Check engine light on but car runs good then when i tightend up the piece on the right side i over turned it and cracked it witch means i need a new valve cover but if i replace it will it make the engine light go off a dodge neon 2000 ps the engine light was on before i cracked the piece on the right side maybe because the piece was not conected tight enough i don't understand because it was not on 4 a wile about 2 days after i did not tightend it all the way so then when the light came on i over turned it and cracked it now i'm about to take it to auto zone check engine and buy a valve cover but i realy wanna do it by myself can i

You wouldn't think a gas cap would be that important, but it is. When it's loose or cracked, fuel vapors leak out and can throw the whole fuel system off. This causes a reduction in gas mileage and increases emissions.
What causes it: If you get an error pointing to the gas cap it means fuel vapors are leaking out of your cap. This means the cap is either cracked or just wasn't tightened well enough.
What you should do: If your car isn't feeling jerky or strange when the check engine light comes on the first you should check is the gas cap. Pull over, retighten it, and take a look at the cap to see if it has any cracks in it. Continue driving and see if the check engine light turns off. Alternately, you can purchase a gas cap for about $3 at an auto parts store. All you need to do is take the old one off and screw on the new one. If you've already made it to the store, you might as well just replace it. While not car-threatening, it's good to take care of this right away to improve gas mileage.

If the lights work OKit means the ground to the battery must be good as well as the posivtive connection .But the bat also grounds to the engine block in several places along with special wire called a fuseable link . Witch is basicaly a restance wire its like a fuse if it gets to hot it burns out you can tell by twisting it between your thumb and index fingers the jaccket will move om the wire it comes off the hot side of the bat.Next check the relay this is located on a 4.3 engine center fire wall rear of engine it may have 2 3 of 4 relays depending on witch model you have 3 is most common and its #2 but there interchangeable so you can plug a differant one in if you think the relay is bad and see if it cranks. Next do you hear a click when you turn the key if so this means you are getting power to the solinod witch is the part that makes the starter engage if you do then everything is working with the relay and fuseable link although it still may be a bad or connection to the starting motor always check your gounds first . You can try pulling on the cable its red and runs down to the starter its on the passangers side of the vehicle and comes from the battery see if it will crank . If not you have eighter a bad starter solinoid or you have a problem with your key switch witch is unlikely if your lighting works . I have to be honest the starter will come out but its not easy to get it out it will fix but has to be at the exact angle to remove and costes a cuople of hunderd dollars and then you may have issues with shimeing behind the bolts to correctly allinging the bendex drive to the flywheel . Theres just not a lot of room to get at it Good luck with it

It could be MAF mass air flow sensor, IAC idler air control valve, fuel filter or a vacume leak.

Sounds like the oil pump has given out or the pick up screen could be clogged up. You will lock up the engine if you try to run it this way. Have the oil pump checked as well as the pick up screen.

The next time it doesn't start you need to check the fuel pressure. Also check to see if you can hear the fuel pump buzzing. Just remove you gas cap and and put your ear up to it and had have a helper turn the key on. You should hear it buzzing. If you don't hear any noise I would suspect a bad fuel pump or fuel pump relay. If your pump is working and the pressure is correct you will need to see if the injectors are receiving a pulse. To do this you will need a noid light which is easy to use. You just unplug an injector and plug in the light. Then then try starting and if the light flashes that means it is being pulsed. If no pulse remove your distributor cap and rotor and look for cracks in the piece underneath where the rotor sits. Sorry the name for the piece escapes my mind right now. Anyway they are common for cracking and will cause your symtoms. If that is the case you will need to replace the distributor shaft piece. You can by remanned distrubutors if you want or just rebuild yours. Hope this helps

WHEN YOU TURN THE IGNITION SWITCH TO ON POSITION.CHECK ENGINE SUPPOSE TO BE ON AND WHEN CAR STARTS THE CHECK ENGINE LIGHT SHOULD TURN OFF.CHECK PCM FUSE MAKE ITS IN PLACE TIGHT.IF ALL LOOKS GOOD.PCM HAS GROUND PROBLEM OR SHORTING OUT BY FAILING LET DEALERSHIP CHECK IT OUT.

could be just head gasket and bad exhaust manifold gasket (coolant leaks past head gasket into exhaust port then leaks out of exhaust manifold gasket)
or it possible that head is cracked too
Only way to know for sure is to remove head and inspect it

Check the fuel lines under the car. Don't actually start the car though, just turn the key until you hear the fuel pump turn on. This will load the fuel system and you will be able to see leaks (or sprays) under the car because of the pressure. If there are no leaks, see if the car runs perfect with a full tank of gas compared to a low tank. It should drive good turning left, but it might **** turning right or after a sudden stop. This could mean you have a crack in the seams of your gas tank or that your fuel pump is going bad (or a little of both).

Does not mean you need a new engine, it mean's the the ECM, the car's engine management system has detected a issue that caused your engine to stop running. Have the car scanned for the DTC code which would indicate the issue that needs to be addressed to have the engine run 100% again. It could be as simple as a dirty fuel filter that needs to be replaced. Good luck and keep me posted, be glad to answer any questions you may have. 

i would highly recommend getting it checked out by either a shop or someone you personally know and trust that has auto knowledge... the black oil leak is most likely engine oil... the light and thin aluminum manufacturers use now days can break under just the right conditions... heat and stress... when the tire piece went under your car it may have hit your oil pans(engine and transmission.. red oil) and caused either the pan gaskets to leak.. or maybe even the pans them selves to get cracks... hopefully it's just the gaskets... not too hard to fix and ALOT less costly then new pans... as for the light .. no clue what it's supposed to be...but good luck