Och Posted October 8, 2009 Share Posted October 8, 2009 Whats up guys, this problem just started yesterday. When I start the car, idle stays low, pretty much at 650rpm - which is the normal speed for when the engine is warm. It of course makes for a rather rough/vibrating idle until the car warms up. When it warms up, the car is perfectly normal, idle doesn't drop below 650, everything is nice and smooth. So what could it be? I have a few theories. 1) ECT Sensor - it could be broken and telling the computer that the engine is warm, and therefor the computer isn't sending enough fuel. But I kind of rule that out, because that would create problems on acceleration while the engine hasn't reached operating temperature. Plus, on a cold start the exhaust has a heavy gas smell, so I'm more inclined to think that it isn't getting enough air. 2) Cold start injector - I really don't know how it works and whats its function. Can somebody shed some light onto that? 3) Idle Air Valve - thats my most likely suspicion. Could it be that its not opening and the engine isn't getting enough air? But in that case, wouldn't I still have a problem once the engine is warm? Quote Link to comment Share on other sites More sharing options...
lexfourcam Posted October 8, 2009 Share Posted October 8, 2009 i'd say you need a new cold start valve. what is the healthy cold idle? my car usually idles at 1200 or 1400 when it first starts. but if i put it into gear it'll drop down to like 1000. Quote Link to comment Share on other sites More sharing options...
CBLex Posted October 8, 2009 Share Posted October 8, 2009 Please repost whatever your solution may be as I too am having the exact same problem. Thanks a bunch! Quote Link to comment Share on other sites More sharing options...
curiousB Posted October 8, 2009 Share Posted October 8, 2009 Could be engine coolant temp (ETC) sensor is fooling the ECU to think car is warm when it isn't. I would have thought a code would be logged for this though so maybe check ECU log with reader. Temperature sensors generally fail to an open circuit so the higher resistance would mean colder reading to the ECU. That doesn't seem to jive with what you are seeing. Might be dirty or clogged IACV. If the ECU is calling for higher idle it has to open up the IACV more to let more air around the throttle plate. If the valve is sticky or somehow clogged it may not let enough air by to speed up engine. Could be MAF sensor. Maybe just dirty and it isn't reading well at lower air volume levels (i.e. idling). Quote Link to comment Share on other sites More sharing options...
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