Anyway to get OBDII working with a JDM swap?

[twistedsymphony]

So the headgaskets went in my 98 LGT and I'm consider just swapping the motor. If I'm going to go through the effort I'd like to upgrade. I'd love an STi EJ257 but I can't swing the $5K for just the motor that I see them going for.

I've noticed that JDM motors seem far more plentiful and lower cost than any of the USDM motor sets. however I'm in NH and we have to have an annual OBDII plugin check for emissions. Are there USDM comptuers that are compatible with certain model JDM engines to make this work, or other things I can do to pass emissions?

cliff notes: is there something I can do to get a JDM engine to pass ODBII or should I just stick to USDM only stuff?

[Yamazaki]

My OBD2 reader works on the S401... It shows the engine codes properly anyway.

[rkrenicki]

3rd gen and up JDM engine are OBD-II.

If you are looking to stick with 2nd gen stuff, then no. There is no native OBD-II capable ECU for turbo engines like the EJ20H or EJ20R. Perhaps if you use an OBD ready aftermarket ECU, but that is a whole lot of work. If you are talking about a Japanese EJ25D (From a Grand Wagon or 1997 Lancaster), then you would likely be able to use a US EJ25D ECU on it, but that is purely speculation.

[twistedsymphony]

I've heard that while 03 and new Japanese motors are "OBDII" they don't pass inspection because they use a version of the protocol that doesn't work with the scan equipment... I honestly don't know how much truth there is to that but I've heard it from two different people who work in inspection shops.

I'm not thinking of any motor in particular... mostly just anything reliable and affordable in a 2.0T or 2.5T

[chuckthefuk]

twisted is correct. yes JDM OBD2 can read codes and clear them but they do not communicate real time data which is what new inspections require such as rpm and such. no work around currently besides parallel ecus

[lord flashheart]

twisted is correct. yes JDM OBD2 can read codes and clear them but they do not communicate real time data which is what new inspections require such as rpm and such. no work around currently besides parallel ecus
This is exactly why I purchased a 95. Its the only BD legacy to get the tail pipe test. OBD1 is much easier to manipulate/cheat.


OP, you can make fantastic STi level power without a full swap. You could get a JDM engine from the same era, run it with your engine management and use a piggyback to dial it in. That's basically what I did on my car. Except I couldn't afford a piggyback so I swapped to the stock injectors. It ran pretty good on par with a stock EJ205.
Anothernord put a turbo set up on his EJ25D and iirc he was well over what a stock STi will put down. Like 320whp.

[Blayzed]

I also live in NH and have a JDM EJ25D in my '99 LGT. I'm running the stock ecu and have had 0 problems with the OBDII, but if your set on turbo you'll def need to do some swappin. Also, shops can get away with not plugging in your car since it's more than 15 years old. It's not a written rule, but there are many shops that will let it slide. Worst case you could also run the ol' peel nd stick off another car or find an inspector that will let you plug in a "donor".

[thenines']

I also live in NH and have a JDM EJ25D in my '99 LGT. I'm running the stock ecu and have had 0 problems with the OBDII, but if your set on turbo you'll def need to do some swappin. Also, shops can get away with not plugging in your car since it's more than 15 years old. It's not a written rule, but there are many shops that will let it slide. Worst case you could also run the ol' peel nd stick off another car or find an inspector that will let you plug in a "donor". Good thing you don't live in mass-sets off a red flag if you scan one car (the VIN) and plugged in a donor car

[Blayzed]

^^... we're too busy livin free or dying up here to worry about minor details like VINs =P

[meepers]

Your only real options are Phase 1 OBD2 and piggy back, or Phase 2 with WRX wiring merge. Both routes require some wiring know how. Neither is impossible or really even difficult. It is more time consuming then anything. My 98 Leggy passed AZ inspection/scan running ej255 short block, EJ25d massaged heads, 550 injectors, and Emanage ultimate. As long as you dont live in the socialist republic of cali, you should be fine!

I would recommend doing a phase 2 WRX harness and tuning with opensource/tactrix/accessport whatever, as it gives you more options down the road.

[rkrenicki]

twisted is correct. yes JDM OBD2 can read codes and clear them but they do not communicate real time data which is what new inspections require such as rpm and such. no work around currently besides parallel ecus

Really? When I had my tactrix openport connected to Yama's S401, I was getting various status data like RPMs and temperatures. I did not look for Emissions readyness (which it likely does not have) and I did not look at all of the diagnostic PIDs, but the basic stuff was there.

I will give it another look when I go down there next.

[twistedsymphony]

I also live in NH and have a JDM EJ25D in my '99 LGT. I'm running the stock ecu and have had 0 problems with the OBDII, but if your set on turbo you'll def need to do some swappin. Also, shops can get away with not plugging in your car since it's more than 15 years old. It's not a written rule, but there are many shops that will let it slide. Worst case you could also run the ol' peel nd stick off another car or find an inspector that will let you plug in a "donor".

yeah, I've played the inspection game before with other cars that I've owned... it gets old year after. I have a LS1 swapped Nissan 240sx that is now 100% legal and can be run at any shop. The Legacy is more a daily driver so I'm not looking for a monster build but rather something that makes good power and will be reliable on a mostly stock motor, and none of the headaches that come from a highly modified car.

[Dead91silvia]

Interesting... I actually just had my JDM Legacy tested as an OBDI car, even thought for the year it's meant to be tested as an OBDII. I guess it depends on the state you are in.

[vinylscratchp0n3]

Could a third gen GT-B swap into a second gen be OBDII compatible? It's the same engine from a second gen GT-B, but if third gens are OBDII, it should work.

[elislider]

OP, you can run a v5/6 EJ207 STi motor on USDM WRX electronics if you run the JDM EJ207 longblock and all WRX intake/wiring/sensors/ECU, then tune with open source or AccessPort


This is exactly why I purchased a 95. Its the only BD legacy to get the tail pipe test. OBD1 is much easier to manipulate/cheat.
well, OBD1 is easier to run whatever *electronics* you want and still pass as long as your motor can pass a sniffer test. example: run a stock cat or lean out your tune and you'll probably pass.
OBD2 is way easier to pass with any motor you want regardless of how its running, as long as you have a tuneable ECU (usdm wrx/sti, etc) because you just delete the codes or force readiness and their computer will just say "you're ok".

[chuckthefuk]

Really? When I had my tactrix openport connected to Yama's S401, I was getting various status data like RPMs and temperatures. I did not look for Emissions readyness (which it likely does not have) and I did not look at all of the diagnostic PIDs, but the basic stuff was there.

I will give it another look when I go down there next.

I know this is a year later but just wanted to chime in on this. The reason Tactrix and Learning View or another logger can see the values is the Japanese protocol is present in the software you are using so communication is not an issue. Similar to Open Source tuning a JDM 16 or 32 bit ECU.

[chuckthefuk]

Your only real options are Phase 1 OBD2 and piggy back, or Phase 2 with WRX wiring merge. Both routes require some wiring know how. Neither is impossible or really even difficult. It is more time consuming then anything. My 98 Leggy passed AZ inspection/scan running ej255 short block, EJ25d massaged heads, 550 injectors, and Emanage ultimate. As long as you dont live in the socialist republic of cali, you should be fine!

I would recommend doing a phase 2 WRX harness and tuning with opensource/tactrix/accessport whatever, as it gives you more options down the road.



The Phase 2 method you mentioned is becoming the standard for converting OBD1 to OBD2. This is much easier to achieve on the EJ205 or EJ207 Phase 1 98-00 JDM GC types as the intake manifolds are direct swap with USDM 02-05 WRX and only requires cam and crank gear swap to match the 02-05 WRX ECU + Harness with the addition of coil-on-plug (COP) conversion also sourced from a 02-05 wrx which is very common as many used manifolds will come with the wiring harness (engine portion) still attached with all sensors (TPS/IACV/etc) . By no means is this a plug n play or weekend conversion for a novice but it has been done and does run well with a healthy tune.

For the EJ20G / EJ20K conversion this requires modification to either the manifold flanges or electronic USDM additions.

As stated this neither impossible or really even difficult it just requires time... patience and a good source for wiring diagrams and donor items.

-Chuckles

[rkrenicki]

I know this is a year later but just wanted to chime in on this. The reason Tactrix and Learning View or another logger can see the values is the Japanese protocol is present in the software you are using so communication is not an issue. Similar to Open Source tuning a JDM 16 or 32 bit ECU.

So, when I was down in Maryland on the weekend, I tried some of my diagnostic tools on the S401 to see what the results would be.

My $15 generic pocket scanner would read OBD-II codes and OBD Readiness on the K-line protocol. It supported Oxygen, O2 Heater, Fuel System, and Component monitoring. Catalyst and Evap report as "not supported".

The rest of my tools all read the car just fine. I tried my generic VAG cable with FreeSSM which gave me everything. I tried my Tactrix which gave me everything. And the Subaru SelectMonitor 2 with the North American 01-04 model year cartridge called out the car as a "2.0 Turbo" and "2002 ABS AWD MT", and all of its functions seemed to work as well. This was the most surprising bit, since the cartridge is labeled as North American.

I neglected to try my Scan Gauge II, but since everything all of the way down to the cheapest of the ebay knock off scanners worked.. I have no reason to think that it wouldnt work either.

I was downright surprised to see that OBD Readiness checks worked, the lack of support for Catalyst checks might prove to be a problem for some states but the fact that it reports as "not supported" instead of a fail or "not ready", is probably a good thing.

It is entirely possible that the S401 has more OBD-II support than earlier models as it was at the very end of the generation.. but based on this particular model, I see the same data with the same protocols as my US car, with the exception of the unsupported readiness tests, and of course the addition of turbo related data.

[duncanm]

It is entirely possible that the S401 has more OBD-II support than earlier models as it was at the very end of the generation.. but based on this particular model, I see the same data with the same protocols as my US car, with the exception of the unsupported readiness tests, and of course the addition of turbo related data.

Your JDM S401 (RevD) has the later denso ECU. Earlier Rev B-C Gen3 JDM cars are JECS ECU's and support less.