Rep Power: 0

Good day all I swapped the motor in my Civic and now my RPM hunts from 1200-2600ish.

I've replaced the IACV, TPS, PCV,and MAP sensors so far. Checked for Vacuum leaks and check the rad for air lock.

The codes I have are P505 Idle air control system and P1505 PCV air leakage.

My background is a Aviation Technician and my neighbour is currently a automotive mechanic, We spent 5 hours in the shop today with no luck. This is has been on going since I changed motors 2 weeks ago.

We have metered the sensors back to the ECU and everything checks out.
I really need the car back on the road, I can't afford the dealership so any new ideas would be great.

I can't afford the dealership

2003 Civic DX, 1.7 Motor everything is stock. 5 speed Manual

Here is a Video link [autostream]http://autostream.com/ibcivicforums/?page_type=firebirdplayerthumbnail&framepage=1443& transactionid=1380491169-156347921&posted_by=_www.civicforums.com&youtube_v ideo_id=7WAC4mOtjho[/autostream]

 
Rep Power: 0

Is this idle relearn a real procedure I couldn't find it in my manual and it didn't work for me??

 
Rep Power: 518

That doesn't seem quite like the average vacuum leak..... Make sure the throttle and cruise cables are not holding the throttle open.


Remove air filter cover and leave off, start engine.
Use your finger to plug off the port for the IAC valve, it's visible in the throttle body.

What happens?
Does that stop the surge?
Does it slow it down at all?
Did it kill the engine?


Did the engine come with the intake manifold, did you use it?
Or did you swap all external parts from the old engine?
(Intake is plastic, could have been cracked or broken at the auto recycle yard)

 
Rep Power: 0

The air filter cover is off, surge continues even when plugged, doesn't seem to slow down much. Doesn't kill the engine. I used the intake and manifold and throttle body off my original engine which had no issues, other than I spun a rod bearing. I've already replaced that sensor with a brand new one. No change, tried new map and tps.

 
Rep Power: 518

Ok so that kinda rules out the IAC being wide open, so it probably has a large vacuum leak. Big enough to make a wrong sounding loud sucking sound.

Typical stuff might include
PCV valve
PCV hoses
EVAP purge hose
Brake booster hose
Any other vacuum hoses
Intake manifold
Throttle body

And since you just had everything all apart, inspect everything you touched, gaskets and all.

 
Rep Power: 179

The only time I saw something like that is when my 90 Honda accord fast idle valve was bad.

How's is your coolant? Did you try unplugging the IACV connector and see what happens.


See attachment for other troubleshooting. You can download the service manual as well.


Idle Control System Diagram
The idle speed of the engine is controlled by the Idle Air Control (IAC) valve:
After the engine starts, the IAC valve opens for a certain amount of time.

The amount of air is increased to raise the idle speed.
When the engine coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount of bypassed air is thus controlled in relation to engine coolant temperature.