2001 volvo penta 5.0gi pefs rough idle

Donald Fierce

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Mar 13, 2018
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I have a 2001 volvo penta 5.0gi pefs that runs rich at idle. So much so that plugs are fouled and idle is rough.
I did the following: changed plugs, distributer cap and rotor, plug wires, new idle air control (IAC) valve, manifold air pressure sensor, thermostat. Noticed that IAC never retracts. Unpluged IAC and manually screwed pintle in to a point where the idle is smooth. What can I check next? Would a bad throttle positon sensor cause the IAC to behave this way?
 

alldodge

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Mar 8, 2009
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Unpluged IAC and manually screwed pintle in to a point where the idle is smooth.

Howdy

This tells me the ECU is not controlling the IAC, your new IAC is not working or maybe wrong one installed.

Otherwise this is is caused by a bad ECU of wiring going to the IAC. Suggest the first thing that needs to be done is use an ohmmeter and check connections between the IAC and the ECU. Next have your motor scanned for codes.
 

QBhoy

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Mar 10, 2016
Messages
8,286
Does sound like ecu over fuelling.
Can’t think, but is this engine a single point injection ? If so, is it worth checking the operation and condition of the throttle body ? Perhaps not allowing enough air in ?
 
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