PaleFire

After picking up the car on Friday and spending the afternoon driving around I was unable to get the car started again once I turned it off. When I turned the key I would hear a single click and nothing else. The previous owner rarely drove it and the battery was only pushing about 9V. Aside from a wandering/surging idle (~1300 to 1600rpm) the car drove fantastically so I assumed a new battery would fix my problems. Hooked everything up, turned the key, *click* ...

I had plans for the weekend so not being able to drive the new toy nor having the time to tinker with it was a huge disappointment. However, thanks to these forums I was able to track down and fix my starting problems this evening for a total cost of $0.29. That stupid clutch switch.. More specifically, that stupid plastic stopper piece must have disintegrated on the drive home Friday. I noticed the remains on the floor mat but didn't think anything of it. Oh well.. Fired right up with the nut in place. Which brings me to the idle issues..

The engine was idling high at 2500, 2000, or 1500rpm. Usually right at 1500 or 2000. Aside from the high idle it was a pleasant night time drive with nothing obviously wrong. However.. as soon as I turned the headlights off the wandering/surging idle from the first day returned. The rpm would bounce back and forth from ~1300-1600 or so. Pop the headlights back up and it stabilizes at 1500. I was thinking maybe vacuum leak but the surging occurring when the battery isn't under load is throwing me off.. Alternator? Ground? Any help would be appreciated.

Sgtblue

iTrader: (16)

Idle air control maybe? It's on the firewall side of the throttlebody and easy to access. IIRC it's suppose to control idle under load variation like you described. Make sure it's plugged in. But they can get carbon-like deposits over time that a little brake parts cleaner will cure. Just two 10mm nuts and the connector.

TomU

iTrader: (11)

and what ECU is installed?

Mike93r1

iTrader: (5)

You may also check the grounds in the engine bay. I had similar issue with my FD and cleaned up the grounds at the UIM to fire wall and battery grounds to the engine block. That helped my car quite a bit and maintained a good smooth idle. This was with the stock ecu.

Sgtblue

iTrader: (16)

^Couldn't hurt. With the stock ECU there was some collective knowledge back in the day that it helped some with the usual "3k hesitation" as well. Most, including me, also added supplemental grounds. Some 6 ga. or so wire, battery to engine, engine to chassis, chassis to battery.

PaleFire

ECU is the original as far as I know. The previous owner had the car for 12 or 13 years and kept any modifications to a minimum.

Checking the idle air control valve and cleaning up (perhaps adding a few) the grounds sound like a good place to start. Thanks for all the recommendations

Sgtblue

iTrader: (16)

And make sure the throttle and cable are free and everything is returning where it should.

dark_takumi

Was the issue solved? My fd does the bucking at 3k and I really can't justify replacing a whole new ECU if it's not 100%

Sgtblue

iTrader: (16)

Not likely to be an ECU issue. Explain "bucking at 3k". ???

PaleFire

Well it starts just fine, the idle is still high for the first hour or so of driving then it's fine. I think it's either the idle air control or something.