So recently purchased an automatic 99 civic lx, car came with a d16y8 swap however they did not change the harness so it has the y7 harness and p2e ecu, therefore running fairly rough. I went and purchased a 98 ex p2p auto for the car, slightly bigger ecu but it plugged right in. Problem now is the car is turning over but won’t start and I noticed the fuel pump isn’t activating, my questions are now do I have to get the y8 harness? And does this new ecu have to be flashed to my car? Any help is appreciated fairly new to the Hondas!

 

Your ECU is not a "Plug-n-Play" computer swap... unless you have purchased an OBD-2B -> OBD-2A ECU conversion harness. Assuming you simply tried plugging in your new Y8 ECU, this is why the car won't start and the fuel pump doesn't get energized.

 

You know where I can get one of those?

 

Found one on Amazon but it has four input and only three output? Seem to only find them for manuals

 

It sounds like you have a few things going on with your Civic. First off, having a D16Y8 swap with a Y7 harness and P2E ECU can definitely cause running issues. However, swapping to a 98 EX P2P auto ECU should solve the problem, but it's strange that your fuel pump isn't activating.

To answer your questions, you don't necessarily have to get a Y8 harness, but it may make things easier in the long run. As for flashing the ECU, it's not always necessary but it's recommended to get the most out of your setup.

In regards to the fuel pump, there could be a few things causing it not to activate. Check the fuel pump relay and make sure it's functioning properly. Also, check for any loose or damaged wiring that could be preventing the pump from receiving power.

I hope this helps you out!

 

It is unlikely that you will find an automatic conversion harness. You will need a P2P ECU, but it MUST come from a '99-00 Civic EX. The '96-98 EX ECU will NOT work... even though it plugs in, the wiring order is totally different and this is why things are not functioning... like the fuel pump.