I bought a eg hatch that was B20vtec swapped with a b20b block and b16 head. Long story short that motor blew up. Now I have a b20z block with the b16 head. The problem is it’s running super rough and sometimes idle surges. It’ll idle at 1,000 to 1,100 rpms but it’s just super rough and the motor shakes. I do have new injectors which to my knowledge they are the same. I did also calibrate a new tps sensor, ive done two different iacvs. The only difference between this engine build and the last (to my knowledge) is the block is a b20z instead of a b20b, and the head has new valve springs/keppers. Ive double checked the timing too and it looks all good. I’m starting to think it’s something to do with the tune. I’ve tried to download the tune onto a computer to look at it but it’s always just said error. Would I need a retune for it to run right? I did drive it around the block and it was just super rough and hesitating. Please help

 

Yes, you WILL need a re-tune. Now, this assumes that all is well with the engine itself. Rough running at idle typically means that a cylinder or two isn't firing... so have you done a compression test on all four cylinders ? If not, have you pulled one spark plug wire at a time while the engine is idling to see which cylinder(s) make no audible change in how the engine runs ?

If not, you have some testing to do.