951 won't hold idle when starting cold
05-18-2005, 12:48 PM
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951 won't hold idle when starting cold
'86 951 engine will not stay running at idle speed when first started cold, so the engine has to be revved to keep it from dieing. After it's warmed, the engine will idle smoothly.
Temp sensor?
Vacuum leak or hose?
Idle control valve?
Suggestions?
Temp sensor?
Vacuum leak or hose?
Idle control valve?
Suggestions?
05-18-2005, 06:13 PM
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Generally the ISV sticks in it's closed condition, the solenoid can't pull it open, and something goes "pop". Time to replace the ISV.
The whole point of the ISV, is that on cold, the DME signals it to open (itself on a signal from the temp sensor). When warm, the ISV is not needed, the DME signal is changed, and the valve closes (hence when warm, you get no problems).
Hence, it could be the sensor, the ISV, or in extreme cases, even the DME gone bye-byes.
Oppositely (if that's a word!), if you have a leak in the pipe, the IC pipe and the throttle body will pull in air, and actually run high (as if the ISV is open) in a warm engine. Exactly the opposite symptoms.
The whole point of the ISV, is that on cold, the DME signals it to open (itself on a signal from the temp sensor). When warm, the ISV is not needed, the DME signal is changed, and the valve closes (hence when warm, you get no problems).
Hence, it could be the sensor, the ISV, or in extreme cases, even the DME gone bye-byes.
Oppositely (if that's a word!), if you have a leak in the pipe, the IC pipe and the throttle body will pull in air, and actually run high (as if the ISV is open) in a warm engine. Exactly the opposite symptoms.
