High idle rpm + hyundai santro

SOURCE: miss fire #3 cyld. compression 125psi idle speed 2500 rpm

Hi

A faulty IAC would cause a random misfire rather than a misfire in a specific cylinder, as would an intake air leak, both of which would cause a high idle amongst other things.

Run the engine until its good and hot, disconnect the injector harness plug so the injectors are disabled, remove all the spark plugs, disable the ignition by unplugging the wiring connector(s) from the coil pack(s), and then carry out another compression test on al the cylinders.

If the compressions are now all relatively the same then you very highly likely have a faulty injector in cylinder 3.

Very best regards

Geordie

SOURCE: 1998 ram 1500 5.9 gas rough idle,hissing sound from air filter

SHOWING MISFIRES ON SCAN TOOL?IF NOT,ENGINE CONTROLLER HAS NOT LEARNED MISFIRE MONITOR..WILL HAVE TO BE DRIVEN A BIT FOR RELEARN..IF YOU CAN SEE MISFIRES..MISFIRING ON MORE THAN 1 OR ALL CYLINDERS?CHECK UNDERSIDE OF IGNITION COIL FOR CRACKS..IF NOT CRACKED,YOU MAY HAVE A FAULTY CRANK SENSOR..ANY CORRODED PLUG WIRES AT DISTRIBUTOR CAP?ALSO CHECK IF ANY OIL PRESENT IN INTAKE MANIFOLD..GASKET ON BOTTOM OF INTAKE MAY BE BROKEN CAUSING AN INTERNAL VACUUM LEAK

Harvey N Tawatao

• 3854 Answers
• Posted on Jul 04, 2009

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: 1996 Honda Accord Rough Idle Even After tune up

Perform a valve clearance inspection and adjust if necessary. Tight or sticking valves will cause a misfire or rough running concern. Note: Perform valve adjustment when the engine is stone cold. 4cyl: INT 0.26mm EXH: 0.30mm (V6 engine are hydraulic and no adjust necessary.) Also check for a sticking or stuck open EGR valve. For diagnostic purposes only: Remove the EGR valve. Place a business card over the EGR passage and bolt the EGR valve back on. This plugs the EGR ports and if the misfire goes away the EGR valve is partially stuck open and is defective.
Check for low fuel pressure. Check for low compression. Check cam timing. Check for a weak ignition coil. Also don't over look the possibility of worn or broken engine mounts which cause excessive engine movement and engine vibration. -hope this helps

Delage guy

• 167 Answers
• Posted on Apr 29, 2010

SOURCE: 1998 camry 5sfe engine, surging at idle

Check for air leaks in the vacuum pipes in and around the inlet manifold, they have a habit if going brittle and splitting.
Another possibility is the temp sender , if the ecu thinks the engine is too cold it will compensate causing the engine to " hunt". This can be something as simple as a worn radiator cap seal letting air into the cooling system and tricking the sensor.
Hope this helps, Marshall