2000 Honda Civic erratic idle

Hi JSG,

I would suggest cleaning the throttle body, idle adjust screw and IAC. Seems the idling system pasage is partially clogged resulting in inaccurate air flow and the low engine rpm.

The engine idling system is designed to compensate for load fluctuations and it should not work erratically. Idling should be constant at all times.

The fast idle is the IACV so you have already cleaned it. If symptoms are similar after leaning, the problem could be with the AC, if you have filled in freon, most probably you have overfilled it.

Refrigerant capacity is 21.1 - 22.9 ozs.
A pressure test would confrim if there is excessive pressure in the system.

Btw, is the Check engine light showing?

If the uneven idling is only with AC on, I would suggest checking the valve clearances. Tight clearances would cause the idling to drop before recovering when accelerator pedal is released.

Not the IACV but the valve lifters.

Are you doning the job yourself?

If the IAC and throttle body are confirmed to be ok, the most likely cause for the condition would be the valve clearances.

The labor time is quoted as 1.3 hours.
However during the work, there is a possibility of valve cover gaskets, plug seals and bushes needing replacement.

I asked if you are doing the job yourself because I can provide the necessary procedures but if you are not a technical person, this job is best done by professionals.

SINGLE OVERHEAD CAMSHAFT (SOHC)
Accord 2.3L & Civic
NOTE: Valves should be adjusted only when cylinder head temperature is
less than 100 °F (38 °C).
NOTE: On some applications, word "UP" is cast into camshaft pulley. On
other applications "UP" mark will be represented by an arrow pointing
to outer edge of camshaft pulley.

1. Remove timing belt upper cover, valve cover, spark plugs and distributor cap. Adjustment of
exhaust and intake valves for each cylinder are done at same time.
2. Rotate crankshaft counterclockwise to bring piston No. 1 to Top Dead Center (TDC) on
compression stroke. "UP" mark on camshaft pulley should be at top, and TDC grooves on
camshaft pulley should align with cylinder head surface.

TDC groove (White mark) on crankshaft pulley should align with timing pointer and distributor rotor should point to spark plug wire No. 1 on distributor cap.

3. Measure clearance between valve stem and rocker arm.

Adjust valve clearances to specification if necessary. Loosen valve adjuster lock nuts and turn adjusting screw for each valve on cylinder No. 1. Go to next step.

4. On Accord and Civic with D16Y5 or D16Y8 engine, tighten valve adjuster lock nuts to 14 ft. lbs. (19 N.m). On Civic with D16Y7 engine, tighten valve adjuster lock nuts to 13 ft. lbs. (18 N.m). On all models, check valve clearance and repeat sdjustment, if necessary.

5. Rotate crankshaft counterclockwise 180 degrees (camshaft pulley rotates 90 degrees). Ensure
"UP" mark on camshaft pulley is on exhaust side and cylinder No. 3 is at TDC. Adjust valves
on cylinder No. 3. Repeat step 4 and go to next step.

6. Rotate crankshaft counterclockwise 180 degrees (camshaft pulley rotate 90 degrees). Ensure
"UP" mark on camshaft pulley is pointing downward, TDC grooves on camshaft pulley are
aligned with cylinder head surface and cylinder No. 4 is at TDC. Adjust valves on cylinder
No. 4. Repeat step 4 and go to next step.

7. Rotate crankshaft counterclockwise 180 degrees (camshaft pulley rotate 90 degrees). Ensure
"UP" mark on camshaft pulley is on intake side and cylinder No. 2 is at TDC. Adjust valves on
cylinder No. 2. Repeat step 4 and go to next step.

8. After adjusting valve clearances, retighten crankshaft pulley bolt to 181 ft. lbs. (245 N.m) on
Accord and 134 ft. lbs. (182 N.m) on Civic. Install timing belt upper cover, valve cover, spark
plugs and distributor cap. Tighten timing belt cover and valve cover bolts and nuts to 89 INCH
lbs. (10 N.m). Tighten valve cover bolts sequentially in 2 -3 passes. See Fig. 9 or Fig. 10 .