P0306--Misfire error is giving me Groundhog Day trouble

[spakack]

Lets start from the beginning. My truck started acting sluggish and at a stoplight would idle very ruff. I changed the plugs and it seemed to do the trick. It would do it intermittently for a while. But then it just ran poorly all the time. Finally the check engine light came on and the code was a misfire on cylinder 6. I then replaced the Wires and coil pack based on what I could drum up from the Internet. My friend who helps me with all my automotive help tries to make sure none of the injectors wires are unplugged or compromised. I then picked up a compression tester and checked the engine and on the opposite side the pressure was all very close and normal. On the cylinder 6 side the other two cylinders besides the number 6 was lower. But all were lower that the other side. I replaced the head gasket all around and that did nothing. It still runs ruff but no check engine light has come on. I'm guessing because the power to the computer was cut.
I kept reading the net hoping that a known problem existed. I kept reading about heads getting replaced because the valve would get messed up. I thought it was worth a shot so I got some new heads and replaced them both and nothing changed. I'm almost at the point where with a few new parts I will have a new engine. I'm turning to you guys for help. I really don't care if my problem ends up being a $2 part I just want my truck back..

 

[Wicked_Sludge]

wow, you replaced the head gaskets, and then the heads without properly diagnosing the problem? it really pays to properly diagnose something the first time rather than throw parts at it.

i would start with simple things like checking for vacuum leaks and taking an OHM meter to the coils. you might also try switching coils and injectors between cylinders to see if the miss follows a particular coil or injector.

btw these are all FREE test.

i sure hope you dont end up having to tear the engine back apart a 3rd time to properly fix the problem

 

[spakack]

When I replaced the head gasket the first time I moved the fuel injector from one side to the other so I could get easy access to it and to see if the problem went with it. I havent got a missfire code to read because I havent been driving it. Where can I get all the Ohmm specs for the engine?

 

[almostclueless]

You really just might save a lot of money if you pay the 60 bucks or so for a dealership to find the problem....

 

[Wicked_Sludge]

a chiltons manual would probably tell you. auto zone's website also has sort of an on-line chiltons manual that might have the info. if nothing else, your local for dealer would rpobably look it up for you for free.

 

[betomonroy]

Just one guess:
CKP
Crankshaft Position Sensor.

 

[spakack]

About 6 months before all this started happening I had a miss fire on the opposite side that caused my engine to run ruff at lights but I did what I could and replaced the IAC valve and the wires back then and the code never came back. The engine never had a loss of power when driving. It just ran like crap when sitting at a light. When the engine started giving me trouble the engine ran like crap and had no power. I am going to be doing another compression test in the next few days. Is there anything that would cause a severe timing issue that could only show a code on one cylinder? Its possible I could have had bad valves in combination with bad timing to create what I have now. Or something worse.....

 

[betomonroy]

A broken Crank CKP ring or a bad CKP can cause this situation as well as a bad cam sensor (whe equiped). But the most radical approach (if none of the avobe is) will be the ECM. Good luck man.

 

[FordBoy]

hey spakack, i had misfiring troubles and backfiring and loss of power and rough idle. talked to 6 mechanics they all said it was probably the computer or a computer ground that rusted out. turned out it was a dirty mass air flow sensor i cleaned with a bottle of mass air flow cleaner from Gunk. if you had a aftermarket filter on your intake the oil from the filter can plugs up your mas. i dont know if this is your problem but good luck hope it helps