SOURCE: engine stalls after cold start-up & release from high speed idle
I had a similar problem. I found the filter cartridge below the pcv valve had carboned up, and after the crank case pressurized, oil was forced out the pcv supply line to the throttle body. The idle air control valve solenoid got oil in it and caused my problem, but only when it was cold. The pcv cartridge is accessed by removing the pcv valve and the rubber fitting that the pcv valve mounts in. It can then be fished out with a pick set, and it is a pain because you can't see it, but you can get you hand back there. I hope this helps you.
SOURCE: throttle/Idle/running problem - wants to run too fast, or stall out
RPM's up and down check EGR valve and sensor. EGR valve and sensor control idle. That's why your getting the surging on rpm's and this could be giving out the other codes. If mass flow was bad car will not start and the same for the map sensor. O2 sensor measures gas and air for right mixer. TPS controls 0-60 speed as in throttle respons.
SOURCE: 2001 Forester, Rough idle and engine loping driving at low rpm
I had a similar problem on my 2002 Impreza RS 2.5 (same engine and engine control system). In my case it was the O2 sensor on the intake manifold. This happened at 34,xxx mi. so it was covered by the warranty. Replacing the part is very easy. (two bolts and a wiring harness). Obviously I would start simple and cheap and work your way to expensive and difficult.
From my understanding its all caused from the engine missfiring. If its been a while or never, I'd change the spark plugs first. (stick with the Subaru Parts plugs, I went after market and the dealer claimed the plugs were not the correct "temperature" and had to pay for the new plugs and install although they did it without my permition. Thats a whole nother story).
Could also be the manifold pressure sensor.
Either 02 or manifold pressure sensor may cause intermitent check engine light.
Where I live Brookline,MA , Autozone will run a free diagnostic on your car by hooking up to your ECU and will give you the trouble codes and possible remidies. Of course there are no guarentee's but it will point you in the right direction.
Good Luck
SOURCE: How to I set idle speed?
Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay. CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Drive ability problems may exist until computer systems have completed a relearn cycle.
IDLE SPEED & MIXTURE
NOTE: Idle mixture is controlled by Powertrain Control Module (PCM). Adjustment is not possible. After replacement of Idle Air Control (IAC) valve, system must be cycled as identified for PCM to properly control idle speed. If idle speed is not okay after cycling system, problem is usually caused by a dirty throttle plate or vacuum leaks. Ensure all vacuum components are functioning properly.
IDLE SPEED (4-CYLINDER)
Turn ignition on with engine off for 10 seconds. Turn ignition off for 10 seconds. Start engine and idle for 30 seconds. Slowly vary engine speed between idle and 3500 RPM 5 times. Return engine to idle. PCM will now properly control idle speed. 2.2L (Cavalier & Sunfire) & 2.4L (Alero, Cavalier, Grand Am & Sunfire) Good luck and hope this helps. If it still has the high idle problem, your going to have to buy a can if not two cans ot THROTTLE BODY CLEANER NOT CARBURATOR CLEANER. Just follow the instruction on the can and try to get the Idle Air Control Valve cleaned also which is on the sdie of the throttle body so go to town when cleaning the throttle body and then do the Idle speed relearn again. The other thing to is since your doing house cleaning, buy a MAF sensor cleaner and spray down your MAF sensor and IAT sensor also, this will help with your fuell consumption.
Good luck and keep me posted, be glad to help.
SOURCE: Rough idle engine ticking
check for a lose spark plug lead or cracked elecrod insulation on spark plug
Description
The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.
Conditions for Running the Throttle Learn Procedure
• DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.
• The engine speed is between 450-4,000 RPM.
• The manifold absolute pressure (MAP) is greater than 5 kPa.
• The mass air flow (MAF) is greater than 2 g/s.
• The ignition 1 voltage is greater than 10 volts.
Throttle Learn
Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code
(DTC) List - Vehicle.
1. Start and idle the engine in PARK for 3 minutes.
2. With a scan tool, monitor desired and actual RPM.
3. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
4. Ignition OFF for 60 seconds.
5. Start and idle the engine in PARK for 3 minutes.
6. After the 3 minute run time the engine should be idling normal.
Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
* If the engine idle speed has not been learned the vehicle will need to be driven at
speeds above 70 km/h (44 mph) with several decelerations and extended idles.
7. After the drive cycle, the engine should be idling normally.
* If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds
and repeat step 6.
8. Once the engine speed has returned to normal, clear DTCs.
Good Luck
Engine stall or RPM fluctuates
at idle.
This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control
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