Before I bring my wife's 1998 es300 for an idling start up problem, I'd thought I'd try and get some advice. Basically, her car will start, but dies as soon as you take your foot off the gas pedal. It seems driveable, but you have to keep the rpm's up by throttling it, which can't be good. Is this something like a relay or fuse that I can replace myself? My
*very* basic instincs tell me this is probably electrical related but my remedial highschool auto power experience keeps me from accuratley diagnosing it. I am, therefore, at the mercy of a Mechanic.
Any thoughts, advice or experience is greatly appreciated.
There are several things that can make your wife's 1998 ES 300 idle RPM too low without a check engine light.
If it idles poorly on cold startup and the idle improves later as the engine warms up, check the coolant temperature sender. I think there are 2 senders on your wife's car, one for the electronic control module (ECM) and one for the gauge. In either case, the voltage put out the sender should go up as coolant temperature goes up.
If it idles poorly on cold startup and continues to idle poorly after the engine is warm, there are more things to check:
Check the air filter to make sure it is not clogged. You should be able to see a light shining through the filter element from the back side.
Check for cracks in the plastic intake snorkel between the air filter and the throttle body, including the under and back sides of the snorkel.
Check the idle air control (IAC) module on the throttle body. It should allow some air to enter the intake when the throttle plate is closed. The IAC is not really serviceable, but you may be able to resurrect it by cleaning it with a cotton swab and isopropyl alcohol or Pine-Sol or Simple Green. Do not use carb or throttle body cleaner on Toyota/Lexus/Scion IAC's.
Check the mass air flow (MAF) sensor, which is next to the air filter box. There is a thin wire in the sensor that heats up and is cooled as air flows past the wire, and if the wire gets coated with dirt or residue, then it can give bad readings to the ECM. Again, the MAF is not really serviceable, but you may be able to resurrect it by cleaning the wire with a cotton swab and isopropyl alcohol or Pine-Sol or Simple Green. Do not use carb or throttle body cleaner on Toyota/Lexus/Scion MAF sensors.
Lastly, the interior of the throttle body may be gummed up, but poor idling is usually not a symptom.
One thing I think is also worth mentioning; the car will not start unless I'm giving it gas. Once it starts, I have to keep it reved or it dies. If I try the ignition w/o giving it gas, it turns over but will not start.
That moves the idle air control valve a little higher on the list of suspects, moves the MAF down the list, and adds throttle position sensor. I'd start by checking the IAC first.
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