My 2000 Accord with F23A1 engine blew a head gasket at 283,000 miles. I had the head checked for cracks, pressure tested, and milled to make sure its flat then put it back together with a Felpro head gasket. Now all seemed well until the engine warmed up and the idle speed jumped to about 2k. I shut it off and let it cool, checked the coolant and started it again...it idled great until it warmed up again. I drove it a few miles to see if it would clear up and it runs ok under a load but will sputter when I lift off the throttle and feels a bit sluggish. After the test drive it idles about 1200 to 1500 when in gear but stays steady somewhat steady. In park it surges rapidly from 800 to about 1200 rpm. I have not removed the IACV yet but wondered if that's the next step. A Honda mechanic thought it might just be air in the coolant lines but thought that would go away after driving a few miles. Suggestions?

 

do you have access to a vacuum gauge?
can you get the reading @idle

2500 rpm---

 

Warm "idle"....Vac fluctuates from 15 to 20 inches as idle fluctuates from 1000 rpm to 1700 rpm. :run: These speeds vary from day to day.

Steady 2500 rpm with a warm engine gives a steady 21 inches of Vac.

I have only driven about 20 miles since re-assembly if that helps with anything. Also... I sprayed some carb cleaner around the intake gasket and all the vacuum connections I could see from up top and I didn't notice any difference in idle or vac readings.

 

vacuum fluctuations at idle means you have a valvetrain problem.

between 17 to 21 inches of vacuum is what you should have at IDLE. and the gauge should be steady with no fluctuations whatsoever.


to pinpoint the problem, you can do the cylinder leakage test wherein you place the cylinders piston @ tdc and the you introduce regulated shop air into the cylinder.

might be a good idea to do a compression test

 

I just did a compression test on it with the engine warm. #1-175 #2-165 #3-170 #4-165
I also did an air hold on each cylinder with 125lbs of shop air. No sounds of leaking at all and no bubbles in the radiator.
I went out for a test drive after that and it seemed to run great....when I got back home and put it in park the idle started surging from 800 to about 1200 and when I put it back in drive or park the idle went to just a touch over 1000 and held steady.

When I had the head off I had removed a housing on the back of the head near the dist. It has 3 ports that go against the head that appear to be coolant passages, one had a semi-plugged screen that I cleaned while it was off. It also has what appears to be a solenoid..one wire to it, and what appears to be a temp sensor. I can't find its name in my haynes manual or find any pics of it online. Does it have anything to do with controlling idle?

 

check your iacv (idle air control valve) it might be going bad or might be clogged. that was the problem on my civic. do not spray anything on to it. the best way to test it is to let the car warm up and unplug it and see what happens

 

Ok....i removed the IACV this morning and cleaned it. Also reseated all the the connectors in that area. My wife drove it about 40 miles today and says it ran great!!
Mission accomplished....thanks so much for the help!
:yay: