i have a 97 ek hatch. i recenly put a new motor in it.(d16y7stock) and it idles up and down unless u put it in drive.i cleaned out my iacv swaped my old one from my old manifold and the problem continues!!i dont know why it is doing this no vaccum leaks or clogged hoses/valves. the one thing i did figure out is that when i plug the vacuum hole on the iacv when the car is running it idles perfect. coes any one know what the problem could be. thanks

 

tps sensor could be bad .
you have a obd2 system goto autozone and have them run a scan on it because im pretty sure you have a cel on

 

I agree. The IACV is one suspect. As mentioned, are any codes being thrown? Is there battery voltage at the IACV connector with the key in ON(II)?

Is the coolant level low? Have you tried bleeding the cooling system?

 

i scanned my car and the only thing that came up was the iacv. even though it says thats the problem i don't know if it really is. i did recently flush the system but i know that it is bleed. would the tps make idle fluctuate?

 

What specific CEL code was retrieved? Was it P0505?

 

i cant remember it was a month or to ago

 

Go to AutoZone and have the code pulled again. Or do it yourself if you have an OBDII scan tool.

 

yes the tps sensor would also make idle go up and down but you said its been like a month that you got codes from ecu go do it again and let us know

 

4 sure good looking

 

You may just need to close the idle air screw on the throttle body (big flat-slot screw) some. Also check that the throttle cable goes slack when no one is pressing the gas pedal, so it is not holding the throttle plate open.