rough idle

[chevytrucks79]

2003 chevy trailblazer with rough idle. already replaced the spark plugs, map sensor, camshaft position sensor, fixed a couple vacuum hoses that broke. Anything else I should check? It will idle roughly for about 5 minutes and shut off. Anybody have any ideas?

[chevytrucks79]

I'm going to elaborate a little more. For the past 5-6 oil changes, right after the oil change we'll get a check engine light. We had it checked at autozone a couple times and both said something about a camshaft problem. The truck had been running fine so we didn't worry about it because the light would go off on its own. Well the last oil change the light never went off, so I replaced the camshaft sensor on the front of the engine last week to see if that would help. It didn't. Also over the last few months the truck began to idle rough and rev up and down on a regular basis. Today I changed the spark plugs and did an oil change, but afterwards the idle was worse and the engine will shut off within 2-3 minutes. I found some cracked vacuum lines that I replaced and cleaned up the map sensor. The idle smoothed out for a little but when the gas pedal was pushed the engine did not respond. So I went and replaced the map sensor and checked the spark plugs boots to make sure I got them all on the spark plug. Well the engine responds to the gas pedal, but it is still idling rough. I don't see anything that I could of moved or changed to make anything worse. No engine light is showing up now and I don't know what else I can do.

[dadsworktruck]

i dont know what engine you got, but i got a 02 5.3 in a hoe that ran rough, but only in the winter, i retorqued my intake bolts and helped mine 99%.come spring i will replace the gaskets..be careful tightening the bolts, plastic stuff breaks....

[chevytrucks79]

Well here is another update. When I went back to the store to see if they could read any code the truck ran great. No problem whatsoever. So I came home and just let it idle a bit to be sure everything cleared up. My ever-oberservant wife soon discovered that the idle would screw up when she turned on the heat or ac. When it was off then it would idle great. So now I have to figure out what is making it screw up. I know carburated engines with ac would have a solenoid that would bump up the idle a bit to give the engine more power to compensate for the compressor being on. On this computerized thing I have no idea what that equivlent part would be other than some solid-state device. It has a 4.2L straight six.