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Not too long ago my Toyota MR2 was having a weird problem. The car would be able to start, but after running for a while it would stall, and have very bad air fuel mixture, black smoke and all. After consulting with several owners, one suggested that I check for leaked capacitors on the ECU as that might be one of the causes.

Toyota MR2 ECU
ECU located at the rear boot

The ECU on second generation Toyota MR2, in this case a 1991 3S-GTE version, is located at the rear boot wall that is seperating the boot from the engine, just behind the carpet. You will need a Philip screw driver and if I remember correctly, a 9 or 10 mm wrench to undo the mounting.

Toyota MR2 ECU
look at the 3 connectors at the bottom of the ECU

There are 3 connecting sockets located at the bottom part of the ECU. You should be able to disconnect them without much effort. The 3 connectors are of different sizes, you can’t go wrong when putting the thing back together. Do note that you should always disconnect the car battery and properly ground yourself before diving into such endeavour.

Toyota MR2 ECU
the 3 connectors

The ECU consists of two PCB boards, take off the 2 screws connecting both and you will be able to expose the innerds. In my case, I did not find any leaking capacitors. The problem was later found out to be caused by a faulty airflow sensor.

Toyota MR2 ECU
the capacitors on the ECU

More technical info on MR2 can be found on this page, including the Engine error code and how to diagnose them.

Discuss : Toyota MR2 ECU removal

  1. The most interesting fact that today, i see same article:).
    Although I do not remember there may be a link to the source,
    but probably not – but your site look solid.

  2. my 1991 mr2 has no illuminating cel , I check the blub and replaced it with a good one, and still the same issue, can you guide me on how to go about this issytjank you

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