Hello guys, ive done an bp5a engine swap on my 00 nb, the car was originally a 1.8 sport (BP5C) ecu, when the swap was done the original ecu was installed (bp5c) and its running fine, but of course i dont have the benefits of the bp5a, higher rev limiter, better tune, etc, i just installed the bp5a ecu and it ran for a literally sec and then cut out, it probably run on the left over fuel on the injectors/cylinder, and now it cranks and doesnt start, anyone have any clue on whats going on?
is the ecu chassi specific? does it have any kind of immobilizer?
and does anyone have the ecu pinout for both ecu to see if there is any difference betwin the two of them (the connector are the same)
Thanks, Alex
I’m a bit confused. A 2000 NB has the BP-4W engine so I assume BP5C and BP5A are two ECUs which both run BP-4W engines. Is that right?
If it’s a UK car then yes, it will have an immobiliser which is coded to its original ECU and won’t start with another. (Other world markets, I don’t know.)
Okay, I looked at my usual reference for ECUs (http://www.mx5bitz.co.uk/mx5/store.php) and I see they have BP5C ECUs for '98-'01 NBs, but no mention of BP5A. What model is the BP5A from?
The BP5A is the standalone ecu fitted to the Japanese Eunos Roadster 1.8, 1997 - 2000. No factory immobiliser and associated benefits.
I’ve sold a number of these I guess mainly to owners replacing their existing BP5A but I believe there is a way to fit this ecu to the UK/European spec MK2 1.8 with the BP5C/BP5D ecu as standard. This would give improvement and essentially bypass the factory immobiliser.
To begin with I believe the fuel pump pins on the ecu are reversed. This may be the only difference but not had the benefit of a technical descussion with someone that has successfully(in practice) fitted one of these to their MK2.
When I last looked into this, the Americans(miata.net) provided the most information but not enough for me to convince one of my BP5A buyers to chance his arm.
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The car is an UK car, I swapped the engine with a BP5A and I’ve been running around with the original ECU, this engine and ECU was imported from a JDM car.
As I said, the car run for a second and then died so I’m guessing is fuel related more than an immobilizer issue, as I can’t hear the fuel pump running when I put the ignition on.
So what @rhino666 said makes sense, but any of you got the wiring diagram and pinout of both ECU so I can compare them?
I appreciate it guys
I don’t have wiring info for a UK or JDM NB, but a '99 Miata is here: https://www.miataforumz.com/1990-200-Miata-Wiring/99sys.pdf
That might give some insight. So far as I know the Miata doesn’t have an immobiliser either so there’s a moderate chance it’s the same as the JDM BP5A. Its fuel pump relay is operated by grounding a light green wire on pin 3N. If the UK loom doesn’t have a light green wire there, that’ll be a big clue.
I see you’ve been asking for info over on miata.net. Further browsing there and on miataturbo.net confirms the BP5A ECU is a plug and play swap on '99-'00 Miatas*, so at least all the most necessary wires are the same. So it’s pretty much a certainty the fuel pump relay will be driven by pin 3N on the BP5A ECU.
*It seems their stock ECU is numbered BP4W (confusingly same as the engine) or BP4Y (for California).