I did the MT swap on my 97 Legacy today. Everything went good and it runs great. But the mileage seems to have dropped alot. On an hour drive tonight I averaged about 15mpg.

 

For wiring all I've done is to splice the wires for the starter, and wire in the reverse light switch. I checked Josh's write up for Gen 1 Legs, and it says to cut pin 20 on the ECU connector. According to the FSM's for 97, pin 20 of the ECU harness goes to the TPS and the CTS, so I doubt that's the one I want to cut.

 

I also now have the ABS light on. The FSM's show an input to the ABS computer from the TCU. Any idea if I need to ground this or supply a voltage?

There seems to be a problem with the reply button on this thread. I could only access a reply through the quote button,

 

Have you made sure the coolent sensor for the ECU is working as it should be? A bad sensor can make the engine run rich.

Yeah, I'm an idiot...

 

I forgot to plug in the wiring harness for the MAF...

 

I'm still getting a CEL and ABS light, but it's running normal and not overly rich.

 

Last night I drove about 70 highway miles after I filled the tank, this morning i put in 7.5 gallons

Hmmm...the pin for the MT/AT identifier must have been moved on the later ones. If you have an FSM, you should be able to locate it. Depending on the model, it may require either clipping the wire, or adding a grounded wire to that terminal. If yours has the wire, clip it, if not, add one.

Yeah, I'm an idiot...

 

I forgot to plug in the wiring harness for the MAF...

 

I'm still getting a CEL and ABS light, but it's running normal and not overly rich.

 

Last night I drove about 70 highway miles after I filled the tank, this morning i put in 7.5 gallons

 

I have to wonder how the car could be running normal and have such poor mileage performance. I suggest you check for a gas leak to see if something is leaking under pressure. You also need to find out what is causing the CEL light to be turned on. Get the codes read and post them here. Perhaps they will be a clue to the trouble.

Just thought I'd update this thread for any others doing this swap.

 

I continued to have a recurring problem with the CEL returning, giving a code (I forget the #) that the ECU was having problems communicating with the TCU (it's in my basement, no wonder). I found a pin that needed to be grounded according to the FSM, #81, and that would knock out the CEL for about 90 minutes of driving, then I would have to reset it again.

 

Thanks to NJDRSubaru, I came up with an ECU out of a 97 MT last month and finally swapped it out yesterday. After a few hours of driving, no more CEL.

 

So just for everyone's info, if you're going to do this swap, grab the MT ECU out of the donor or a suitable/engine year MT.

 

I still have the ABS light on, and I've determined that I also need to come up with a MT ABS computer, but I'm not as concerned with that one...

Did the ecu recognizing the manual trans vs the auto affect the way it ran at all? I have a ej22 swap in an old GL that still thinks it is looking for an auto trans, but other than the cel it seems to run great. Just wondering if you noticed any difference other than the cel being off.

How about cruise control? Does your car have it, does it still work as it should?

 

Thanks!

Will-

Did the ecu recognizing the manual trans vs the auto affect the way it ran at all? I have a ej22 swap in an old GL that still thinks it is looking for an auto trans, but other than the cel it seems to run great. Just wondering if you noticed any difference other than the cel being off.

The car ran fine with both ECU's, I was expecting an idle issue with the AT ECU, but never noticed anything.

 

How about cruise control? Does your car have it, does it still work as it should?

I had to cut or ground one wire to get the cruise working, and then for safety I wired one of the clutch switches in series with the brake switch.

I found my post about the Cruise wiring that I posted on another board;

I also got the cruise control working again today, It was easier than I thought. On the plug on the CC unit I removed the pins 3-GY and 4-LR (LgB in Canada). That is all you need to do to get the cruise working. But, unless you wire in the front/blue switch on the clutch pedal, the engine will rev high if you have the cruise set and go on the clutch. To take care of that, splice the clutch switch into series with the 1-YW wire on the brake switch.

Great, thanks for the info!

 

Will-