Ok, this has probably been touched on a few times so I am sorry in advance if I am making another thread that's already been done a thousand times.

A couple days ago I did the head gasket on the B20B I have in my teggy, old one was on the verge of popping its biscuit. So everything went smoothly, no leaks, seepage, etc. there is one thing that has stumped me since. On cold starts after about a minute, I get 4 codes all misfire related, P0303, P0301, P1300 and P1399. But if I clear the codes, drive around and ready the monitors, and shut it off and start it up warm its fine, no codes no nothing. Even during cold start I hear no misfiring, and the motor doesn't move as if there is a miss, it's super smooth.

I already ran another compression test, with the old head gasket it was 150 in cylinders 1,2,4 and 140 in cyl 3. with the new gasket its 180-185 across all 4.
My timing is bang on, distributor is in good working order, wires are okay, plugs are ok (they are irridium, not sure how much honda motors like em but it wasnt doing this before I took the thing apart to do the head gasket).and no air in my coolant.

So as it stands I am unsure of what is causing the cold start misfire codes.

Any of you have experience with this?

 

It could Possible be the ECT sensor.

 

Honestly I have know idea what caused it, but today it didn't trip any codes when I warmed it up this morning before work. I will see if it does it tomorrow but I hope that is the end of it.

 

How old is ur ignition coil and rotor? Try replacing them if it gives u trouble.