ok, I've searched about this, asked friends, co-workers, everything and still can't find the problem...

1993 prelude si, just swapped an H22A into it, since the swap, the idle has been surging from 900-1600rpm. when i start the car, it kinda has a hard time turning over but when it does, the idle chills at about 2000 until I give it some gas, then it'll drop down to about 900 and bounce between 900-1400. It doesnt matter how long I drive, it wont stop. I've tried cleaning out the IACV, didnt work, tried using my old IACV, still didnt stop. topped off the coolant, did nothing. changed the spark plugs, twice, nothing. the distributor is the same one I had on my old motor (h23) and it worked fine then so I know its good. anybody have any suggestions whats causing the idle problem and why its hard to get it to start???

 

You have a massive air leak somewhere...Check all vacuum hoses and vacuum points at the manifold. Make sure your TPS is set at .45 volts at idle and 4.5 volts at WOT. Remove the fast idle thermo valve (located on bottom of throttle body) and clean it out as well, or just replace it with the unit from your H23...Bleed the coolant system at the thermostat hosing to ensure that there is no air in the coolant system...

The best way to check for vacuum leaks is to put a gauge on it and make sure all readings are at proper specifications, or if you want to do it the old fashioned way, get a can of carb cleaner or brake cleaner and spray it on everything (do not get it near any painted surfaces).

Also, the air leak location that almost everyone overlooks is the throttle shaft. There is a seal in there that prevents air leaks, and if its damaged or dry rotted, then it will cause the same problems...

 

ok, I replaced the new IACV with the one from my H23 and that didnt work, so I cleaned out the FICV, no change. I took the throttle body off and the gasket was ripped right at the mass air flow sensor so I changed that, nothing at first, so I reset the ECU, ran it for like 2 minutes and it idled perfectly fine!! but now, it bumps the idle from 1200-1400 only until i rev it to about 4000 once or twice and then the idle settles at 1100-1200???

 

ok, now it only idles messed up until its warm, could it be the EGR?

 

when the car is cold it is supposed to idle at 1200-1500rpm depending on how cold it as, that's the IACV doing its job. Once your temp. gauge is halfway up (a warm engine) it should settle down to aound 750-800rpm, which is the normal idle for an H22 unless you've altered your idle screw.

 

nah, when i first start the car, the idle jumps up to about 2000, then after i give it a little gas in gear or somethin, the idle starts bouncing until the motor warms up, then itll settle to about 1000, sometimes when im sitting at red lights, itll randomly start bouncing again at random rpms, it never bounces over 2000 though.

 

Just wondering, did you bleed the coolant system or did you just top it off?

 

if the idle is adjusted too high or too low, it will also cause the jumping idle