So guys,

I got this JDM EJ205 from JDM Racing Motors. It's in the car and will idle and run OK on my original ECU.

I bought the add on wiring kit from IA Tuning and paid for an etune for the JDM ECU also supplied by JDM Racing Motors. I believe the ECU is from a 2002 WRX with a MT. The new ECU was programmed with a base tune for the engine, but as soon as the key is turned on, the AT OIL light starts blinking indicating a communications issue.

The car is undrivable with the JDM ECU as the transmission doesn't shift right. It winds up too high and then shifts super hard. I swapped the USDM ECU back in and the AT light doesn't flash with it installed and the transmission goes back to shifting normally. The car idles and drives OK on the USDM ECU but it does have a CEL p1491, which is "PCV blow by sensor"...I don't think the JDM engine even has that sensor.

Stephen has supplied 2 tunes to try to correct the "AT light flashing/transmission won't shift right" issue and has now thrown in the towel as he says here "there appears to be a software conflict beyond my remote ability."

NOW he suggests that I should give up on the AVCS, remove the engine from the car, remove the cams, plug the oil holes in the cams for the avcs, and change the cam gears. He tells me without that the engine will be way down on power due to the avcs keeping the cams retarded.

Honestly, I'm as low as I've been in years at this point. I just can't imagine pulling the engine back out of the car. This is my kid's daily driver and school starts in 2 weeks. This project just became a nightmare.

Does anyone have any thoughts here? I'm at a loss.

Phil

i just put in a jdm AVCS motor in my suby and it runs fine (about the same as a USDM) with the AVCS retarded. i would leave it be until you get a manual transmission in that thing. or try a different jdm ECU. im guessing you have a tactrix?

Yes I have the tactrix and have my eye on a jdm ecu from an automatic wrx. I'm trying to find out from Stephen if that would be worth giving a shot.

I appreciate hearing you are happy with your car's performance with the USDM ECU. Did you have issue with the p1491 CEL for the blow by sensor? If so, did you find out how to get the CEL to turn off?

Phil

i swapped my entire manifold and wiring harness so the ecu does not know the difference. i was not "happy" with how it ran without AVCS, but its not an issue. i hooked up all the wiring to get it to work and it has a ton more torque than the non avcs motor. i have been running the carberry rom on a jdm ecu for a year now and finally got an AVCS motor to match, and got the wiring to work.

if you have the tactrix get romraider software (im guessing you have ECUflash) and disable the code and reflash it. or you can just put a jumper in the old plug for the pcv. its not a sensor its just a piece of metal that shorts out the plug.

I am using the JDM wiring harness that came on the engine. I don't think it has that plug.

I need to learn how to disable the code, as I have no clue. I do have a working tactrix cable, ecuflash and romraider working on my laptop. If anyone can advise me on the procedure to disable p1491 in my USDM ECU using that, it would be much appreciated.

I'm also wondering now if the communications issue might not even be with the ECU. Maybe the trouble lies with my car's TCU. Anyone have a clue if a JDM TCU and a USDM TCU are identical?

Phil

I know an AT ecu can be flashed for manual but you should ask Stephen if a MT can be flashed with an AT rom. I don't know if there's circuits missing on the MT ecu. My AT ecu is working well with my MT car. Have you taken the ecu apart to see if it's damaged in any way? I picked my swap up in person and was able to do this right in front of them before I paid for anything. Based on the AT light coming on and not shifting smoothly makes me think MT to AT isn't compatible like AT to MT is.

you read the ROM from the ECU, then romraider allows you to open the rom and disable a code. then you load the modified version onto the ECU using ECUflash.

im pretty sure all ECU are the same essentially. there is a pin on the ecu (pin E1) called TID (transmission identification). that is grounded or not grounded depending on manual or auto transmission.

You're saying the ground is accomplished via software, correct?

I've offered to get a JDM Automatic ECU and so far Stephen has not indicated that is necessary. He's buffaloed. After returning my money for the e-tune he's sent me 5 more tunes to try. Hard for me to complain about that kind of customer service.

I have a plan though:

1. Try the other 4 tunes he sent me tonight and verify if they fix the AT issue.
2. When they don't (I'm a realist), repay him the tuning fee and work with the USDM ECU to get the best tune he can with it and non-functional AVCS.
3. Figure out how to fix the avcs.
4. Pay Stephen to tune that.
5. Live a happy life.

Phil

no im pretty sure the pin gets grounded by the wiring harness depending on what the car has for a transmission. when the ECU sees the pin pulled down it knows to enable automatic or manual transmission maps. but its mostly to do with idle rpm and things like that. it sounds like you have something wrong somewhere else. could it be that the engine is stronger with the JDM ecu so its shifting higher? i dont know a whole lot about automatics

I know enough to be dangerous. I swapped in a Ford 4R70W into my 1965 mustang several years ago, and as that transmission requires a TCU, I had to buy, install, and program one that had been designed for my application. The transmission needs to know throttle position and vehicle speed in order to know when and how hard to shift. On a car with an ECU (which the old mustang didn't have originally), the ECU needs to know what gear the car is in, if it's in park or neutral (to enable the starter) from the TCS and maybe some other thing. Point is...while the TCS does control the transmission, it and the ECU do share some information to make stuff work right.

Last night after the latest tune, I did drive it with the AT OIL light blinking, and it was slipping terribly at any shift above half throttle. Obviously the TCU had no idea what the throttle position was and couldn't increase line pressure in the transmission to get it clamped into gear.

Sounds like I know a lot? Well I'm old and I fix things...so I've had to learn a lot....but this is the first time I've ever had to reflash any car. In the past, about all I've ever had to do is take my car to the dyno and tell the guy to make it go faster. The learning curve on this stuff is steep.

Phil

i looked at the wiring diagram and it looks like the TPS is wired in parallel with the ECU and TCM. the ecu does not send a TPS value to the TCM. they both just read the same sensor. just like the gauge cluster and ECU both read the VSS and coolant temperature sensor in parallel. each will work without the other and they dont actually communicate. the 16 bit subaru are very simple. the CAN bus ones talk to each other more. i dont think the ECU is self is the issue. it might have a bad connection or something.

If these tunes don't fix it...I'm buying another ECU.

The kid is driving the car right now on the USDM ECU and it has no problems. Maybe the JDM ECU just has a problem or is missing something critical to the function of the transmission.

It's not that it can't read the throttle position though, because that shows up in the logs. I found a seller with the right ECU for a JDM WRX auto AND the TCS from the same car. If those 2 won't talk to each other...than I guess that will tell me something. This little experiment is going to set me back another 4 bills though.

Phil

I still wonder if the ecu is damaged. Have you opened it to look at the circuit board and make sure there is no visible damage? Stranger things have happened

No, I have not...but I have ordered another ECU as of about 2 minutes ago.

For now the car is running "OK". I programmed out the blow-by-sensor code and then noticed a second code for front O2 sensor...that was an actual problem. We'd pinched one of the wires in two trying to get the engine in. I swapped in the sensor from our old engine and fixed that.

My current plan is to get the slightly newer JDM ECU in and see if that fixes it. If that doesn't fix it, try to swap in the matching TCU which I'm also buying. My internet research indicates the bracket is different...so it really won't mount right...but if it WORKS...I can figure out a way to mount it.

If none of that works, I'm going to get the existing USDM ECU tuned and call it good for now.

By the way, I appreciate all you guys reading these posts and the responses as well. It really helps to be able to bounce this sort of thing of the board. If nothing else, seeing a few hundred reads and no one jumping in and saying "You're missing the obvious. Fix A or B or whatever" lets me know that whatever the problem is...it's not something simple likely.

Phil

Simple would be nice honestly. I'm almost at a completely new car at this point but the flip side is I don't need a new car for a while now and I have a better body style then the newer ones imo. Good luck with everything

My understanding, FWIW, is AT vs. MT is a wire jumper, not a software/firmware/map issue.
When swapping type of trans, you need to add or delete a wire going to the ECU.

Conversions or trans section will likely yield the answer, I have seen it come up a few times before.

Yeah....but...

I didn't do a MT to AT swap. If the ground you're speaking of is accomplished via the car's wiring harness, it should already exist (or not exist) and the ECU would pick up on it as soon as it was plugged into the existing harness.

I'm still waiting on the replacement JDM ECU and matching TCU. Per the tracking it will be here tomorrow. Damn, I hope this works. If it doesn't fix the communications issue...I'll be out of ideas.

Phil

Well,

That didn't work.

The 2004 JDM ECU started the engine up, but it had the same flashing AT light and wouldn't shift right. So I moved over to swap the TCU and here's what I found:

JDM Transmission Control Module LEFT - USDM Transmission Control Module RIGHT



The plug isn't even the same. The JDM TCU is plastic cased and smaller. It looks completely different.

So...I'm bagging the whole JDM and the whole AVCS idea and will get the USDM ECU tuned best I can.

I'm giving up on this whole thing for now. If anyone knows of a way to AVCS working in a 2004 WRX with an automatic, please let me know how...because I'll be darned if I can figure it out.

Phil

Just a final-final update on this project, for anyone searching in the future.

We were able to finish the swap and get the engine tuned via e-tuning with iatuning, however, we were not able to find any solution that allowed us to use either of the jdm ecu's I was able to get. So, the car is running with no avcs functionality.

AND...it runs pretty well that way actually. If you are reading this and considering purchasing one of the JDM EJ205's out there...I would highly recommend JDM Racing engines as a supplier. I got a quality engine, and I have run a compression test and verified their results.

However, if you have a 4EAT, you should NOT attempt to get the AVCS functioning. Do NOT buy a wiring harness to hook it up. DO NOT pay extra for the JDM ECU...as that is all wasted money with a 4EAT (at least on a 2004 WRX).

DO...carefully look over the new engine and replace anything that looks rough. A timing belt on a 50,000 mile engine that is 15 years old is likely ready for replacement due to age at this point, regardless of miles...and for Gosh sakes, buy a new set of iridium spark plugs. I lost more sleep chasing misfires because I had swapped over a set of copper plugs from the old engine...that ONLY HAD 1000 MILES ON THEM. Finally replaced the plugs and all my issues went away.

Also DO plug your avcs holes in the cams and swap over your USDM cam gears before you install the engine.

I think that's about it. Final story.

2004 WRX 5MT AVCS = Good.
2004 WRX 4EAT AVCS = Impossible.

Phil

Almost 2 years ago I hooked up a JDM ecu to my swap, moved the TGV wires over on the stock harness for AVCS to run the JDM ECU, and got it tuned. The "At oil temp" light has been constantly flashing since day one, DTC 38. I ignored it (because I'm stupid) and the trans failed about 6 months after

Just got the new trans in and went through the procedure per the manual for the code, which ends in "replace the ECM"

Stumbled upon this:
https://www.drive2.com/l/10009348/

It's in Russian, but basically the JDM ECU for the AT model just doesn't have the Torque control signals needed to communicate with the TCU. There's no remedy for this that I can see. You'll just eat through your clutch packs until the valve body is clogged and it won't shift.

The first trans lasted about 6 months for me probably because I already had a valve body kit installed so the faster shifting was compensating a bit.

Good info. Update as of 2022 still have not found any solution that allows AVCS functionality with 4EAT on a 2004 WRX.

What is the AT ECU CODE AND AUTO TRANSMISSION CODE