Hello guys I have an EJ9 , normally came as SFi with a d14a4/3 engine, we swapped it with a b16a2 engine from an ek4 98-00 model and running the stock engine harness and p2t ecu , we had an electrician fix the internal wiring basically to match everything up and everything worked flawlessly.
At some point during the breaking in period , the engine decided it does not like coolant anymore and the gasket went bye bye (it was due to the seller rebuild the engine poorly both money wise and technical side). A machine shop rebuild the engine we put it into the car and the first ride was fine , no engine errors no nothing just a small leak but it was quickly fixed.
the second ride a cel came up but a ride around the block and then the car sat.
an hour later I came to pick up the car and no cel no nothing , I was notified about that.
Today , I started my car in the morning and there it is , a glorious cel. after finding the plug , I extracted the code 54 , the car can pass 3k rpm , it does not bog down or anything , at very low speeds and low throttle it had some jerking (which wasn't normal) but after than that nothing in terms of driving.
CEL is constantly open , checked the wiring as much as I could didn't see anything out of the ordinary. CEL is persistent though.
I removed my battery for about a minute and a half and nothing.
What is your expertise on the matter , I might be able to use P30 to be exact. if my conversion harness is correct , but I don't think it has to do with the ecu. it seems so random..

Note the car was fired up after the rebuild yesterday. At the time of this post not even a full 24 hours has passed.
Also to note , the car has an acl oil pump and acl metals , higher cr. otherwise stock
Thank you for expertise!

 

So a quick update , it throws several CELs actually, 54 , 61 , 81 , I turned the engine off , removed the paper clip , started no CELs car is running like a dream!
Parked it for 2-3 hours , again the same a CEL , came back did the same thing with the paper clip again , worked removed the CEL , car is running smooth AF , 40~ minutes later back at the car CEL is actually turning off , turn the car back on , the CEL is back....
This car is haunted I swear.