code p0300 misfire

[1997SEgreenmonster]

So i took my car to the dealership to try and figure out this the whole stumbling and hesitation problems. The only thing they could tell me was it was a random misfire in all cylinders and the only thing they suggest is that i get a fuel system cleaning done by them which cost $190.00 ...... So i dont know what to do i told them what all ive done to the car and thats all they could give me.

[Alpine_jake]

Found this on another forum

Causes
A code P0300 may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor
Faulty fuel injector
Faulty ICM
Burned exhaust valve
Faulty catalytic converter
Running out of fuel
Poor compression
Faulty MAF
Defective computer

[richardg]

Yep it could be any of those. Time to start checking 1 by 1. Odds are it's one of the easier things but you never know until you start looking. Most are fairly easy to check yourself...

Spark Plug: Pull the spark plugs and see what they look like ( if they look horrible then replace as needed. Check after you replace that 1 thing!)

Wires: You can buy a spark plug tester (http://www.amazon.com/KD-Tools-2757-Cal ... ire+tester) to see if it is sending spark down.


Coil Pack: with the car running (carefully! and with rubber gloves preferably) pull the wire from the coil pack see if it sparks like hell or not.

O2 Sensor: Get a OBD II scanner than will show live data. Check the O2 Sensor. Voltage should bounce all over the place between 0.001 and 0.999. If it doesn't (remains constant or no voltage at all) replace as needed. There are 2 sensors to check usually (1 before the cat and 1 after)

Fuel Injector: They don't usually go bad but they do get clogged. I don't use those cleaners that you put into the system; I just pull the rail and clean it usually but that's because I like to DIY work on cars and look at things.

ICM: "ignition control module" well this is under the coil packs (there are 3 coil packs 2 wires/pack) I don't have an easy way to tell you to test this but if the packs are not firing and you replaced them (as they do from time to time) then you could replace it.

Exhaust valve: Don't try to test this yet... get back to us after doing the "easy" tests :p

Cat: This is a simple test buy you need a tool to check for air flow. IDK you may just bring that in to an exhaust shop and have them test it for you. You would need to drill a hole before and after the catalytic converter and measure air flow to see if it is clogged.

Running out of fuel: Sure. Well see if you have pressure in the line first. You can usually rent this tool.

Poor compression: Same as above^^.

MAF: "mass air flow" sensor. Usually just needs to be cleaned

Computer: SOL :p if it has gone bad.

IDK maybe someone else can chime in here and give more input. Best of luck. Also check vacuum hoses and standard maintenance PVC and such (always a good idea)

[1997SEgreenmonster]

So i was thinking i didnt have this misfire till i put the new plug wires on the car from napa them belden wires. Im thinking bout pulling them and going back to delphi wires casue im sure i didnt have this problem.

[richardg]

before you change them back you can check them to make sure. yeah I hear what you're saying. get a good brand of wire! let us know. best of luck!

[1997SEgreenmonster]

Okay so i still have a really bad hesitation. I cant get this figure out im go crazy. CAN ANYBODY HELP ME OUT OR GIVE ME ANY OTHER THINGS I SHOULD TRY IM GOING CRAZY I CANT GET THIS PROBLEM SOLVED?????????

[Rogue]

If you just changed the wires and not the plugs you should look at your plugs. Pulling the wires (especially old ones) can cause cracks in the plugs that will cause misfires.

[Trinity]

If this is seen in conjunction with a P0113 the IAT sensor can be the issue as well.

[1997SEgreenmonster]

well last night my SES light came on when i was driving on the highway stop at a autozone they pulled a code for a misfire in cylinder 1 so im going to pull the plug today.

[loudog1972]

When I got that misfire I had to replace my lower intake gasket. there was a very small in the front of the engine. Found it by spraying carb cleaner around all the mated surfaces cars been great since.

[Bonny77]

Well looks like I'm in for lots of fun Took mine to dealer, they replaced 1 coil pack but did not solve the problem. Told me for another $350 they would change the module. So I'm planing on doing it myself for $146.00, but now I see all these other posibilities as cuases. They told me at the store that it would be OK to return the module if it did not solved the problem. Update follows...

[Bonny77]

Well, I pulled the spark plug wire one at a time off the coil packs. 2 of the 3 sparked (use rubber gloves or you will feel it).
I took the module off, took it to Advance Auto and they checked it. It tested bad, they tested a new one and it tested good.
So after $124.00 for the new module, Bonny is running with power again. Now I have to fix a cooliant leak from the heater
elbows to the tentioner. Anyone has done that?

[Trinity]

Well, I pulled the spark plug wire one at a time off the coil packs. 2 of the 3 sparked (use rubber gloves or you will feel it).
I took the module off, took it to Advance Auto and they checked it. It tested bad, they tested a new one and it tested good.
So after $124.00 for the new module, Bonny is running with power again. Now I have to fix a cooliant leak from the heater
elbows to the tentioner. Anyone has done that?

Yup, do a search here and you will come up with many sources on changing the elbows. Make sure you get the aluminum ones as they last better. You can get them at many places including O'Reilly.

Here's a link to them at Intense..

http://intense-racing.com/Merchant2/mer ... URED_ITEMS