I have a 2002 saturn vue v6 3.0, cranks but wont start

A random/multiple misfire in a 2008 Saturn Vue can be caused by a variety of issues. Some common causes of misfires include:

1. Spark plugs or ignition coils: Worn or fouled spark plugs or faulty ignition coils can cause a misfire. These components should be checked and replaced if necessary.
2. Fuel system: A clogged fuel injector or a problem with the fuel pump can cause a misfire. The fuel pressure should be checked and any clogged injectors should be cleaned or replaced.
3. Vacuum leaks: Leaks in the vacuum system can cause a misfire. These leaks should be located and repaired.
4. Exhaust system: A clogged catalytic converter or a problem with the exhaust manifold can cause a misfire. These components should be inspected and any necessary repairs should be made.
5. Engine control module (ECM): A problem with the ECM can cause a misfire. The ECM should be checked and reprogrammed if necessary.

It's recommended to have the vehicle scanned with a diagnostic scanner to retrieve the trouble codes and determine the source of the problem. Once the codes are retrieved, it would give a better idea of what component is causing the misfire.
It's always recommended that you take your vehicle to a professional mechanic to diagnose and fix the problem, as these are complex systems and require specialized knowledge and equipment to fix.

Questions;

Mileage?
Fuel trims?
Mysteriously losing coolant?

Suggest you do a compression test of all 6 cylinders for a comparison. Keep track of the spark plugs for clues... sooty vs clean, odd bank vs even bank.

you may be hydro locked. pull your air filter and see if it's full of water. then pull your spark plugs and turn the engine over. see if you blow any water out of the cylinders. if you didn't damage it, you should be able to get it started with a new filter and spark plugs.

having PO 304 = Misfire cylinder 4,PO 306 = Misfire cylinder 6, as I read above you have done the most. The thing that you have missed is to check whether the Catalytic Converter is faulty or not. To get an idea check whether you have a smell like rotten eggs at the end of the exhaust,you start having problems with cat and needs replacement. My advice before you go for a cat replacement is good to visit an MOT center and check your emissions and then you decide,

The P0304 indicates the #4 cylinder is misfiring. The flashing light means the cylinder is not firing at all...It could be several things causeing it, coil, wires, plug, injector or vacuum leak. Do not drive your vehicle until you have this repaired, as it will lead to further more costly problems. Good luck, i hope this helps.

Older VW's and Audi's are notarious for this type of behavior. You actaully need a Vag or good diagnostic tester to tell you which plugs are mis-firing. You will need to replace a coil-pac or two. VW's issued a recall notice about 3 months ago about this issue and intends to re-imburse owners on certain models and years for coil-pac repalcement. After market coil-pacs should cost less than $50.00 each. Hope this helps.

When and how to change spark plugs for 2002 saturn vue v6?

check timing belt!! good luck!!

the plugs on those engines are located under the center of the top pan , there should be a few bolts holding it in . the top of the engine is the coil its self and it directly contacst the spark plugs underneth i hate those engines

Non-start situations basically boil down to two things: No Fuel, or no spark.

I you are looking to throw a part at it, start with the crank sensor. They are cheap and not too hard to replace.

A full diagnostic approach would be to determine if it was a fuel or a spark problem. Check fuel pressures with a fuel pressure test guage: Low fuel pressure indicates a bad fuel pump or a bad fuel presssure regulator. Lastly on the fuel side, check t see if the injectors are getting a signal to fire, usually done with something called a noid light, I believe.

Spark diagnosis begins with first determining the condition, then finding the cause. Bad coil, loose wires, even the crank sensor are all suspect. A good repair manual with a flow chart is probably the best procedure to follow.

In my case, my manual only had a passing reference to the crank sensor and no diagnostic procedure to test it or even lead me to it. I found the solution through extensive web searches. Once I replaced it, all was well.