu running a DET engine :confused: ? I'm not having any issues other than a sometimes funky idle and poor gas mileage (~15mpg) , but I would like to have a better understanding of my setup... thanks.

Nick

Ecu part #a11-b22 b98 is for a '91 NX2K/SE-R. The other ecu, I didn't find it on JWT's list of ecus. A quick google search revealed A12-001 B57 might be a gti-r ecu. Definitely check around some more.
Does your car have any other electronics controlling air/fuel ratio?

Nope, the engine harness looks untouched and no other electronics (i assume you mean SAFC and such). I did find after some more research this guide http://www.sr20forum.com/technical-information-library/87887-howto-1-6-ga16de-2-0-sr20de-t-swap.html . In crims guide under the list of items needed for the swap he says;


Item: ECU, either JWT reflashed ECU for SR20DET, or stock SE-R ECU. I got a u12 SR20DET ECU to use with my motor.


So maybe the stock ECU can be used? I'm used to the late 80s celicas and rx7s with the flapper style air flow meters that would not be able to see the extra airflow from adding a turbo. Maybe the SE-R stock ecu and mass air flow meter was designed to calculate beyond the DE's airflow? I would think the the extra CFM going through the meter for even several PSI would put it way past its 'normal' operating area though...hmm.

Wow, so no one has done this before? Everyone using the ecu's that come with the engines for swaps eh?

it is possible to run de ecu, do you know what your a/f ratio is? might have something to do with your mileage

The case of the ECU shows a11-b22 b98, which some googling has lead me to believe is the stock ECU. The board inside the ecu shows A12-001 B57... :confused: why two different numbers?

I realized the A12 number is part number for the board. It's not something that would tell you what kind of tune is on the board.