Car shakes when engine is running, and more when air conditioning is running.

many people experience a shaking or vibration when the Air Conditioning is on when they have an issue with the AC Compressor. It's also possible there could be a clogged up vent/duct. Bear in mind, air conditioning systems usually weigh over 100lbs in a car and do put a considerable amount of extra strain on the engine to run them, so most every car will be 'bogged down' a bit, but it shouldn't be too significant. So if the problem is mostly noticeable when you are stopped at a red light, or idling in some way - I wouldn't be too concerned.

Please refer: http://www.engine-light-help.com/P0304-check-engine-light.html

Check condition of the following:

1) Spark plugs, leads and coils
2) Air filter
3) Fuel filter.

look at your idler pulley since the ac clutch runs on the serpintine belt its moving alot faster the berings are prob bad in it takes 10 minutes to take off and 17 dollars to replace n another ten but if you take it off spin it in your hand if its rubbing n stopping fast(should spen fast like a skateboard wheel) then its bad that could be all it good luck hope this helps

remove the spark plugs and look at them for cracks and black carbon tracking

You need to check the choke on the engine for cold starts it chokes off air to the fuel mix . if it is closed to much the engine will want to die and shake. When the car warms up the choke opens and the car gets air and runs fine although the choke could just be part open. It still will need adjusting.

Hope this helps

Mike

there are a few possibilities that could cause this one is a dirty mass airflow sensor or an oxygen sensor giving false information to the pcm. i have a few things to try if you have an ls option package or higher you have a 3800 series 2 engine the mass air flow sensor is on the top of the throttle body. to clean this sensor, remove sensor by taking two screws off top unhook wire connector and lift up. this is sensor upside down clean the little wire in center with carb cleaner just spry through the hole shake it a few times and reinstall. start engine see how it runs. if you have a 3400 remove silver sensor from air inlet duct running from throttle body to air filter box (check for signs of mice in air box due to sitting for a period of time prior to problem) loosen two clamps on sensor,unhook wire connector and wiggle out sensor spray wires clean with carb clean shake a couple of times and reinstall (do not touch wires with fingers) start car and test. the other possibility is 02 sensor the easiest way to figure this out is to unhook the precatalyst sensor if you look over the back of the engine( on either engine) were the exhaust comes off of engine there is a sensor there un hook it start car and run it see if condition improves.

Misfire means you need spark plugs replaced. Or spark plug coils.

That's why the whole car starts shaking because its running basically on 3 cylinders and not 4 as supposed. There is no gas compression on the 3rd cylinder because once again the spark plug is "misfiring"

There also might be even a bigger problem which could be the distributor cap where the coils are connecting outside the engine.
once you fix the problem the check engine will turn off immediately

hope that helps.

there are several possibilities. by bogging down do you mean the engine runs smooth but looses power? or does the engine/car start shaking and doesnt want to go any faster? if the engine runs smooth and doesnt seem to be shaking...can you hear a noise from the engine compartment? or a hi pressure noise from the rear of the vehicle - like a vacuum cleaner? if so then you probably have a plugged catalytic converter. if the engine seems to shake the van and looses power until you let up on the throttle slightly then you have a misfiring condition which can be caused by bad plug wires,plugs or a coil breaking down. as you shift up in gears the spark needed to each cylinder is increased and if you have bad plugs,wires or coil the spark wont get to the cylinder when it is needed. see if any of this sounds similar to your condition and request more info from me if ya like. good luck. carefull the converter can cause a fire if it gets too hot!

Check condition/operation of the PCV valve.
Ensure associated crankcase vent and vacuum hoses are in good order and not leaking.
Check for air leaks on the engine air induction system, including air cleaner etc.

When you put your A/C on, there is Vacum Motor or Solonoide, that increases RPM of the Engine to compensate the load of an A/C. If the vacum hose is leaking or raptured the RPM of Engine remain low and Engine Shakes. When you put the A/C on and the RPM of Engine Increases, but a little, then your Selonoide is working but not adjusted properly, so adjust it for the proper RPM of the Engine. Put all the loads on, I mean Head Lights and A/C on and then ajust the RPM.