Misfire in '05 Ranger

[6herald6]

A scan of my '05, 3.0L Ranger came up with the following codes: P0300 (random misfire detected), P0304 (cylinder 4 misfire detected), and P0316 (engine misfire detected on startup).
I put in a new coil pack but the problem is still there. What else should I check?

Fred

 

[adsm08]

Plug, wire, injector, in that order.

 

[6herald6]

Thanks, Tech. I hear I might need to do a compression test too.
Fred

 

[d_man1]

I hate to say it but... Fix it asap before all pistons "misfire." I did the job myself. It is not an easy job as you need to replace both heads... yes I said both heads. why? Because ford engineers are lame and decided to not use hardened seats on the valves! Normally the exhaust valves are the first to go. If you catch it early enough they can machine the heads valve seats and add hardened seats. If the recess is far to large, they cant machine the heads as if they do they will cut into the coolant channel. Does it suck? Yeah. Mine started with a weird clicking noise when I would "open" up the engine on uphill climbs. I am the Orig. owner, with 119,000 miles on it at the time. I replaced so much shit before I found out it was the valve seats. and around 125,000 almost all the valves had a bad recessing problem. fit it ASAP before you have a dud

Good luck, and If you feel you have the skills to replace them yourself, good luck also

 

[JP02XLT]

Do A compression check along with adsm08's advice on plug, wire & Injector prior to pulling the heads, a miss is not always a cylinder head problem, I had a miss on mine, only on high rpm and under load, it had a new coil, plugs, MSD 9mm wires, injectors checked etc etc, and a compression check, all cylinders 180 psi. It wound up being ignition arc (only under load) from the plug boot to the header tube, as they are closer proximity to the header tube than when using exhaust manifolds, I found it by closely looking at the header tube (stainless) and it had a tiny black dot on it, I had to double boot it to stop the arcing. So before you pull the heads looking for a cracked seat, spend some quality time trouble shooting.

JP02XLT

 

[6herald6]

I think it could be a the simple wire, plug, and injector problem. Before I could get to checking the problem out a couple of years ago the problem went away for about a year. No Check Engine light, no rough idle. Then the problem reappeared 2 weeks ago. It wouldn't seem to be a bad seat problem because that kind of problem does not come and go. It comes and stays and maybe gets worse.

Fred

 

[6herald6]

Well, it's starting to look like worse case scenario. #4 plug fires steadily, according to my plug tester and #4 injector pulses steadily with a stethoscope check. Plug is bone dry when examined which tells me the fuel is being burned off with no combustion. Haven't done a comp. test yet.
Would a bore scope check be quicker and easier than a comp. test to verify a bad valve/seat and bad head gasket?

 

[stmitch]

Have you checked plugs on any other cylinders, or just #4? Your deductions seem logical, but I wouldn't automatically assume your valve seats are toast because of a misfire code and dry plug.
Misfires can be tricky to find, because there can be several causes. The valve seat issue isn't very common compared to plug/wire/coil/injector/fuel quality issues. The plug could be dry because it's not getting fuel. I've had 3 injectors fail in my 00. I know that you heard it switching, but that doesn't mean it's not clogged. Perhaps there is an abundance of carbon buildup in the chamber? The 3.0 is known for developing lots of carbon.
As you said, a compression test should reveal if there's significant mechanical damage, so it doesn't hurt to check, but the valve seat being the culprit isn't all that common really.

 

[Rearanger]

Would a bore scope check be quicker and easier than a comp. test to verify a bad valve/seat and bad head gasket?

No.

 

[Rearanger]

The 3.0 is known for developing lots of carbon.

Side question off topic: How do you clean your cylinders of carbon?

 

[stmitch]

Side question off topic: How do you clean your cylinders of carbon?

There are several decarbonizing products available. SeaFoam is the most common one, but I've had good experience with a similar product from BG too. Put some in the intake manifold vacuum line while the engine idles, and then put the rest in your fuel tank. It will clean the cylinders, and your fuel system.


If your truck is flex fuel, I'd skip the AutoZone specialty stuff, and just use e85 for a tank or 2. It's typically cheaper and more difficult to screw up. If you go this route, and you've never used e85 before, I'd phase it in slowly by mixing with regular fuel first. Switching to a full tank of straight e85 can clean too well too quickly, and cause injectors to get plugged with the junk being cleaned from the system.

If you ever have the engine apart, I'd definitely suggest doing some grinding/polishing on the combustion chambers to eliminate the roughness of the castings. This will help avoid pinging/detonation in several ways. Eliminating the roughness reduces the small peaks that can act as "hot spots" and cause preignition, it gives the carbon fewer places to attach, which reduces the buildup, and it also very slightly lowers the compression ratio, which again reduces preignition/pinging.

Here's a before/after to show the rough stock castings, and what I did to try and improve the situation:

 

[6herald6]

The original scan showed a misfire in #4. All plugs fire. Injectors 1 through 4 pulse. Unfortunately I can't check injectors #5 and #6 because they are hidden behind the upper intake manifold.
Ok, maybe the one injector could be blocked. I'll try and remove and check it out. In the meantime I have been running injector cleaner in the tank.

 

[JP02XLT]

A 25-30% ratio of ethanol / gasoline works great for injector, carbon cleaner, I run it in all my vehicles and have for years with no problems other than less mpg on that tank of fuel. once per month or so does wonders

JP02XLT

 

[6herald6]

One more thing I forgot to mention earlier. This truck does not like to idle too long. If I'm in very slow traffic or stopped at an intersection for a few minutes the "check engine" light goes from constantly being on to flashing. When that light starts flashing the idle gets very erratic and the engine wants to stall. I thought this was only happening in hot weather at first but happens in cooler weather as well.
Is this happening because it's running on 5 cylinders?

 

[6herald6]

One more thing I forgot to mention earlier. This truck does not like to idle for long periods of time. When I'm in slow traffic or stopped at a traffic light for several minutes the "check engine" light goes from constant on to flashing and the idle becomes very rough and the engine wants to stall.
Does this happen because of the misfire problem or is it another problem?