Civic EG

well first off its not my car thats doing it its my friends ek coupe with a b18b1 swap with a pr4 obd1 ecu.

heres what ive done with no luck
cleaned the fiv
replaced the iacv
bleed the cooling system
replaced pcv
tried different ecu's (different pr4 and a obd2 ls ecu)
adjusted idle screw all the way in
checked thottle body
replaced throttle body gasket

i have no idea what is causing it and the only code it pulls is 41 main o2 sensor heater

There's no point in trying to diagnose a car with a bad o2 sensor since it tells the ecu how to run your engine. Replace the bad o2 sensor first

Is the idle constant or bouncing up/down? does it do it all the time?

Strait 3k

Could the throttle cable be too tight, keeping the throttle body open just a hair?

had the throttle cable completly off the tb and was still at 3k

would a bad intake mani gasket make it do it.

but it also gets really hot im not sure if thats part of the problem

any cracks in the throttle body or hows the thottle body gasket itself?

94EJ2 wrote:had the throttle cable completly off the tb and was still at 3k

would a bad intake mani gasket make it do it.

but it also gets really hot im not sure if thats part of the problem

u have a bad gasket or a bad vacume line

Thottle body gasket is new
Thottle body is good
I didn't see a bad vacum line