97 caliver p0300. Cant go over 20 mph. Very bad misfire. Every cylinder passes drop test by unpluging injectors and spark plug wires. Fuel press 55psi new wires plugs changed coil packs check firing order 210 - 215psi in all cylinders all pass leak down test

Misfire in cylinder #6. Could be bad spark plug, spark plug wire, cop coil, bad intake/exhaust valve, clogged fuel injector or piston/cylinder problem. What's the year, make, model, engine and have you been following the recommended maintenance schedule for new plugs?

P1189 Buick - Engine Oil Pressure Switch Fault PO301
Possible causes
- Faulty spark plug 1
- Clogged or faulty fuel injector 1
- Faulty ignition coil 1
- Fuel injector 1 harness is open or shorted
- Fuel injector 1 circuit poor electrical connection
- Ignition coil 1 harness is open or shorted
- Ignition coil 1 circuit poor electrical connection
- Insufficient cylinder 1 compression
- Incorrect fuel pressure
- Intake air leak
PO300 is just telling you that you had a misfire.

HARD TO SAY WITH OUT BEING THERE BUT THIS MIGHT HELP .
Crankshaft sensor Was the trouble with my 99 Chevy truck after replacing many components like coil cap rotor wires and so on .
http://www.obd-codes.com/p0102 Code P0300 Causes and Fixes Code p0300 is a code that is generated when your engine has a misfire that is not related to only one cylinder. Sometimes this code will be set in addition to other codes such as p0301 which means that there is a misfire on cylinder 1 (cylinder 1 is the number one cylinder when looking at the firing order. It is generally the forward most cylinder on the engine.). If these engine codes are present as well the you should diagnose those first as they are probably causing code p0300.
This code will set your check engine light and needs to be fixed as soon as possible. If it is not then you will probably need to replace your catalytic converter as well as the problem that is causing your misfire.
There are many causes for this obd code. Since it is a "random misfire" or "multiple misfire" this means that the misfire is on different cylinders and not just one all the time.
Common Causes

• Low Fuel Pressure
• Vacuum Leak
• EGR system malfunction
• Internal Engine Problems (such as low compression)

Less Common Causes

• Faulty Coil
• Faulty Spark Plugs and/or Wires
• Camshaft or Crankshaft sensors
• Ignition module
• Computer

code p0300 refers to random/multiple cylinder/s--misfire detected===causes--spark plug/s--HT lead/s---injector/s--ignition coil/s---low compression---wiring. Most of your mates will tell you to replace the plugs and leads and that may fix it but injectors are a major fault in misfires. So have a pressure test done on the fuel manifold first and check the fuel pump/pressure regulator/filter. If the pump is not producing fuel or the regulator is set too low then the injectors will not deliver the fuel at the correct amount at the right time (misfire- random cylinder). Plugs and leads will cause a constant misfire not every wherever cylinder.

okay there are a few things that need to be checked here, seems like you were testing the wrong things, lets start with the po300, this code is for a misfire a random one which means any cylinder at a certain time has misfired which is due to the next two codes listed, the po014 which is the exhasut camshaft postion sensor system performance and the po201 injecotr control circuit for cylinder #1.

Have the injector ohm ed and the connection and wiring checked, this problem may be a bad injector or wiring to cyl # 1 and the cam sensor needs to be tested also on bank 1exhaust side. good day

A code P0300 may mean that one or more of the following has happened:
Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer

Possible Solutions:
If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

Hope helps.

P0203 - Injector Circuit Malfunction Cylinder 3

Powertrain Control Module (PCM) or Electronic Control Module (ECM) checks the injectors circuit resistance and monitors the voltage drop during normal operation. The PCM/ECM will trigger the P0203 code when the resistance or voltage drop at the injector #3 is out of specifications.

Causes:
- Open or shorted wiring harness to the injector #3
- Bad injector #3
- Bad PCM/ECM

Solutions:
- If damage, repair injector wire harness or connector
- Replace injector
- Replace PCM or ECM


P0204 - Injector Circuit Malfunction Cylinder 4

Same info as the P0203 DTC


P0300 - Random/Multiple Cylinder Misfire Detected

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crankshaft position (CKP) sensor (POS) signal to vary, Powertrain Control Module (PCM) or Electronic Control Module (ECM) can determine that a misfire is occurring.

Causes:
- Improper spark plug
- Insufficient compression
- Incorrect fuel pressure
- The injector circuit is open or shorted
- Fuel injectors may be faulty
- Intake air leak
- The ignition signal circuit is open or shorted

Solutions:
- Perform Injector Service
- Replace Spark Plugs
- Replace Injectors
- Replace Ignition Coils

Hi, multiple cylinder misfire, is when the engine cylinders do not fire in the correct order, and do not do it constantly. There is no particular pattern to it. My experience with this condition is that it is usually caused by a faulty ignition coil that is beginning to burn out. It could also be bad wires pluds rotor or cap

Causes Include.

• Faulty spark plugs or wires
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector(s)
• Burned exhaust valve
• Faulty catalytic converter(s)
• Stuck/blocked EGR valve / passages
• Faulty camshaft position sensor
• Defective computer

Possible Solution:
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
Random misfires that jump around from one cylinder to another. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

I'd have fuel pressure checked, and at the very least, replace fuel filter. Not unusual to get multiple misfire codes due to low fuel pressure, thus starving cylinder(s), and causing the misfire code(s).

P0300 Random Misfire

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.

A Random Misfire code usually indicates a vacuum leak or bad gas.

NOTE: If a misfire in a specific cylinder should lead you to check the spark plug, fuel injector and compression.