ENGINE MISSING on #4

[herebyproxy]

4.0 OHV

Code 0304

Have changed plugs, wires, coil pack, cleaned MAS, replaced fuel filter, cleaned throttle body, run gas treatment through the fuel, vacuum is steady except when 4 misfires is a tiny deviation (less than 1 point) ......I guess all that's left is the fuel injector....

agree? disagree?

 

[2000StreetRod]

check compression

You may have a blown head gasket, cracked head, broken or weak valve spring or bad valve.

 

[bigcrunch]

Do a compression check on #4 and cylinder next to it.

 

[herebyproxy]

Oh...I did have a check for a leaking head gasket, too (negative)

You're right, sometimes a vacuum check doesn't tell the whole story....will do a compression check next

Thanks guys....I'll let you know

 

[herebyproxy]

Compression seems to be within tolerance

#4-147 lbs
#5-160 lbs
#6-150 lbs

4 is a little low but not low enough to misfire I don't think

whatcha think?

 

[bigcrunch]

a little low, you check it cold?
try this let it it warm up with the radiator cap off, watch for bubbles if they are there head gasket leaking to collant passage. if none probably injector.

 

[herebyproxy]

I did check it cold......I already did the head gasket leak test....negative

I'm still thinking injector, too...

Thanks

Any other thoughts? anyone?

 

[Robert Nick]

Exchange the Injector from #4 to next closest Injector and see if the Miss moves to that location. That would confirm your thoughts.

 

[herebyproxy]

I'd like to but the injectors are a little over my head when it comes to mechanical skills......The throttle body and fuel rail have to come off and I don't have the resources for that....

Thanks...

 

[2000StreetRod]

fuel injector cleaner

Your compression looks OK. When your fuel tank level drops to half full add a bottle of Techron fuel injector cleaner. It can take 200 miles to work.

 

[herebyproxy]

Already did that....in fact it was the first thing I did along with cleaning the throttle body good....

Thanks...

 

[herebyproxy]

Thanks guys...

All the problems were a faulty plug that looked just fine.....put a set in and it's fine now.....I didn't realize a plug could break down and not be cracked or some other telltale sign.

 

[herebyproxy]

Another update

Looks like I have a cracked head somewhere around the number 4 cylinder. It's not a major issue as I can continue to top off the coolant and put a new plug in the number 4 position each time the insulator cracks and causes a misfire. From my experience and what I've read, the plug will go each couple of months. Since I am on a fixed income and new heads are not in my budget.......well...you see why it's more of an annoyance than something serious...lol

Thanks for all the suggestions......