start up cold idles rough,smell of gas-no leaks, large vac sound from throttle body for about 20 sec.-start to drive , engine lacks power and boggs like a carb. thens runs fine when warmed up well. also no codes stored.
Welcome to the forum. This is usually an indication of a temperature sensor problem, the computer thinks the engine is warm and starts running on closed loop as soon as it starts, but it should be on open loop cold running. It changes when it warms up, because the temp is then closed loop warmed up.
The large 'air rushing' sound may be the IAC (idle air control) motor opened up to allow more air to the engine. That and the smell of raw gas makes me think that the engine is running too rich when cold.
Has the throttle body blades and bores been cleaned lately? Holding the throttle blades open and scrubbing with a toothbrush or rag soaked in solvent will clean off the carbon build up. This carbon will restrict air flow past the throttle blades and the IAC has to compensate by adding more air. 80a61223.gif
During this 'cold rough idle' time, shut the engine down and pull a spark plug to look at the plug tip. If it is black and carbon fouled or even wet with fuel, it is too rich. 1028732_orig.jpg
Spark plugs will misfire until combustion heat burns off the carbon and then the engine will recover and run well.
Raw fuel will contaminate the engine oil and the dipstick will smell of gas. If this is left too long, the oil thins and must be changed.
Correct heat range and use of OEM parts are important. Are these the correct spark plugs called for on the under hood label (Champion RC12LC4)? Use of a different spark plug may cause problems when cold.
Intake manifold plenums were known for vacuum leaks in the valley pan area. This will draw crankcase air into the intake and the injectors will have to dump in more fuel to compensate for the added air.
A quick test of this is to remove the breather hose and PCV valve. Block off both valve cover holes with a finger on a running engine momentarily and then release one hole and note if there is a release of internal engine vacuum or pressure. Pressure is normal as that is the build up of blowby gases inside the engine. Vacuum is not, that indicates that the intake is leaking and drawing the crankcase into a vacuum. The intake would have to come off and the gaskets replaced. It is usually the paper bottom intake pan gasket that breaks up and leaks. 2009-12-22_030843_100_2689.JPG
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