89lxiaccord

i have an 89 accord 2.0 auto f.i. that has been giving me trouble. idle jumps between 1000 and 2000 rpm when in park or neutral but goes away if put in drive or reverse. last night while driving home the check engine light came on and it got a lot worse. it seemed like it was missing even when in gear, and in park or neutral it raced between 1 and 2k rpm's. dont know much about these cars and would appreciate any help. after shutting off the car and restarting the check engine light went out and it runs better but still revs up and down. any ideas?

e3NiNe

Could be a jammed PCV valve. Give that a shot first, the part is under $5.

If not, this sounds like the infamous "fast idle thermo valve" issue seen in the later generation Accords.

89lxiaccord

i have checked the pcv and seems ok. at times car does run good, idles smooth at about 900 rpm in park. unplugging any vacuum line from the manifold causes the same idle problems, surging idle and goes away when plugged back in. i have checked several times for a vacuum leak and found none.

89lxiaccord

what is a fast idle thermo valve and where is it located? also is there any way to pull codes on an 89. read in a chilton manual that the ecm stores codes. any way to get them if the check engine light is not on?

98CoupeV6

When the CHECK ENGINE warning light has been reported on, turn the ignition on, move the driver's seat to the front position and observe the LED on the rear of the Electronic Control Unit (ECU). The LED indicates a system failure by it's blinking frequency.

If the ECU indicates codes 4, 11, 15, 16, or exceeds 17, count the blinks again. If the indicator is blinking these codes, substitute a known-good ECU and recheck. If the indication goes away, replace the original ECU.

The CHECK ENGINE warning light and ECU LED may come on, indicating a system failure, when in fact, there is a poor or intermittent connection. First, check the electrical connections, clean or repair connections if necessary.

Fast Idle Testing:

Testing and Inspection


NOTE: Do not attempt to disassemble the Fast Idle Valve, it is factory adjusted.



Start the engine.
Remove the cover of the fast idle valve.



Put your finger on the valve seat area and make sure that there is air flow with the engine cold (coolant temperature below 86°F, 30°C) and idling.
If there is no air flow, replace the Fast Idle Valve and retest.
Warm up the engine to normal operating temperature (the cooling fan comes on).
Check that the valve is completely closed (no air suction can be felt in the valve seat area).
If any suction is felt, the valve is leaking. Replace the Fast Idle Valve and recheck.





The Fast Idle Valve, mounted on the throttle body next to the throttle angle (TPS) sensor, raises the idle speed when the engine is cold. The Fast Idle Valve is controlled by a thermowax plunger type valve. When the engine coolant is cold, the thermowax contracts the plunger allowing air to bypass the throttle plate and idle adjusting screw into the intake manifold. When the engine coolant warms up, the valve closes and the bypass air flow is blocked.

89lxiaccord

thanks for the detailed info 98coupev6, thats what ive been looking for. i will check all those areas and let u know what i find.

89lxiaccord

checked the fast idle valve and seems to be ok. also replaced pcv valve and hose but still have rolling idle in park. check engine light has not come back on yet. is there any way to get codes with light off? does the ecu store codes? i was told maybe i have an idle air control valve problem. is it possible? is there any way to check it and where is it located? sorry so many ?'s, i just bought this car just to get me back and forth to work and sometimes i dont think it will make it.

89lxiaccord

still trying to figure this damn car out. any ideas what to look for?