Hesitation issue, car running poorly p0300, random misfire

Mine had a bad connector on the injector.. replaced it and she runs like new

I have been having this problem for quite some time and I can't seem to nail the cause down. I have a lack of power and I can get my CHECK ENGINE light to come on every day if I want to. Every once in a while it would be for a specific cylinder but 95% of the time, I get the code for random misfire. So far I have changed:
Spark Plugs (twice)
Wires
Ignition Coils (all 3)
Ignition Module
MAP Sensor
Air Filter (twice)
Fuel Filter (twice)
Fuel Pressure Regulator

I have also checked and verified the fuel pressure is correct.

Are there any other sensors that may cause this code and engine performance?

Any help would be greatly appreciated.
Thanks

My next step would be a compression test and then checking the injectors
try and have the fuel injectors clean

Would dirty or clogged fuel injectors cause misfires? Do you know what some other symptoms would be for bad injectors. Would a fuel injector service at a local repair shop clean them if they were clogged or would they need to be replaced?

Should have the injector cleaned for sure
but the service should be to isolate and clean the injectors and not just add some cleaner to the tank, as you can do that your self
special top cylinder and fuel injector cleaner should be used
as recommended by the factory



also check this if it apply to you
STB

General Motors Engineering, in an effort to determine the root cause of catalytic converter damage, has determined that aftermarket alarm systems incorrectly installed in vehicles have the potential to cause misfire codes and damage to the converter. These alarm systems use a circuit interrupt which utilizes the ignition circuit on the vehicles.
These alarm systems utilize mechanical relays and normal vehicle movement can trigger these relays to engage and disengage the ignition circuit while the vehicle is in motion. These disruptions of the ignition circuit, which occur in milliseconds, may cause more fuel to be commanded. Over time, this dumping of fuel on and off again can cause misfire codes and ultimately damage the converter assembly.

My #2 cylinder is misfiring. I have spark at the spark plug, however when i pulled the plug i noticed it was white as if it was getting no fuel. i changed the fuel injector and the ignition module, still nothing. i checked the compression and it is fine. The engine runs but the #2 cylinder wont fire.

If fuel pressure is good, then check that injector is firing, if you remove the connector and there is no change in the engine, then injector is not firing.

If SFI injection, check fuse for that injector.

the engine runs fine but that injector wont fire. i read the manuel and it looks like the fuel injectors all go to one fuse which is still good.

A simple tool called a Noid light can tell you if injector is firing. They are available in sets at most autoparts stores for $20.

Remove electrical connector to #2 and connect noid light, crank engine, if light pulses, then injector or fuel, if it does not pulse, the PCM, Fuse, or injector, or wiring.

There is a misfire on cylinders 1 and 4 and they share the same ignition coil. I unplugged the ignition coil for those two cylinders and it had no spark. I unplugged the others and they had spark. I replace the ignition coil but that did not solve the problem and I also replaced the spark plugs and wires. I then tested the ignition control module pins that go into the ignition coil and I have around 12 volts on 1 pin and less than 1 volt on the other pin. I cannot figure out the problem and I really need help.

the module has failed. replace it

Roy

Thank you

1996 Pontiac Grand Prix 161200 miles (bought new - great car)

Codes are showing a multiple cylinder misfire. Engine seems to run fine until you start to go up hill and it is under a load. At that time the car jerks and you can tell it has a bad miss. If you go down on the accelerator it clears up. I had a mechanic to replace the intake gasket and the EGR valve last year. It was doing this before and after the gasket was replaced.
I took it to another mechanic this year and he said the intake needs to come off and clean the carbon out of it.?? He sprayed some type of cleaner into the intake and it did seem to run a little better for a day or two.
The service engine light is on. Car starts fine and seems to idle ok.
Got any ideas??? Thanks for any suggestions you may have.

Rodie

Take car to some autoparts stores and get codes read.

If you can, check fuel pressure with mechanical gauge, and look at the fuel pressure regulator vacuum line for presence of gasoline.

Other than fuel and spark, you may have a clogged CAT or partially clogged.

[quote:81f2031ef9="mmprince4000"]Take car to some autoparts stores and get codes read.

If you can, check fuel pressure with mechanical gauge, and look at the fuel pressure regulator vacuum line for presence of gasoline.

Other than fuel and spark, you may have a clogged CAT or partially clogged.[/quote:81f2031ef9]

Ran the codes and it showed a EGR and a Caltylitic Coverter fault so I think you may be right.
I took the EGR valve off and blowed it out with air and it seemed to run a little better.
Thank you for you answer.

Thanks for using 2carpros.

Engine Performance problem
1995 Pontiac Grand Prix 6 cyl Two Wheel Drive Automatic

changed spark plugs and wires. still has engine miss and rpm surges and rotton egg smell. need to know location of bank 1 sensor 2 and will just a defective sensor create these problems?

Engine running rough or misfiring can be cause by the following: 1.Defective spark plug. 2.Inadequate spark/coil,defective spark plug wire. 3.Lack of compression 4.False air leakage. 5.Faulty fuel injectors. 6.Insufficient fuel pressure. 7.Contaminated fuel. 8.EGR valve that is leaking. 9.Oxygen sensors.