Just put my integra back together after it snapped the timing belt on my B18a. I put a B20 cylinder head on it and replaced all the parts i needed to replace. I got it running but it runs kind of lousy. It seems like its a misfire, but its not. I have spark at all 4 plugs and my compression is good. Firing order is correct. It seems to run ruff only at an idle. Im almost positive all my vaccum lines are hooked up. The only thing is that i cannot locate where the plug on the harness for the EGR valve is located. So it is not plugged in, although im not throwing a CEL if that would even give me a CEL. I checked my cams to make sure they were both at the correct location for TDC. Im kind of stumped. I was told if the EGR was stuck open, it could give me a ruff idle, so is it possible that it not being plugged in that could cause the problem? Or could i possibly have vaccum lines in the wrong place? If needed i can take some pics, just designate an area that needs to be looked at.

 

i recently had the same issue with my b18a... it turned out to be the vaccuum lines were not routed correctly so double check that. Also explain exactly what it is doing at idle to make it run rough. It could be air in the coolant lines or a IAC. If you explain what it is doing i can try to help.

 

Sounds like it has a misfire. But only at an idle. If i rev it up it sounds normal. After i rev it, the idle will drop very low, like maybe 500rpm. I know its not a misfire and my compression and timing are good. Ill double check my vaccum lines.

 

my 91 integra is doin the same thing!!!!! but mine has a b18b1 intake manifold with a bypassed FITV and some vacuum line relocation goin on. it idles rough and when i rev up its sounds fine but when let off the gas the rpms drop to like 500 and then go back to 1100. (cuz! thats where i like my idle!)