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I purchased a 2007 Ranger with a 3.0 v6 and it has two codes:
P0430 - Catalyst System Efficiency Below Threshold Bank 2
P0304 - Cylinder 4 Misfire Detected
Issue symptoms:
Obvious misfire during idle.
No misfire when driving
No misfire when holding throttle and keeping RPMs past any point beyond 1k RPMs
Low power going up steeper highway grades (since this is my first ranger I may be expecting more than it's capable of but when going up highway grades it seems to slow down quite a bit and I have to really give it some throttle to keep a steady speed up the grade)
Very rumbly sounding at WOT with poor WOT acceleration. Low end acceleration from lighter throttle stabs feels good and powerful though
intermittently noisy catalytic converter - sort of like the charcoal looking stuff inside it is broken up. I can only hear it sometimes but not always.
So far, I have done the following:
Removed the #4 spark plug and confirmed it was very white/dry. Meanwhile, removed #1 and #5 and confirmed they're a more golden brown color (as I would expect)
To rule out the spark plug, swapped #4 with #1 spark plugs
I replaced the coil pack
Replaced #4 fuel injector
Live O2 sensor data scan - Bank 2 Sensor 2 is clearly going up and down very frequently. Meanwhile. Bank 1 Sensor 2 is much less dramatically (i.e. B1S2 is quite smooth)
Overall, the engine runs really well while driving around town and even on the highway. The main issue is the misfire while idling and very rumbly sounding engine at 70-100% throttle that seems to makes more noise than acceleration.
I really hope the issue is just a bad cat and not something scarier sounding like a valve train issue.
I'm hesitant to remove the cat before I get confirmation since I seen it's a high probability of breaking the exhaust studs.
I don't have a compression tester but can go buy one if that's suggested.
Today I removed the drivers side catalytic converter. I cut it open with a saw and removed all of this stuff (minus the rock lol) from it.
Doing this definitely got rid of the super rumbly WOT. It's much smoother to accelerate now and does feel a bit more powerful. Yet, since I still hear a very slight rumbling that goes in and out then I'm slightly concerned that there's more cat remains stuck inside the muffler.
As for the misfire, the misfire remains! I really would like to solve the misfire issue before I spend another 1k for a new cat and potentially a new muffler.
Something I noticed is that the misfire seems to only exist after the truck has warmed up a bit. No misfire exists for the first 30s-1m of idling on a cold start and definitely no misfire when driving. I also NEVER seen a flashing CEL as other threads have mentioned. Still hoping to get some more direction on this misfire.
I called a machine shop and got a quote for $400 to fix the heads. I was told that it's very common to have exhaust valve recession issues on these heads and if they got a call for a v6 vulcan engine then they'd automatically assume the problem is valve issues before anything else!
I'll post more detailed pictures of my valves but there is definitely some exhaust valve recession going on with my heads.
thats for both? will they do all the valves? good price, if you can I'd check freeze plugs if your coolant looked rusty. good time to do the water pump too.
I believe this was the worst one (picture above^^^) - With the lowest compression and causing the misfire code P0304
Originally Posted by docm
thats for both? will they do all the valves? good price, if you can I'd check freeze plugs if your coolant looked rusty. good time to do the water pump too.
Yes! It's for both! Although, I did have to supply my own Melling V2047 exhaust valves which were about $71 for all 6 so the total was more like $471. I also had to supply my own valve seals which came with the head gasket kit I purchased. The machine shop owner broke it all down for me. The $400 price includes the following:
Clean the heads + sandblast
Bore out the exhaust valve seats
Install new exhaust valve seats
Cut the new valve seats to match angle of new valves
Clean the heads again
Paint the heads
assemble heads with the new valve seals
I don't know if I'm getting the process order correctly but I generally remember the above explanation is what's going to be done.
Before I left the machine shop, I took some pictures for posterity purposes. Attaching them to this post. Also, I found a youtube video that I thought would also be good to post here as it provided me with the best explanation I could find as to why recessed valves cause low compression (or, at least the best explanation that actually got me to understand it) -
Update! Engine is running great now and P0304 cleared! - I added pictures in my previous post of what the heads looked like when I got them back from the machine shop.
One note on uninstall/reinstall. It's really easy to unmount the AC/PS bracket if you remove the belt tensioner which I would recommend since there's a bolt behind the belt tensioner that becomes easy to remove if the tensioner is out of the way. Other than that, it's a tedious job but not that bad once ya get going.
