My idle has been a little off ever since I did my B18B swap in October (about 1100 rpm). I've checked most everything except for the ignition timing, so I'm doing that now. When I initially put the engine in and tried to fix the idle being too high, I used the idle adjust screw on the TB (and went through the correct procedure such as unplugging the IACV) and kept turning it in until it got down to spec. I have it screwed all the way in and my idle got down to 1100 rpm. I've been going over the steps for checking and adjusting the ignition timing, and it says it should be at 16° when the engine is at 750 rpm. If I can't get it down to 750 to initially check the timing, should it still be set to 16°, or something different for 1100 rpm?

 

The ignition timing being slightly off shouldn't affect idle speed, something else is off.

 

it's only going to affect idle speed a little, not much

you have a vacuum leak of some sort, you can use a spray bottle of water that has a very fine mist setting to spray around the intake area and try to find the leak, could be the intake manifold gasket or even a vacuum hose that has a small crack, when the idle changes then you found a leak

 

I suspected a vacuum leak because when I did the engine swap, I put all new EVERYTHING on the intake side of the engine. O-rings, vacuum lines, gaskets, etc. So I got a smoke test done at a shop and they said it was perfect, no vacuum leaks anywhere. Anyway, tomorrow I'm going to pull the IACV and adjust idle screw on the TB so I can temporarily get 750 rpm and then I'll check my ignition timing. The motor runs pretty solid, sounds good, and I know my timing belt and everything on that side of the engine is good. Valve clearences are in spec. Any ideas? I've also noticed there's a small adjustment screw on the IACV itself that an allen wrench could go into. Does that do anything?

 

no, just leave that alone, you can try checking base idle, unplug the iacv so it drops down, it should get to 500-600 rpms, if not you can use a flathead screwdriver to try to adjust it, but make a mark first so you know where it originally was, that way if you can't get it down to 550 or so then you can put it back...if you can't get it down to 550 then you have a vacuum leak...if you can get it to 550 then it should be fixed

plug the iacv back in and see how it idles

 

I've messed with the base idle many times, but it never goes below 650. And according to the Helms manual, it's supposed to be 480 rpm before you plug the iacv back in. I'm nearly positive there's no vacuum leak though because like I said, I had a shop do a smoke test on the intake and there weren't any leaks. Plus I've checked myself by spraying around everything and haven't gotten the idle to fluctuate at all. Anyway, I adjusted the ignition timing a little bit to get it right on 16 BTDC at 750 rpm. My idle isn't fluctuating, it just sits steady right at 1100...