Replaced SOLENOID VALVE now have P0307(Faulty Cylinder C-Misfire Detected) HELP!!

[Anthony]

Hey guys, Please help me out with some info on what to do next!

So I was driving the Hoe yesterday and my check engine light started to "blink".

Question:
I replaced that SOLENOID VALVE fine, but now I was driving today and my check engine light Came on and I ran the check tool and The code was:
P0307:Faulty Cylinder C-Misfire Detected (Cylinder 7)

What would cause this? Could it be related to me changing that other part yesterday?

For what I have done already to fix/resolve issue
The 7 cylinder is the one in the farthest back on drivers side near the firewall correct? I did all this work to this one and 5 next to it.
1) Switched spark plug wire from 5 to 7 to see if issue moved to 5, it didnt.
2) Switched the coil from Cylinder 7 to 5 to see if issue moved to 5, it didnt.
3) Took spark plug out of Cylinder 7 and it looked fine and no major issue with it.
4)Today I had about 1/8 tank gas so I put 10 gallons of Super+ Gas in and a full bottle of STP Complete Fuel System Cleaner and am going to run the Tahoe to see if it resolves the code.

If the code doesn't go away after this, what steps should I take next? Replace the Fuel injector for cylinder 7?

Thanks in advance for help and Ill keep this updated so if anyone has same issue!

-Anthony

 

[Rivieraracing]

I don't know the cause of the code but I would swap the spark plug with another cylinder's spark plug and see if the code follows or completely disappears!

 

[HMFDZ28]

Usually if the CES light is flashing you have some major issues. The Knock sensors are running angry.

I wouldnt swap from one cylinder to another.... Thats not gonna help ya all that much. A weak coil pack maybe fine at low RPM but dead higher in the powerband. Plus you just asking for trouble. Unless the PCM see's X amount (dont remember accual number) of misfire's or The Knock sensors are picking up the excessive knock... she aint gonna flash the CES.

What Solonoid Valve are you talking about?

 

[Anthony]

Usually if the CES light is flashing you have some major issues. The Knock sensors are running angry.

I wouldnt swap from one cylinder to another.... Thats not gonna help ya all that much. A weak coil pack maybe fine at low RPM but dead higher in the powerband. Plus you just asking for trouble. Unless the PCM see's X amount (dont remember accual number) of misfire's or The Knock sensors are picking up the excessive knock... she aint gonna flash the CES.

What Solonoid Valve are you talking about?

The Solenoid valve is used in rear new the gas filter and helps get rid of excess fumes in the tank. Mine was clogged so I had to replace it.

So your suggesting that I buy new: SparkPlug, SparkPlug Wire, and coil and replace all of 7 to see if it makes a difference? Do you know how to replace the fuel injectrors because that was the next step I was looking at to cure this problem. Thanks!

__________________________________________________________________________________________
**Update**
Today I ordered a new Fuel injector off eBay for $25 shipped (Advance Auto was $130) and it should be here later this week and Friday I am going to replace the Fuel Injector on Cylinder 7 with info provided on chiltonlibrary.com and I will post back if it cures the issue.

I still do not consider this to be "fixed" so if anyone has insight or a suggestion PLEASE POST IT

Thanks,
Anthony