I am working on a 1997 Honda Civic Ex. 4 Cyl 1.6 liter. After the car runs fro about 5 minutes the engine starts surging up and down between 900 and 2100 RPM. When the engine is surging the CEL is not on. If I disconnect the Map sensor the edgine stops surging , but idles at about 1500 RPM and the check engine light comes on. The code that I get is P0141 which is an 02 sensor.

Any suggestions would be appreciated.

 

I would check all vacuum lines as a leak would make the idle surge, if there are no leaks possibly the iacv (intake air control valve) but I'm not 100% sure the civics have an iacv .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .ken &raquo;</TD></TR><TR><TD CLASS="quote">I would check all vacuum lines as a leak would make the idle surge, if there are no leaks possibly the iacv (intake air control valve) but I'm not 100% sure the civics have an iacv .</TD></TR></TABLE>

 

Also check the Throttle positioning Sensor. "TPS"

 

IACV. Remove it and clean it out with throttle plate cleaner. Make sure the wire mesh is free of crap.

 

I removed the throttle body and cleaned the IACV and the throttle body. The engine still surges. I also noticed that the car surges when the car is in gear and when the car is in reverse and brake pedal is depressed the engine idle smooths out at about 1200 RPM.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dakota11 &raquo;</TD></TR><TR><TD CLASS="quote">I removed the throttle body and cleaned the IACV and the throttle body. The engine still surges. I also noticed that the car surges when the car is in gear and when the car is in reverse and brake pedal is depressed the engine idle smooths out at about 1200 RPM. </TD></TR></TABLE>

Sounds like a vacuum leak.

A common place is the CC line at the back of the intake manifold, snoop around back there.