very high cold idle

[caprisecca]

just like the title says, what is causing my high idle when engine is cold? im talking like 2800 rpms. once the car warms up it idles around 1200 rpms. that might be a hair high too. any way i have checked for vacuum leaks and have not found any, the car also has new plugs, wires, cap, and rotor, and thermostat. i have had the car about 6 months now and havent been to worried about this but now that it is getting cold it is hard to start. its a 90 efi 5 speed. any ideas and i would sure appreciate it.

[dalebwilson]

I would check the dash pot plunger near the idle stop screw. It sounds as if it may be sticking open when cold. Once you have verified that it is ok, base idle must be set correctly. If this is a B3, here is a quick procedure:

-With the engine warm and off, ground the STI self test connector near the brake booster. (single black connector with yellow/green wire)
-Start engine and adjust idle speed by turning the idle air adjustment screw on top of the throttle body. (has small black rubber cap covering screw)
-Idle should be set @ 750 RPM under normal conditions (Remember that ignition timing can affect idle and visa versa. Timing should be set @ -10BTDC)

Another thing to check is your idle air control valve mounted behind your intake. They have a tendency to get gummed up and not function properly.

[Ninjawimp]

I also have been seeing these problems in my festiva lately. I'm corious to see what it is. I have checked my dash pot. A bit rusty on the bottom side cylinder but still slides. Could you sand down & re-oil or just replace with new? I was thinking something like a stuck iac?

[drddan]

How would one properly clean the IAC?

I had a high idle problem, like you describe and I backed off the dashpot so it couldn't high idle the engine. Then adjusted the idle screw on the intake

[dalebwilson]

How would one properly clean the IAC?

I had a high idle problem, like you describe and I backed off the dashpot so it couldn't high idle the engine. Then adjusted the idle screw on the intake

The IAC can be removed, placed on a bench and then all ports filled with Marvel Mystery Oil. Let it soak for 24 hours and then blow out with compressed air. The IAC has a wax valve inside that opens/closes in relation to the hot/cold antifreeze circulating through it.

It is important to know that when you adjust the factory set idle stop screw near the dashpot, that you may affect the TPS adjustment as well.

[harpon]

Check the cable itself too- may need some lubrication and getting stiffer in the cold-

I literally pull the accelerator backwards with my foot to get to slow idle- and probably next spring I'll look into it-

the 'new' 91 is garaged for the winter

[caprisecca]

Thx for the responses fellas I'll check and see how it goes

[WmWatt]

I spray all carb linkages once a year when I spray the carb with carb cleaner during annual tuneup.
Don't know equivalent procedure for EFI engines. Sorry about that.

[nitrofarm]

I would check the dash pot plunger near the idle stop screw. It sounds as if it may be sticking open when cold. Once you have verified that it is ok, base idle must be set correctly. If this is a B3, here is a quick procedure:

-With the engine warm and off, ground the STI self test connector near the brake booster. (single black connector with yellow/green wire)
-Start engine and adjust idle speed by turning the idle air adjustment screw on top of the throttle body. (has small black rubber cap covering screw)
-Idle should be set @ 750 RPM under normal conditions (Remember that ignition timing can affect idle and visa versa. Timing should be set @ -10BTDC)

Another thing to check is your idle air control valve mounted behind your intake. They have a tendency to get gummed up and not function properly.

Yes do this but make sure you shut the car OFF then remove the Jumper. ie don't take the jumper off while its still running. If you do all this and you still have issues. And you know your IAC is good,you might look at installing a new computer. I had high idling issue that was caused by Me damaging my computer. I had left my lights on all weekend,and used the "START" selection om my Charger Monday am. Once I got the car running I didn't turn the Charger off before disconnecting the clamps(late for work & rushing). When I disconnected I saw a large arc,then on the way to work I realized I was way down on power. I fried my Dizzy,Alternator and ECM. The last thing I had to replace was my ECM due to the high idle and slow timing advancing I was getting. This was on an Aspire but the Festy's computer basically works the same way.Took me a couple weeks to get it all sorted out.