Motor is surging inbetween 1,500 and 3,000 rpm only if your hold it steady inbetween there. it revs fine. just surges there. I have replaced. Spark plugs, spark plug wires, pcv valve, we set the timing at 16. so the timing is right. Its a 94 b18b obd2 wiring harness, obd 1 ecu. with a jumper harness for obd 2 to 1. its in a 1998 ek. we tried to put a obd2 comp on it to read what was wrong with it. but it wouldnt register to the ecu. so were having trouble reading codes.

 

iacv or fitv?
try searching those.

 

Check:
vacuum leak
bad IACV
TPS way off calibration

 

we had 2 iacv so we switched them and it didnt help. so we cleaned on, still didnt help. The fitv is a good question. The tube comming off the intake next to the bigger tube. the fitv tube. Where does it go to?

 

I have the fitv line, the smaller outlet next to the coolant outlet going to the thermo Housing. is this right

 

the fitv has a plate held on by two little philips screws pull that off and theres like a big screw thing that you can tighten up inside. it loosens up by itself and causes an internal vac leak.
had a b16 that would idle from 500 to 4500. **** it was annoying.

 

Easiest way to determine what's up is, put your hand over the entire throttle body with the car running and first off all see if it keeps running. Chances are, with surging to 3000 it just might. At that point, with your hand blocking what SHOULD be the motors only source of air, you'll be able to hear where your pulling air that you shouldn't be. During this time, if a friend blocks the throttle body, you can spray brake cleaner around at all your gasket surfaces, around injectors, etc. If the rpm drops suddenly when you spray an area with brake cleaner, you found the leak.

If you cover the throttle body and the car dies, then yay...you've narrowed it down to one of three things. At that point, restart the car and get it to operating temp. Block the lower hole on the inside of the bore of the throttle body with your finger (take intake off obviously). If it's sucking air with the motor at operating temp, the fitv is too loose or apart completely. If it's not sucking air, move the the hole above.

The hole on the upper left is the IACV hole. Put your finger over it, if the the car idles very low or dies, then the IACV is stuck opened. If you cover it and the idle only drops slightly, then the idle adjustment screw is your answer.