Hi

had my rx7 rebuilt with a new crate engine from Mazda along with street port
car has had full new wiring harness, fuse boxes, fuel pump, injectors, single turbo conversion along with modified engine loom, coil harness is also new, fuel pump has been hard wired and fuel lines checked, stand alone ecu (link g4x) has tried multiple sets of plugs and coils such ign1a and oem
all the grounds have been checked out and pass, alternator has also been changed.
issue is whenever turbo spools up the car starts misfiring only if the the trailing coils are connected with leading plugs connected it runs to redline fine
the builder has said he’s checked the timing of the engine and it’s all ok

any ideas Would be appreciated as running out of ideas

 

welcome aboard. how/where did u find a new crate engine from mazda? with all that new wiring, i'd start there and recheck everything. is the trailing ign setup correctly in the ecu? maybe something with the leading/trailing split. now i could be completely wrong on that last part but just throwing what i can think of out there.

 

If you have a Version 4 FD or newer the coil positions were changed and if you use the USDM FSM as a guide you may hook up the harness or plugs in the wrong order.

 

OEM harness or aftermarket?