wandering revs
17 November 2006, 05:44 PM
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wandering revs
Hi everyone, just bought an sti3 which has only done 44000 miles a fresh import from japan. On idle the revs hunt around from between 700 to 13000rpm, took it to the scoobyclinic yesterday and they changed the MAF they also fitted a full decat for me. Unfortunately its started doing the same thing again on the way home. Taking it back next week but just wondered if anyone else has had a similar problem. Cheers Cliff.
18 November 2006, 12:32 PM
#7
The correct idle should be around 850-900 rpm.If it drops below 850, the ECU tries to lift it back up but in your case is overshooting which is quite normal.
One of the frequent causes of poor idle is incorrect mixture/AFR.
I assume you have O/E ECU.
O/E air filter box? Check there is an air filter in the box.
Look for a vacum/boost pipe disconnected from the inlet manifold and check each pipe along its entire length to the point it connects with fuel pressure regulator, dump valve etc.
Also check the pipes into the inlet tract are in position and the inlet tract is properly connected, especially after the MAF sensor.
If all that looks OK, get a medium size Phillips screw driver and slacken the two screws on either side of the Idle Control Valve System. This is in front of the top mount intercooler, to the right of the throttlebody, has a wiring plug to it and a bakalite or similar top with something like ABC on it.
By tapping this you can move the valve in the slotted adjuster to increase/decrease tickover. Slightly increase tickover and see if you can smooth it out but not going beyond 950 rpm. Lower if possible.
If that does not cure the problem then we have to start looking elsewhere.
One of the frequent causes of poor idle is incorrect mixture/AFR.
I assume you have O/E ECU.
O/E air filter box? Check there is an air filter in the box.
Look for a vacum/boost pipe disconnected from the inlet manifold and check each pipe along its entire length to the point it connects with fuel pressure regulator, dump valve etc.
Also check the pipes into the inlet tract are in position and the inlet tract is properly connected, especially after the MAF sensor.
If all that looks OK, get a medium size Phillips screw driver and slacken the two screws on either side of the Idle Control Valve System. This is in front of the top mount intercooler, to the right of the throttlebody, has a wiring plug to it and a bakalite or similar top with something like ABC on it.
By tapping this you can move the valve in the slotted adjuster to increase/decrease tickover. Slightly increase tickover and see if you can smooth it out but not going beyond 950 rpm. Lower if possible.
If that does not cure the problem then we have to start looking elsewhere.
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