P0304 Cylinder 4 Misfire - Headgasket Replacement

easiest thing to do to rule coil out, swap it. if the problem moves, most likely its the coil. and water usually doesnt settle in the oil. it makes a milkshake.

 

i mean swap it with the one next to it. if you swap 3 and 4, and p303 is now code, bang, replace the coil.

 

You could pick up a combustion leak detector to test for a HG problem too. https://www.walmart.com/ip/Lisle-Co...39785&wl11=online&wl12=19654714&wl13=&veh=sem

 

Take the plug out of #4 and crank the engine until you can see the piston with a flashlight. If that plug is cleaner than the rest, and you can see a shiny clean piston, that could indicate a coolant leak from the head gasket into that cylinder. Definitely more common in early models, they changed the gasket in later years. A compression test is a good idea and if it is the head gasket you'll also end up with a cyl 6 misfire. Definitely move that plug and coil to a different cylinder and see if the miss follows. You'd have to have an insane gap much greater than .06 to get a miss.

 

Trying to minimize effort and time (raining a lot over the weekend), I put in a new coil two days ago rather than swapping. Still threw the code at third start up. Put the new plug-in yesterday, so far no code but since the codes have been intermittent, I'm not confident it's not going to reappear.
Since the coolant is red, does that mean the milkshake is strawberry flavored?

 

Problem with this test is I have read a few posts where the engine passed this test and it still ended up being the head gasket

 

Cool, thanks for your thoughts. When I changed the plug yesterday, the piston was near the top of the engine where I could see it with the flashlight, it did not look clean. Not tons of build up, but a little. Plug did not look clean, rather it just looked normal wear and color to me. I can take a picture of it when I get home. As far as the .06 gap, that's pretty much what I was thinkin. Do you think it's worthwhile to reinstall the old coil and old spark plug into a different cylinder to see if it codes? I have a theory that the new spark plug is temporarily preventing a misfire but did not solve the actual problem... would an oil analysis from Blackstone confirm conclusively that I have a HG problem if they find even trace amounts of coolant? And if they don't find any coolant in the oil, would it prove conclusively that I do not have a head gasket problem?

 

You must do the compression test, it will let you know if its mechanical or electrical problem.

 

Well the #4 misfire came up again, even after coil and plug change. Ran injector cleaner through the system, with no change. That leaves me with either injector or HG, correct? I plan to run compression test once the rain stops probably Thursday or Friday, will post the numbers. Is there reason enough to suspect injector to swap injectors from cylinder to cylinder?

 

I would try moving the injectors.

I had a 1997 V6 years ago that threw a cylinder 3 misfire one day. Engine would stutter going down the highway and idled terribly. I had changed plugs, coils, and my mechanic at the time thought I could have a valve out. Point is, I took it to the dealership for a diagnostic and when I went to pick it up the code had moved from cylinder 3 to cylinder 1. I asked the service manager what happened because I knew the code started in 3. Said they moved the injector and that it went to 1. I stopped by the part store on the way home and swapped the injector out for a 1/4 of the price the dealership quoted me. Try moving the injector, I might not have ever needed the coil I replaced on it.

 

Interesting, thanks for the input. I'm trying to avoid too much testing, but going after the head gasket looks to be a pain so I better do my best to confirm first, I just hope I am I'm not hurting the engine driving it in the meantime. Either tomorrow night or this weekend I plan to switch injectors, replace remaining plugs, compression test, clean throttle-body and mass airflow sensor, and replace the two vacuum hoses. Without another direction to go in if that doesn't help or confirm anything, I suppose I will just rip apart my engine and go after the head gasket. It's going to be fun this time a year with no garage...

 

If you have a steady miss and flashing CEL then you could be damaging your catalytic converter. Because the miss stayed after swapping the coil and plug you can be, sadly, all but certain you have a HG leak. Do a compression test to be certain; I wouldn't do anything before that at this point. It's likely simpler than getting the fuel rail/injector out to swap anyways.

 

Just had that code a few days ago, coil pack fixed it for me. I have an 05 with 145k on it. Prob gonna replace rest of the coil packs to be safe

 

My misfire seems to becoming more steady at nearly every start up now. No misfire while driving though. I'm afraid you might be right about the cat, I am consistently getting P0430 code now and the injector cleaner is long gone.

Nice! I seem to be one of the unlucky ones. I had my fingers crossed when I changed my coil pack, but no such luck for me. Before changing all your coils out, you may want to give your truck a week or three in case the code comes back. Mine was very intermittent at first, and only sometimes triggers the light. Code shows up on my reader long before the light turns on.

 

I think I heard bubbles/water moving under my dash on my way home. Exciting.

 

Ok, I'm going after it today. I pulled the spark plugs with some interesting results, see picture attached. #4 plug looks cleaner and brownish when compared to the other five which all have black burn marks and are more grayish in color. As far as gapes go, #1,#3, and #5 were all 0.059. Driver's side however... #2 is at 0.055, #4 at 0.061, and #6 at 0.060.

To me, this all but confirms my initial dread that it's my HG. I'm about to compression test to confirm before I start taking things apart. Any tips or strategies for head removal that come to mind would be appreciated!

 

Need a special socket to remove the head bolts.

 

I removed all plugs expect #4, removed ignition fuses, filled radiator to the top, and had my girlfriend step on the clutch and gas while cranking the engine. Coolant slowly rose as the engine was cranked. Afterwords I removed #4 plug and could see fuel or coolant in the cylinder while the others were dry. The new spark plug was also wet, looked like black moisture. Feeling fairly confident it's time to start going after cylinder head removal. Thinking I will replace o2 sensors, all gaskets encountered, have the head cleaned, checked, new valve seals, new oil pump, chain guides, head bolts, idler pulleys, water pump, pulley belt, special bit for head bolts, oil of course w/filter, new plugs, radiator fluid, and fpig sealant. Thoughts on my list? I plan to leave engine in and oil pans on and clean everything along the way.

 

Lot of brake clean and razors or other tool to remove the old gasket material.

Lots and lots of pictures.

New o-ring between bottom of timing cover to oil pan, and timing cover to driver side head.

 

Oh yeah, pictures! Doing my best to label and stay organized as I go, but promptly starting taking pics when I saw your post, thanks for reminding me. I'm hoping the master gasket set has the rings but I'll double check. Adding thermostat to the list.

Pics is where I got after day 1 before I met my quota of f****** plastic clips. Radiator was the worst part so far, the mounts were frozen and I had to break 3 of the 4 bolts to get the thing out. Still have the crank pulley to do, and the exhaust manifolds look like they are really gonna be a pain.

Interesting to note in the picture that the drivers side seems to be noticeably darker. Has me a bit concerned the right side got oil starved.