Help with engine swap.
 

Hi guys, first post here and although its not a turbo question, I do still need help from some MX5 masters.
Hi, not sure if this will make sense because I can't seem to word it in my head what I want to ask.

Basically I have 1.6 mk2 nb, with a blown engine which I then later replaced with a mk1 1.8 non vvt. However, the engine loom didn't fit with my mk2's speedo and rev clock wiring and also my ecu wiring. I have the injector loom from the 1.8 which I've plugged into the engine, but when I got hold of a mk2 engine loom which fit into my ecu (1.8) and my clocks, the part that came out the firewall into the engine bay didn't fit into my injector loom.

Basically I'm asking if I've made a massive mistake trying to mate a 1.8 mk1 engine into a mk2 car with a mk2 loom? I cant seem to figure out a solution in how I can link the engine with the wiring into the car.

Edit: the mk2 is a 2001 and the engine is from a 1998 mk1 if it helps, thanks.

I apologise if this doesn't make sense I'm happy to answer questions if anyone is willing to help, thanks

I’m confused, because you’re discussing an engine swap, but then having issues with your Speedo and tach? Are you pulling the harness from behind the dash and trying to replace it with the mk1 stuff? You shouldn’t be changing any electrical items, just the physical engine.

Sorry for confusion, its hard to put into words my exact problem. Inside the car is all the original wiring, I have changed the engine to the mk1 1.8 non vvt as I said. But I'm having trouble actually wiring that engine, to inside the car. The loom I have fits my ecu, it fits my speedo, tachy etc with a big blue plug that went in through the firewall into the car, but in the engine bay, that loom doesn't fit into the engine wiring, injectors, air box etc

yeah, that big plug plug, you shouldn't have removed that with your 1.6. Usually all sensors are unplugged in the engine bay, the harness is flopped to the side, and engine removed. You then remove the upper intake manifold half to access the injectors and remove the injector/coolant temp harness.

Is that harness still on your 1.6? Do you still have your 1.6? Swapping back to this, plus all cam, crank, MAF, O2, intake temp, and injectors is what you should do. If you can't, take some pictures of each individual harness plug you're having issues with so we can help you better.

Swapping a 1.6 to a 1.8 is like that old trick of pulling the table cloth out without disturbing the plates/cups/silverware, except you're also pulling a new table cloth in. The plates/cups/silverware are your electronics, they're not supposed to know anythings different underneath them.

Damn I did get rid of my 1.6 and the engine loom that came with it. Is it possible that if I can get hold of another 1.6 loom which feeds into the car(into that blue plug and into the ecu) that it'll plug straight into my engine. Bearing in mind that the engine I have now came with the small sub-loom which plugs into the injectors and other sensors. I honestly thought it was going be a straight swap.