Can I put a 91 hf engine harness on 90 si hatch, and vise versa. I know the hf has a egr and the si dont but besides that are the pin locations the same. I sold my hf harness to a guy with a si and he s having problems so I just want to double check that this isnt the problem. Plus I plan on swapping the si harness on my new hf because I rebuilt the whole harness from sracth with all the vtec wires incorperatid with it with factory plugs , so it looks stock.

 

hf and si harnesses are wired the same. you will have 1 extra wire w/ the hf harness that goes to something not important. about the equivilant of the tandem valve of a standard hatch.

 

Yeah, and one plug short as well.
The Si has something on the back of the intake manifold the HF doesn't have.
The HF has a EGR (Exhaust Gas Recirculation) valve that he Si doesn't have.

 

i can show you my egr on my si

 

There shouldn't be any problems. I put my 91 Si ECU on my 88 HF to move it around. No problems at all, no light even after warm up mode shut down. HF motor likes fuel

 

No, they are different.

brian g

 

would u like to shed some light to that statement brian??
manny

 

 

Update...... I gave the kid a si harness and he swapped it out for the hf one and the car fired right up so i guess it wont work. however I will find out which pins are different and try to swap them around to make it work eventually.

 

i can post wire diagrams to prove that everyting important in the operation of the car is identical with the hf and si harness