BP5A ECU
 

Out of curiosity, does anyone know if our US cars could swap the BP4W to the BP5A ECU?

I ask because I'm in an OBDII emissions county and know that the BP5A did not have an EGR, so the possibility of finding an ECU that would allow me to delete the EGR and stay legal would be quite convenient.

Thanks!

Do they require that the vin stored in the computer matches the chassis?

They might, but I'm sure it could be argued that a bad ECU had been swapped out. Not 100% sure on this though.

Does the Miata NB ECU even have an internal VIN tag?

I see where you are going with the BP5A ECU. It might be nice to have a factory ECU that's better matched to the hardware... I've got a squaretop and a 5A cam, I wonder if the 4W brain leaves anything on the table compared to the 5A. If you have a source, I might be interested.

Off the top of my head, pinouts may also be different so may not be 100% PnP. Revenant would probably be a good person to ask about this.

Any update/follow-up on this?

Also curious to know the answer.

I know I've read about the Spec Miata guys swapping around stock ECUs to get an extra 3-4hp here and there on the dyno. I don't know if that's within the deviation on the dyno or some sort of deviation in the ECU itself, or maybe mental damage withing the SM community? Either way, there is somewhat of a precedent for it.

I think the NB has a vin tag that the machine see's. I cant remember 100%, but I think it pop'd up on the smog machine and there's a good possibility that the tech checked my vin on the dash.

Seems like if this is true, only CARB-legal way to replace a dead ECU is to get a new one with VIN burned in. curious to know if this is the case. I know there's some smog techs and experts over at m.net - might be worth asking this question over there.

IIRC, I believe the VIN data comes from the state. The first step for the tech is scanning the code (or entering the man readable code for older machines) on the form the DMV sent you. The machine then calls home to Sac and pulls down relevant info, including the VIN. I believe tech then confirms via visual.

But you are right, this is an m.net question fer sure.

Well they are certainly not going to swap right over. The location, wiring, and harness are not the same.

But perhaps you could completely custom re-wire it to work. I can't confirm or deny if that's possible. Doubt it.

The BP4W/Y and BP5A have the same connector. I am betting that it will swap right in. According to some threads at mx5nutz, BP5A is the only [non-US market] NB1 ECU that does not require an immobilizer. It should also have a 7500RPM redline, not use the EGR system, and have slightly better tuning for higher-flow intake/exhaust.

BP5A:

https://www.miataturbo.net/attachmen...ine=1372091069

BP4Y:

https://www.miataturbo.net/attachmen...ine=1372091069

Really? Wow my mistake then. I vaguely remember comparing the harnesses a long time ago and not arriving at the same conclusion.

*EDIT: did I go full retard and confuse bp5a with bp05? I think so. Nevermind

Did any of you buy this one that was up on ebay earlier this month?

Mazda Miata ECU BP5A for 1999 2000 Engine Control Unit | eBay

Out of curiosity/stupidity I ordered a BP5A ECU today, I'll let you guys know if it works when it arrives next week.

Ordered from where? YAJ?
I should be getting mine on Monday, but probably wont be able to try it for a while.

I look forward to your findings!

Mine arrived today. I also have a BP4W(49-state) and BP4Y (CA) to compare. WBO2 is installed, but I dont know if I'll have time to test it out any time soon.

https://www.miataturbo.net/attachmen...ine=1373925566

Some other fun parts arrived as well ;)

https://www.miataturbo.net/attachmen...ine=1373925566

Those appear to actually have EGR nipples on them :squint: Now I really want one.

Yeah, theyre actually UK-spec manifolds with EGR fittings. It took a long time but managed to build 2 complete sets of manifold, downpipe, and heatshield with each type of 4->2 header.

If youre actually interested, PM me and I can tell you how I managed to get all the parts.

IT WORKS!


I was going to put it in tomorrow after work but it's so god dam hot during daylight that I figured I'd give it a shot in the dark since it's a bit cooler here at 11:30 at night :)


Started right up, since it's dark I noticed that the check engine light is constantly on but juuuuust barely, there's no way you'd be able to see it during the day but in the pitch black of night you can just barely see that it's ever so slightly lit up which is odd.

It's definitely got a different tune, I only drove it around for 5 or 10 minutes but the first thing I noticed is that the revs don't drop as quickly and it idles at around 1,500 when you're coming to a stop, hangs there for a second, and then comes down to where it should be.

There's definitely a higher rev limit, according to the tach it's not quite 7,500 probably closer to 7,400 or 7,300 but who knows how accurate the OEM tch is and it's definitely higher than before so that's pretty cool.

Power feels about the same but again I only drove it for a very short period of time so I'll know more tomorrow after I can spend some more time in it.


I just sorta stuffed it up under the dash so that I can swap back and forth between it and the regular ECU to get some back to back comparisons and I'm scheduling dyno time soon to have the Greddy E-Manage tuned so maybe I'll even get some head to head numbers between the two ECU's, I'm curious as hell :)


I got mine from JDM Engine Depot

So Ciotti, any updates? Also interested if this was installed in a CA Emissions car or a 49 state car, and what PN ECU you used.

Other than the RB header, are you running a 5A cam or squaretop on your 99? I'm curious to see what the wideband says. Also, were you able to scan that CEL?

Sorry for bringing up an old thread, but instead of starting a new one I'll just add my experience. I just recently did a bp5a swap and currently running the bp5a ecu also. To better represent the jdm layouts I have converted my returnless fuel system to a true fuel return system using an na8 fuel feed line. From there I followed a diy link on miata turbo.net and have a successful fuel return system running the jdm 60psi fpr.

Motor jdm bp5a motor has the provisions for egr and egr tube. They are just blocked off and not used. The bp5a also came with a working vics system. From driving I can say the cold tune is different and top end pull is much more fulfilling versus the bp4y ecu. Currently only mod is a rb 4-1 header and custom rear muffler section. I do however have a lot of afterfire ... On throttle release and in between shifts. So far no issues and the pin outs seems correct. Please don't quote me on in-depth details as I have only been able to drive the vehicle about 40 miles , and then my fm pressure plate gave up on me. As far as the jdm ecu working I can a say that it will be a pnp in our us spec nb1.

NB1 and NB2 cars are being broken left right and centre in the UK due to chronic rust - if you guys in the states are after parts then UK ebay, breakers, making contact on UK forums would be a good way to go. Parts are generally cheap too (Unlike rest of Europe etc) as old cars have very little value.

Holy crap, I thought we had bad rust in new england, I guess the rust is worse in old england Most NBs I see arent even as rusty as my and I think I've seen a total of 1 rusted out bad enough that I would think about just parting it out and scrapping it because its unsafe (and that was an MSM, too bad he wanted 5k). I guess maybe the UK NBs didnt get the enhanced rust proofing that they did in the states.