PCM code P0306 and P0175 together what can cause both these code at the same time?

SOURCE: EGR Valve and Cyl. 5 misfire.....???

Hi

If this is an electronic EGR valve which is opened and closed by the PCM, then it may simply have to relearn the fully closed setting for idle, and it can sometimes be done by switching off the ignition, disconnecting the wiring plug from the EGR valve, and then resetting the fault codes with a scanner.

Now here's the important bit, the very second the scanner tells you the fault codes are cleared, quickly switch off the ignition. This will prevent the PCM from setting another code.

You can then reconnect the EGR valve and hopefully the lesson will be steadfast in the PCMs memory!

As for the cylinder 5 misfire, if it is still misfiring then you need to check for spark, fuel, and compression in that cylinder.

Run the engine for a minute and then whip out the no.5 spark plug. Is it dry or covered in fuel? If its covered in fuel then you have a spark problem, and if its dry then you have a fuel problem.

If its a spark problem and the plugs each have their own coilpack, then it is very highly likely the coilpack at fault, and in which case it is best to fit a new plug as well as a coilpack.

If its a fuel problem then it is very highly likely the injector at fault but you should check for a supply and earth pulse at the injector before condemning it, because sometimes the injector loom becomes crimped and damaged.

It could be a compression problem, but I doubt it, however, just to be safe you may want to carry out a compression test on that cylinder before throwing parts at it.

An easy way of determinig injector and coilpack faults is to move the suspect part onto another cylinder and see if the fault code follows it. If it does then you know that component is faulty.

Regards

Geordie

SOURCE: diagram for replacing distributor, cap, rotor...

Replace the coil. It is shorted out. I have changed quite a few coils for the exact same symptom.

The graciousness of a FixYa rating for my assistance would be appreciated.

Thanks for choosing FixYa for assistance.

SOURCE: 1989 GMC 2500 5.7L - engine surges and stalls at idle. Loses power at cruising speed.

Wow you have replaced a lot of stuff. Lets go back to the Fuel pump. When you replaced it did you replace the hose between the pump and the sending unit. These are common for splitting. Have you hooked up a fuel pressure gauge to check what pressure you have? It should be real close to 13 psi and should raise to at least 18 or 19 when you pinch off the return line.

SOURCE: 2005 F150 runs rough, back fires a little, has

Sounds like MAF(Mass Airflow Sensor).

SOURCE: 1991 cadillac deville fwd 4.9 engine shudders hard

I have a 1991 Cadillac Fleetwood 4.9 120000 miles, I have the same problem. replaced plugs,wires,cleaned throttle body, and O2 sensor and have same problem. Taking it to a GM shop on 02/24/10.