Hello

I have a 99 Civic LX that has developed a stalling problem.

It only occurs when the vehicle is completely warmed up. What will happen is, when I stop at a red light, or drive-thru, etc, the idle will slowly drop from the normal 600-700 range until the engine stalls. It's happening on a regular basis now. The vehicle has 115k miles on it.

As I said, only happens when engine is completely warmed up (ie after driving on highway, etc)
Outside temperature has no effect
No modifications to the car
No check engine light
I changed the spark plugs about 20k miles ago (the wires may be original)
I changed the fuel filter about 5k miles ago (in an attempt to also cure a possibly related symptom, engine is hard to start when there is less than 1/8 tank of gas)

Also can anyone tell me what the acceptable resistance is for the spark plug wires for this engine? I can't find this spec anywhere!

thanks!
-Mike

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pike47 &raquo;</TD></TR><TR><TD CLASS="quote">Hello

I have a 99 Civic LX that has developed a stalling problem.

It only occurs when the vehicle is completely warmed up. What will happen is, when I stop at a red light, or drive-thru, etc, the idle will slowly drop from the normal 600-700 range until the engine stalls. It's happening on a regular basis now. The vehicle has 115k miles on it.
</TD></TR></TABLE>

Sounds like an Idle Air Control Valve problem to me.

 

It does sound like an idle air control valve, but check your coolant level, maybe turn up the idle, or it could possibly be a dirty injector as well.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GT30LSVTEC &raquo;</TD></TR><TR><TD CLASS="quote">It does sound like an idle air control valve, but check your coolant level, maybe turn up the idle, or it could possibly be a dirty injector as well.</TD></TR></TABLE>

Never mess with the idle screw until all other problems have been solved. It's a band-aid at best. You should almost never have to touch the idle screw.

 

Yes this does sound familiar.. I had an IAC valve go bad on a 92 Saturn SL2 once. If I recall it was a relatively inexpensive part.

Is there any way I can test the IAC valve?

thanks
-Mike

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pike47 &raquo;</TD></TR><TR><TD CLASS="quote">Is there any way I can test the IAC valve?

thanks
-Mike</TD></TR></TABLE>

Yes. Unplug the IACV at idle with a thoroughly warmed engine. The idle should drop to the base idle speed for your model, typically 550 to 625 RPM, and the engine should stay running. If it stalls the idle passageways could be dirty.

This test will trigger a CEL. You can pull the 'back-up' fuse for 10 seconds to clear it.

If you feel ambitious, try the test and post back with your results. Normally if it stalls, and you've cleaned the passageways, you would then adjust the base idle screw on the throttle body to achieve the base idle.

 

I've finally got around to trying this test. (...now that the temperature in NE Ohio is reasonable)

Every time I stopped on the way home from work today the engine stalled. When I got home, I unplugged the electrical connector to the IACV and as soon as I did so the idle jumped to about 1600 and stayed there. And of course the CEL came on (P1509 Idle Air Control Circuit). Upon plugging it back in, idle returned to the normal 600 then stalled after a bit.

I'm really beginning to suspect this part is the problem because I also noticed that when the engine is about to die, simply tapping the valve lightly with a screwdriver will temporarily "fix" the problem.

-Mike