I have a 1996 Integra SE. I just swapped in a JDM '99 B20B from Hmotorsonline.com. For the install, I removed my old motor and transmission, pulled off the A/C pump, P/S pump, alternator, distributor, intake and exhaust manifolds, intake, transmission, and spark plug wires and installed them on the B20B. The only pieces I did not swap were some support brackets (identical) and the oil pump because I ran into difficulty removing it.

I replaced the intake and exhaust manifold gaskets, the oil pan gasket, and the head cover and spark plug gaskets. When removing the B20B intake manifold, there was a lot of residue left from the paper gasket. I removed about 85% of it, with the only remaining material being around the studs that hold the manifold on. I got that material as thin as possible with a razor blade. I also replaced the spark plugs and did a valve lash adjustment (.102mm on the intake, .176mm on the exhaust).

After the initial install, I was leaking coolant from the intake manifold because I did not use silicone around the coolant passages. I removed the manifold, siliconed the two coolant holes (on the manifold) and re-used my intake manifold gasket because it did not yet bond with either surface and appeared to be in new condition. There are no fluid leaks of any kind going on in the engine, and the oil, coolant and transmission fluid are all new.

Now, my problem:

As soon as it starts up, the RPMs steadily climb to 4500, then after approximately 10 seconds, drop to 2000, climb to 3000, drop to 2000, climb to 3000, etc.

A friend went through my Helms and checked all the vacuum connections and said that they are in order. I replaced the TPS and verified that the voltage coming from it is correct. I went through the Helms and verified that the IACV is working.

Anyone have any advice? What should I check next? I'm not getting any CELs (besides a P0141 that has been on my car for awhile; bad heater in O2 sensor 2). I'm completely out of ideas!!

 

It was the intake manifold. I took it off again, installed a new gasket and siliconed both sides (engine side and manifold side) around the intake and coolant ports, now I'm idling at 1500. It sounds like ---- and I'm throwing a code 65.

That's a failure in the secondary o2 sensor, which was already giving off another code before.

Now I'll have to do a compression test and maybe re-do the valve lash to see if that's the reason it sounds bad? It seriously sounds like metal clapping. My cousin-in-law originally heard it and told me that I screwed up the valve adjustment.