the car is flashing a p0505 code and the idle is erratic
it bounces between 1800 and 2000 rpm 4 times a second
parts I have changed already
idle air control valve
throttle body
map sensor
throttle position sensor
intake gaskets
plenum gaskets
vtec assembly
oil pressure switch
knock sensor
ecm
none of these parts have changed the idle problem at all
same code
same issue
also none of these parts where used parts. all brand new
checked all vacuum hoses, no leaks
checked all harness's and connectors. all in prefect working order

 

Air in the coolant passages in the cylinder head?

 

I thought about that but I made sure to bleed the system from the thermostat housing
I am pretty sure I got all the air out

 

Disclaimer: I've only worked on a 2.3 liter engine of that vintage one time and even then, not with the cooling system.

The above disclaimer out of the way, it is my understanding the 2.3 liter engines of that era have a bolt/plug in the head for bleeding the coolant passages; the thermostat housing is too low for a complete bleed.

 

I will try to find that bleeding port and try that.
thank you

 

Cool, keep us posted.

 

No, the coolant air-bleed is on the T-stat. The 2 places that air will collect is at the T-stat and at the radiator cap.

The UPPER radiator hose, directly to the head, didn't have a bleed valve on the 1998 that I used to have. Air in that hose would easily come out to the radiator cap, unless the car was parked steep downhill.

 

Thanks for correcting me.

 

I checked the shop manual and this suggests problem could be the idle speed setting is incorrect.

There is a specific sequence of steps to diagnose the idle problem code P0505. My pdf manual can't be "copied/pasted" due to protections. Suggest a download manual for $22 from automanualsource.com. Perhaps one of other moderators can help.

good luck