I bought a 90 civic DX about a week ago and the guy who sold it to me said that the old harness was messed up so he took it out and tried to install a SI harness...he said he would get the car to crank over but now it doesn't do anything...I get power to my headlights and interior lights but I get nothing to the motor...its a D16A6 MPFI on a PM6...is there a way for me to rewire the harness to make it work? Or what am Imissing?

 

You MUST use a DX harness and convert it to fit the A6 motor.
You will need to add a couple wires and such for the extra injectors and sensor in the distributor.
Search for DPFI to MPFI for the conversion details.

Using the Si harness will not work because your cabin harness is wired for the DPFI harness.
Wires are missing and are in the wrong place on the connectors.

If you really feel the need to use the Si harness, then you need to swap out your cabin harness as well.
Very much not worth the effort.

 

Yeah but the car already came with a MPFI...does that make a difference?

 

The engine is MPFI meaning that it has 4 injectors rather than the 2 injectors that the DX came with.
The stock DX car is DPFI as it did not come with MPFI.

There are 2 harnesses to be concerned with.
Engine harness - Plugs into all the sensors on the engine and ends at a couple large connectors at the firewall.
Dash harness -Receives the large connectors at the firewall and goes to the ECU, cluster, main relay, etc.
You can NOT mix and match a DPFI and MPFI engine harnesses and dash harness.
They may look similar, but the wires in the firewall connectors are different.
It simply will NOT work!

It is not impossible to install a complete Si harness.
The only time is remotely makes sense is when you don't have an engine in the car and your dash is completely removed.
Then you can swap out the engine harness as well as the dash harness together.
It would still be easier to just convert the DPFI harness!

It is also not impossible to use a stock Si engine harness and modify the DPFI dash harness.
It would be a complete wiring NIGHTMARE and totally not worth it in any way.

So, IF the guy you got it from put the Si engine harness on the motor then he would have to do some big wiring changes to the cabin harness.
If he STARTED to do these changes, then you are FORKED because it will be a nightmare tracing whatever work he may have done so far.

IF he simply put the Si engine harness on, and plugged it in, and did NOT tamper with the cabin harness, then there is still hope.
Just get an unmolested DX engine harness and do the DPFI to MPFI conversion and you are set.

 

Your interior cabin is still running DX while you are trying to run SI stuff in the engine bay. It won't want to work together.

So get started on the DX harness and convert it to MPFI to run your engine. Skip the SI harness and use it for parts.