Cylinder #1 misfire (P0301) and CEL, but only at 4500/5000 rpm and above

[SoCalLuke]

New here, and of course need some help. My searches haven't popped up with the same scenario. So I thought I'd ask the experts here:

Have 2012 RAM Power Wagon with 5.7 Hemi in it, with 92k miles and have owned it since 8k miles.

Late Dec. While towing, I had a blow out (going up hill) on one of the 4 trailler tires and dragging the blown tire cause an increased load on the engine, and the RPM went sky high until I was able to pull over, less than a mile. (I was in Tow/Haul mode.)

As this was happening the check engine light came on, was flashing, and began beeping. The radio, was on, but I also think the engine died when I came to a stop, (but not 100% sure.)

Changed the trailer tire, popped the hood. Oil level was fine and all temps (coolant, oil, transmission) were all fine. So I limped along without straining the engine and checked the code at the next AutoZone. It was P0301.

Ended up finishing the trip and as long as I kep the rpm under 4500 rpm the truck drove fine. Even wheeled it a bit. Then drove home. It was only when downshifting or going up an incline, and going over 4500 rpm which would cause the CEL to flash and beep. Then once the rpm's dropped the light would go solid.

Got home (whether with a trailer or not, whenever I hit 4500rpm would cause the CEL to flash.) Mechanic verified the same code P0301 and replaced all spark plugs, coils, and air cleaner. No CEL light and it ran fine.

One week later, I was playing around with the tow haul mode, while driving on the freeway to see where it shifted. (I just moved from 34x11.5 tires to 35x12.5 and was curious.) Well this spirited driving in tow/haul mode caused the CEL to flash and beep. Slowed down, took it out of tow haul mode and then the light went solid. Kept the rpms down and it drives fine. Mechanic checked and the code was again P0301 and U1449. It was Friday afternoon, he looked at a few things but didn't take anything apart. And reset things.

Today I put it on the floor and watched the rpm climb, when it hit 5000rpm, sure enough the CEL began beeping and flashing. Drove normally, it went solid. Stopped and it went out didn't come back on.

Any guidance? or Suggestions?

 

[HammerHead]

I've been on this forum for years and most misfires are associated with Cam and/or lifter failures. One thing that stands out about your situation is that it's associated with RPM's. Never seen that before.
What oil and oil weight you run? Oil change interval?

 

[Burla]

Sad but true, you are right in the window of cam/lifters, also curious on oil.

 

[Tach_tech]

The first thing to do with a misfire is to start swapping components with other cylinders that aren’t misfiring. Swap the plugs/coil with another cylinder, clear the codes. If the misfire moves to one of the cylinders that you swapped the plugs or coil to then obviously that’s the problem.

If it didn’t move then swap an injector. If it still is on #1 then it’s likely a mechanical issue, start with a compression and leak down test.

I wouldn’t go down the cam/lifter route without doing some preliminary diag first, it’s definitely a possibility though.

 

[SoCalLuke]

I've been on this forum for years and most misfires are associated with Cam and/or lifter failures. One thing that stands out about your situation is that it's associated with RPM's. Never seen that before.
What oil and oil weight you run? Oil change interval?

Oil is factory recommended. Will check paperwork history when I get home to see what actually has gone in.

Going down the compression test, vacuum test. Along with measuring the voltage at the injector. Diagnostics as we speak.

Step 2, Based what they find.
I’ll then swap injectors between 1 and 2 and take it for quick rip and see if it throws any codes.

With no load and low rpm’s engine runs fine.




Sent from my iPhone using Tapatalk

 

[SoCalLuke]

UPDATE: Oil has been synthetic mobil 5W20

Mechanic performed vacuum test and all was normal at various rpms. Checked fuel injector voltage and it was right in the middle. They then drove the truck around with the code reader/scanner connected and noticed the U1449 would come on first, then the P0301. Perusing their technical service bulletin they found, they found TSB 18-049-17 from May 16, 2017. Which says the PCM needs to be reprogrammed.

Going to the Dealer on Friday for two recall items. If they re-program the PCM and it works, I'll scan in my print out about it. For others to see.

Thanks guys.

 

[Burla]

software update, best outcome.

 

[Tach_tech]

Did they read the TSB? The only misfire correction in that flash is P0300-multiple cylinder misfire for vehicles using a block heater in temperatures past -20C.

It’s worth a shot but I’ve never seen a PCM update fix a cylinder specific misfire that can be duplicated pretty easily.

As well after a PCM update has been performed it will take awhile for the misfire monitor to relearn. So you could have misfires but the CEL will not set due to misfire monitor not running.

 

[Hexxus]

bad o2 sensor can cause misfire. Also, I broke the coil on plug boot and didn't replace them immediately, also causes a misfire.

 

[SoCalLuke]

Good to know. Thanks guys.

 

[SoCalLuke]

Dealer wanted to diagnose before reprogramming.....Compression test was good. Now they want to do a leak down test. But I thought that was only good to ID where it is leaking compression, if compression tested bad?

I guess the only way to test the fuel injector is to replace it or swap it with Cylinder #2 and see if the misfire changes to cylinder #2. Or is there a better way?

 

[Tach_tech]

You can still have good compression but have leak down. The leak down test will find that.

 

[SoCalLuke]

You can still have good compression but have leak down. The leak down test will find that.

Thank you. What kinds of problems, with good compression would a leak down test identify?


Thus far:
New spark plugs, new coils
Vacumn test is good
Voltages at the fuel injector are good
Compression test is good

And this misfire code is only thrown when the engine is under load (towing) or flooring it, to make sure the engine hits 5000 rpm. After the CEL goes solid or after the dtc's are reset it drives fine, 100% normal around time, if I keep it under 4000 rpm.

 

[Tach_tech]

A leak down test will tell you if you have a valve seal problem or ring issue. It basically helps to find similar issues a compression test would but is another step if compression is still within spec.

For example the 3.6 engines have had issues with valves not sealing which cause excessive leak down which leads to a misfire but yet they still have good compression.

 

[Musky Mike]

Seems like with all the cam/lifter problems it would be quicker to pull the valve cover and check the lift at the rocker arm of the misfire cylinder. Rule out the cam/lifter first, then mess with coils, spark plugs, injectors and compression if the lift at rocker arm is in spec.

 

[smithwessn]

Do these trucks have variable length intake manifolds? That could explain why the issue is rpm specific and on just a single cylinder. The VVT may be worth checking too, though it would strike me as odd that it would only throw a P0301 code, and not one for other cylinders or the the oil control valve.

 

[SoCalLuke]

Thanks guys. Was at the dealer for two safety recalls and got a free rental 1500, so I figured why not let them do the diagnostics. But now that they want $380 to do a leak down test (after being charged $180 to basically check codes and look things over)....I'm starting to think I should just get it somewhere I trust and pull the valve cover to see what we are looking at.

 

[Tach_tech]

Holy ****. That’s a little pricey for a leak down, that they’re likely only going to do on the one cylinder. That’s gotta be 2-3hrs labour.

We would have done 1hr labour for initial diag which would have been check codes, see it’s a misfire, swap plugs,coil, injector.

Then maybe 0.5hr to do a leak down on the one cylinder.

I wonder what their door rate is.

 

[SoCalLuke]

Yep @Tach_tech , that is crazy high. They checked codes, checked the coil, and did compression test for $180. I asked how long the leak down would take and they said 2 hours. So I said really, so you labor rate is $190 an hour and the service advisor said yes. Guess that is why the dealer ship has service vehicle's filling up 2/3 of their "sales lot," all of the overflow lot and a 2nd overflow lot a couple of blocks away.

Thus, I picked it up on Monday and took it to a place I trust. Today the pulled the valve cover....and called me to come take a look at it. Yep a valve on cylinder #1 was moving less than the others, damn it :-(

I do appreciate you comments and input throughout this forum!


-> I'm in outside sales and camp alot, so the Truck does idle a fair amount more than normal, say while I'm waiting for an appointment or something and I want to run the A/C, while I'm on the laptop or if while out camping to charge up the battery, connected to an ARB fridge.

-> I'll see what parts, they recommend replacing based on what they find, but in your experience what parts would you suggest I replace while it is apart?

I daily drive the truck and tow a 20ft toyhauler with 3-5 dirt bikes in it maybe 10 times a year and every trip involves going up a pass or two.

 

[Tach_tech]

Standard procedure is to replace the cam and all the lifters. Get the heads checked out for any warping as well as valve sealing. That’s what we do in my dealer shop. Shouldn’t really need to do anything other than that.