2001 Toyota Corolla, automatic with 198,084 miles, cranks for a long time before starting in warm, humid weather or if it has sat 20+/- minutes on a warm humid day. Starts right up when 32 deg or below and dry. Technicians could not figure it out. They replaced Mass Air Flow Sensor, checked fuel pressure, all sensor readings and cleaned throttle...all to no avail. They even called around to friends, and nothing....can you help?
generally there is some type of computer problem in the warm-up system when it's really cold it sprays extra gas in it obviously that is working when it's really cold but it seems like it doesn't work when it isn't those cold. Have a good mechanic check the cold start system especially the temperature sensor for the computer
Did ya check fuel pressure regulator too? Possible but usually has long start no matter the temp depending on how long it's been off. Can I also assume that in warm humid weather after it is started and shut off for a few minutes (engine not cold or hot, just warm) it has same issue? Or does it start right back up?
Also, put fuel gage on rail, shut engine off, how long does pressure stay?
I am not familiar at all with the intake on this particular car. However cars of this generation sometimes have an ISC motor with a bypass air circuit whose default or base setting is adjusted by a screw. When it is warm, the computer will position the ISC motor to reduce the bypass air during starting. When the car has as many miles as yours does, loss of compression can mean the engine won't light off right away on the reduced idle air. You could back the screw out one turn (mark the position before) and see if that improves the problem; that would just take a minute to do. That will increase the minimum idle air available, but once the engine starts the computer will modulate the ISC motor and RPM will be controlled to specification. I had a car that responded to this "fix." If it doesn't help, you can reset the screw and try some of the other fixes suggested.
