Hi, I am new to this forum. I bought a 03 WRX last month in pieces. Someone was trying to put an STI engine in it and decided that they were in over their head and put it up for sale. I got the car with the stock WRX engine and an STI engine (with STI wiring harness and STI ECU). I Installed the STI engine but used the WRX wiring harness and WRX ECU. I got it running but it ran like crap. I picked up a Cobb accessport and had custom Maps made by PDXtuning. I reflashed the ECU and it ran much better however it still had some kinks. When I would accelerate the engine would cut out around 4,000 RPM. The problem got worse and now it will not run at all. The access port cannot communicate with the ECU and the fuel pump is not running. I have been looking for an electrical problem such as a bad relay, or bad ground, but have found nothing. I have talked to Ryan at Vakamonmotorsports and a couple of the Subaru mechanics. It looks like my ECU may have crashed. Has anyone had any problem with this sort of thing? I would like to swap out my ECU with another 02 or 03 WRX ECU to see if this fixes the problem. Does anyone have one lying around? I have an STI ECU that I would be willing to trade for a WRX ECU if I find that changing the WRX ECU fixes the problem.

If anyone has a WRX ECU or is willing to let me use theirs just long enough to see if this is the problem I would really appreciate it.

I have a spare WRX engine, STI ECU and STI wiring harness. If any of my parts could be of ues to any of you guys let me know.

Thanks,

--Mark

 

i think your problem may be that your WRX ECu, which is for a 2.0, is trying to run a 2.5.....just a guess, but im pretty positive thats your problem, and please use your sti wireharness, there are a few items that need to be plugged in that the wrx's dont have. O and put the STi ECU in as well! $.02

-bobby

 

u need to wire up the sti harness like boobie said. thats your problem

 

Thanks for the suggestions guys.

I thought that I needed to put the STI ECU and the STI wire harness in at first too (but I took the easy route). After realizing how much work it is to change the wire harness (due to the fact that the engine and chassis harness is intergraded) I talked to PDX and Cobb (well known tuning shops) and they said that I could “Re-Flash” my WRX ECU. Doing this basically reprograms the ECU into thinking it is a STI ECU with custom tailored fuel maps and so forth. I did the Re-Flash and it ran great……well, except for the cutting out at WOT (wide open throttle) at around 4,000 RPM. The problem slowly got worse, and now it doesn’t run at all. My Cobb Accessport cannot communicate with the ECU and the fuel pump doesn’t run. I got the fuel pump to come on a time or two by turning the key on and off multiple times, and I found that the Accessport was also working. I would start the car and the fuel pump would cut out and the Accessport would again be “unable to communicate with the ECU”. I know that the two problem are related, and all the “WRX tuner guru guys” think my ECU is bad. However I don’t want to spend $500 for a used ECU if that is not the problem……..so here I am hoping to find someone who will let me use their 2002 or 2003 WRX ECU to put in my car and see if this makes it run.

It only takes about 5 minutes to take the ECU out and if anyone is willing to let me use their ECU to see if this fixes my car I will compensate them for their time.

At least then I know that I will not be spending 500 bucks on an ECU that I don’t need.

Thanks for your help…….

--Mark

 

newwrxer pm'd you

 

i have an ecu you can borrow but i need to get it back first

 

i would like to re-inerate that borrowing someones stock wrx ecu and trying it wont get you anywhere, unless your gonna reflash it which isnt any good for the guy who you borrowed it from, i think you should take a weekend or two a nd take it all apart and redo it, youll find that it isnt that hard at all. just takes time.

 

agrees and i also know that u got this car from toms friend. and by what happened to it b4 i would switch everything it will be much easier.

 

I hear where you guys are coming from, but re-wiring the car with the STI harness is no small job. The 03 WRX has cable throttle. The STI has fly by wire throttle. If I re-wire the car for the STI harness and ECU then I need to get the STI peddles, cut mine out and weld them in. Also the air conditioning units are completely different. In order to have AC I would have to get a donor STI and swap out the blower and controls. The reason this is such a big job is because unlike other cars the STI and WRX wiring harnesses for the body and the engine are one piece. This means that I would have to gut the whole car (seats, carpet, paneling) and re run the complete harness, or I would have to cut and splice the harness. The problem with splicing is that the color codes between the WXR and STI are not the same.

A agree that it can be done but…….with the current Accessport technology that is capable with Cobb tuners there is no need to do this. A reflashed WRX ECU is just as good as an STI ECU (assuming everything goes as planed with the flash process (and my situation may be the rare case that the re-flash doesn’t take correctly)). The only downside to using the WRX ECU instead of the STI ECU is that you lose the automatic capability of the variable valve timing that the STI engine has, but with the right fuel maps this can be compensated for.

The 02 or 03 WRX ECU I want to borrow WILL NOT BE RE-FLASHED!

My car ran on the stock WRX ECU when I got the STI engine installed (prior to re-flashing the ECU).

All I want to do is plug in the donor ECU and verify that my fuel pump runs and my Accessport is capable of communicating with the ECU.

If this is the case, then I can rest assured that if I spend 500 bucks to buy another WRX ECU this will fix the problem. I just have to make sure that when I re-flash it this time everything goes perfectly. I already have a new set of custom maps but I can’t reflash the current ECU because it is unresponsive.

There is a chance that my car will do the same thing with the donor ECU. In this case, no damage will be done to the donor ECU, it just means that my ECU is fine and the problem is something else (like a relay or something)

But I checked all these things already and I am 75% sure it is the ECU……..I just don’t want to buy an ECU and find that wasn’t the problem……500 bucks is a lot of money!

I appreciate everyone’s help!

--Mark

 

when dealing with an engine and the part that controls the engine, never take the easy route. Theres a reason there are different WRX and STi ECU's

 

so you getting rid of all of these? i say if your going to keep the 2.5 use the sti ecu and harness.

the wrx engine you have no use for so ill take it.

 

i think that if there was an easy way for suabru to have just reflashed a wrx ecu and BAM, now it's an sti ecu....THEY WOULD HAVE DONE IT. there's a reason the ecu from shaggy's 94 wouldn't work with his 02rs motor. yeah the harness is a B*tch, but you need it. your not going to be able to shortcut something like that, and if you do...don't throw away that wrx motor, cuz you will be doing another swap very soon. i mean seriously, this isn't a small block chevy thats just throw and go. if you plan on keeping this car, do it right. but if you don't care if it blows up, good luck with the wrx ecu.

 

why don't you just get rid of that stuff and sell it to me.

i know what to do with that stuff

 

There have been many cases where a EJ257 short block was swapped into a WRX and run with a WRX ECU. True, the STi ECU is programmed with the corect maps and will run the STi motor optimally, I see no reason why the Sti motor won't work with a WRX ECU, provided it sees the correct size injectors, which it Mark's case, it does. The only difference between Marks set up and other HIIC hybrids (like gpatmac, Chibby Goku, etc.) is Mark is running the STi heads which are better flowing, and have AVCS, which when not connected, just make for a big, heavy cam gear. In theory, Mark's set up should work fine.
-Ryan

 

If you want to I can meet you and Jess somewhere and give you his old one so you can try it in his. I had a problem with my IACV and thought it was the ECU, turns out mine was fine, so I have to giev Jess his ECU back. If we all meet then you can just take it and use it. Just a suggestion PM me if you guys wanna do that.