2005 Ram 4.7L major misfire but Goodyear's computer says no problem

Maintenance/Repairs
1

About 2 weeks ago, my 2005 Dodge Ram 1500 4x4 was running fine. The very next morning, it’s 4.7l engine has a very obvious misfire situation where it’s hesitating badly, especially under acceleration at lower rpms, with the shaking feeling in the steering wheel etc etc. I have Advanced Auto parts and 2 separate auto shops plug in their little boxes to find the problem codes. The check engine light came on and stayed on as soon as this issue began. The codes they got were consistent from place to place: 1. Misfire on cylinders 4 & 6, and 2. Random multiple misfire.

So I go and buy 2 brand new coils for cylinder 4 and 6, and 8 new champion plugs. I was in Florida for a week, so the truck was NOT driven at all after the day this problem began. So I replace all 8 plugs and install the 2 new coils, but it makes NO DIFFERENCE. It’s still hesitating just like before. Today I take it to Goodyear to have them do an allegedly thorough evaluation. They use their little code box and they get the same codes as mentioned above about random multiple misfire and misfire on cup 4 and 6.

Then the mechanic takes the truck for a ride and experiences the same hesitation and shaking under acceleration. So he replaces both of the new coils I had installed with their coils and replaced the 2 new plugs, just to make sure there was no issue with these new parts. He takes it out and apparently plugs in a different computer that monitors all engine functions, including air/fuel mixture, spark etc. According to that computer, the truck is running properly(according to them), and he checks compression and says it’s good. So they have no idea what’s wrong, and he said that my car’s computer was reset so the check engine is no longer on(I am not clear the how’s and whys of that part). But the important thing is that it’s still running badly and they can’t tell me why it’s running badly!

The mechanic said maybe a lifter collapsed or there is sludge that’s causing an issue, but no solid explanation. Supposedly the 4.7L Dodge engine has a sludge issue experienced by some owners, and the mechanic recommended replacing the oil every 1500 miles instead of 3000.By the way, I asked how much it would cost for Goodyear to check the lifters and check under the valve cover, but he said they don’t do that.

Ok. This leaves me $200 short after buying the parts 2 days ago and then paying Goodyear to evaluate it, but I am no closer to an answer. If you have any questions let me know and I’ll answer them if it helps. Thanks in advance…

2

They don’t do that because Goodyear doesn’t employ any mechanics, A misfire code doesn’t identify the cause of the misfire. For example you could have swapped the plugs and coils from a cylinder that was not misfiring to one that was and seen if that caused the codes to also change cylinders.
There are better ways to diagnose it but it would require equipment and expertise that you don’t have.

Find a good local shop and have a real mechanic take a look at it.

I don’t fault you for trying to save money by replacing the plugs and coils yourself but going to tire shops or muffler shops is best for when you need a tire or exhaust work. I personally stay away form all national chains for car repairs.

3

You replaced the coils and plugs but not the wires? Or doesn’t it have wires? Wire would have been the first thing I would have replaced. With GM anyway, the dealer has the best scan equipment that the local Goodyear does not.

4

The computer defines misfire as failing to detect the crankshaft accelerate when it should, after the spark plug fires. So it is saying the crank position sensor isn’t seeing the crankshaft accelerate after each of those spark plug fires their respective cylinders.

So think about what you need inside a cylinder for a proper firing

  • fuel and air at the correct mixture
  • compression
  • good, healthy spark
  • at the correct time
  • exhaust gasses freely flowing out of cylinder

Since you are getting a random misfire code, forget about cylinder 2,4, and 6. You’ve got misfires on all cylinders. So it must be something that is affecting all cylinders. Here’s some ideas of things that could fail that would cause that to happen, listed in order of my guesses for likelihood

  • Bad fuel, for example water in the fuel
  • Ignition module
  • Fuel rail pressure
  • Crank position sensor
  • Cam position sensor
  • Engine coolant temp sensor
  • Engine air filter
  • Engine fuel filter
  • MAF or MAP sensor
  • Wires, coils, spark plugs (entire HV ignition system wiring)
  • O2 sensors
  • Cat
  • Valve timing
  • Leaking valves or pistons
  • Engine computer

So what to do? One idea, consider taking it to a dealership or an independent shop which specializes in this make. They’ll have the proper tools and experience to make a diagnosis.

Don’t want to do that? hmm … well, then I’d start off with a look see at all the fluid levels, the battery system voltage levels, then the affected connectors per the list above, then check all the fuses affecting the list above, then a compression check probably. After that, especially if that happened soon after refilling the gas tank, checking for signs of fuel contamination, water, etc. Then a fuel pressure test. Then an intake manifold vacuum test.

5

This truck is 11 years old

Plenty old enough for injector pigtails and coil pigtails to be brittle, causing misfires

I’ve seen this on plenty of vehicles of this vintage

Nothing mopar specific about that

Rotten wiring has thrown many guys for a loop

6

If a lifter was collapsed you would know it as it would be rattling. You state a misfire on 2, 4, and 6. Later you state misfire on 4 and 6. Does this mean 2 is fine now?

While not 100% definitive you might consider checking the injector pulse with a stethoscope to see if there is a rhythmic click on the iffy cylinders. That could go along with what db4690 mentioned about injector pigtail problems.

You might also consider having another shop look at it. While I won’t lump places like Goodyear and Firestone all together I personally consider these chain operations to be a bit shallow on some things so to speak.
The pay system isn’t good enough to cause them to be proficient or to care.

7

“The pay system isn’t good enough to cause them to be proficient or to care.”

That’s because they don’t employ real mechanics in their shops.

8

There is no misfire on cyl 2 listed in the codes. I was listing the 2 codes by saying 1. A misfire on cylinders 4 and 6, and 2.(2nd problem) random multiple misfire. Maybe I shouldn’t have listed the two problems with a 1. And 2. Ahead of them.

9

Part of the problem here is that I have rarely ever needed to take my vehicles to the mechanic because I can usually find and fix the problem myself. However, many of the cars I’ve owned were models from 1965 to 1970’s. I have always liked the simplicity of older cars, and been leery of the complexity of newer cars, and this ordeal is reinforcing that notion… It seems to me that early models were often made to be user friendly from a maintenance standpoint, while newer cars seem to often be designed to be “wallet-friendly” for mechanics. Also, I bought this truck new and haven’t had any confusing issues like this. One poster had a good point when he mentioned replacing plug wires, but i am trying to avoid the problem of having to replace a whole bunch of separate parts, only to find that I still haven’t found the problem yet, AND my next door neighbor just had this same exact issue with his 2002 Buick Park avenue Ultra’s 3.8l engine, and it turned out to be one of the 3 coil packs, which influenced my decision to spend $48 on 2 new coils and $20 on new spark plugs, which were overdue anyway.

But obviously the list of possibilities has greatly increased since earlier, according to a list from a poster above^^. I made the mistake of assuming that Goodyear was capable of figuring out this problem, and I chose them because they work on my mother’s car and more importantly, they are only 1/4 of a mile away from where I was working today, and I had to drop it off and walk to work. I guess you could say that “convenience” was what doomed me earlier today…

10

I had a lot of coil on plug issues with a '04 Ford T’bird. This was a common issue with T’birds and the COP repair was handled with an extended warranty. On my bird one coil failed at 23K miles then at around 30K another, and a month later another. It was aggravating and eventually Ford just replaced all 8 coils and plugs and said I was on my own from then on. At 72K miles now all has been fine since.

In your case when 1 coil fails the others are just as old and are likely to fail too. You can move coils around from cylinder to cylinder to find the bad coils. But I’d recommend replacing all of them at some point. Often the boots and springs that go between the plug and the coil break down due to age and heat. NAPA sells sets of new boots for many cars and that’s something I plan to do soon on my bird. I suspect the boot goes bad, causes the current to arc and soon kills the COP.

If your motor has variable valves, and you have ruled out COP’s as the problem, it might be a malfunction of the variable valve system. Since this issue seems to be at lower rpm, if the motor smooths out at higher rpm and has normal power at higher rpm (ie 4,000 rpm) that might be a clue of a variable value problem.

It might be time to take this truck to a Dodge dealer. They have more specific diagnostic equipment and this seems to be a more complicated problem.

11

db writes …

Plenty old enough for injector pigtails and coil pigtails to be brittle, causing misfires

Wouldn’t that cause a lean code in addition to a misfire code? I wonder if a real time test for fuel trim would help.get to the bottom if this more quickly.

12

@GeorgeSanJose

Depends on just “how lean” it is . . .

If it’s lean, but hasn’t exceeded the threshold to set a code . . .

If you’re not too smart, and not very experienced, and don’t know what pids to look at on a scanner, for example, you will miss out on a lot of clues. There’s a lot of good information out there. You just have to know how to find it, and where to look

Sadly, we had a few cases where our Ford trucks were still under new truck warranty, and they had hesitation problems. The yahoos over at the dealer didn’t know how to diagnose a darn thing and handed us the truck back, without fixing it. We threw new plugs and boots at it, and the problem was fixed. By the way, these were NOT throwing any kind of codes whatsovever

Another thing . . . according to Ford information, the ignition tune-up wasn’t due. Either by time or mileage. Yet the plugs and boots were bad, and were the sole case of the hesitation problem

We don’t even have a genuine Ford scanner at work, but we figured it out. We sent it out to the dealer, because the truck was under warranty, and we figured “Why bother tying our guy up, if Ford can pick up the truck and fix it under warranty? That’s what warranty is for, right?”

Had we known what imbeciles they were, we would have said “Well, even though it’ll cost us a few bucks to fix the truck, at least we’ll have it done quickly, versus sending it to the dealer, and those guys don’t even know which end is up, anyways”

My point being, if you don’t know what to look for, your chances for figuring it out aren’t very good

13

Not sure if this issue still persists in Mopars these days…However Intake manifold gaskets used to wreak HAVOC on owners…and would often present as Random Misfires. I recall dealing with several of these in my day…and prior to me knowing that this was a common problem…I went about troubleshooting it beginning with the ignition system and soon began looking for other solutions.

Methinks you have faulty intake manifold gaskets… One thing about these intakes…the ones that look like a loaf of bread sort of is that Dodge intentionally cut an ENORMOUS hole in these intakes and installed a gasket and a piece of sheet metal over the gaping hole that is on the under side of the intake manifold… These gaskets fail and or the thin sheet metal warps…allowing huge intake of unmetered air into the engine…causing Lean condition and Random misfires on all cylinders.

There is a company that makes a thicker plate for this as well as a better gasket… If this is the same setup as the 5.9L V8 then its the plate on the bottom of the intake manifold… Look it up on the net to see in detail what I am talking about. Its Old Hat news at this point as all Dodge Ram owners with that manifold have or will deal with this situation. I still dont understand why they cut such a huge square hole in the bottom of that manifold… I saw no reason for it that I could think of…but hey…these things are probably above my pay grade. The ones I have repaired I simply used the factory or Fel Pro gasket AND some Ultra Grey silicone gasket maker. When I remove these belly plates on the manifolds…I find that I can almost remove the ten or so bolts with my fingers they are so loose. The metal plate is indeed thin and aftermarket guys make a thicker one…others make a one piece manifold costing clost to 800 bucks… I found that a new gasket…some Silicone and some thread lock compound do the trick nicely… Never had any issues after I do them… Many are running today…I constantly get referrals from the guys still driving their trucks. Most cannot believe how much better it runs after this service…as it was probably leaking for a long time. These guys think I am some sort of clairvoyant or something… but its just simple mechanics… IF you have this same manifold…your problem begins and ends here. That is of course if its not simple ignition stuff. Easy to rule out quickly tho.

I really HATE to think they used that same manifold after all those problems. The manifold can also leak coolant down into the cylinders as well…reading the plugs can tell you which one is drinking and burning coolant. My guess it this manifold is totally different than the older 5.9’s…at least it better be!

IF your engine shares the same intake manifold as the 5.9 style…this is the very first thing I would address. Do in internet search for leaking intake manifold gaskets on this year and model…bec if they used the same manifold…i promise you…its that plate and gasket leaking. No doubt. Lot of “Ifs” in this writeup so look it upski… I have to do a Timing Belt at the moment

Blackbird

14

There u go

15

Methinks this is NOT the same manifold…however it can leak air at the bottom seal areas…causing lean condition and random misfires. It can even be cracked where the two halves meet. Can also leak coolant into cylinders…but coolant leak wont produce lean condition. Perhaps if they werent made of PLASTIC maybe this crap wouldnt happen so much?

Blackbird

16

I don’t think plastic has anything to do with intake leaks

Ford and GM both use plastic intake manifolds AND those plastic/rubber type of intake gaskets

However, that “rubber” material on the gaskets does go flat over the years

17

The Chrysler 4.7L is an overhead cam engine unrelated to the 3.9, 5.2, 5.9L engines.

As for the opening in the bottom of the old Magnum intake manifolds Dodge didn’t cut them, the manifolds were cast that way. This was a simpler way to make a casting. The replacement Mopar manifold belly pan gaskets are metal and don’t break apart like the originals.

18

To date I have replaced 6 plastic intake manifolds for various leaks…found using a smoke machine and and air compressor.

I agree they usually work ok…but when troubleshooting keeps pointing to unmetered air and misfires and lean conditions… Those manifolds…metal or plastic or Play Dough…get pulled and torture tested… Ive seen 6 thus far fail this test… Buying a new manifold…doing the same test…with no evidence of leakage, then installing…the problem was solved. Each and every time. So while you shouldnt automatically suspect a manifold because it is plastic…they are certainly NOT immune to problems. I dont make this sxxx up…I just have to deal with and repair them.

Blackbird

19

@“Honda Blackbird”

You’re not the only one here who regularly uses his smoke machine. I have my own and use it regularly. It’s nearly indispensable, IMO. Sure, you can sometimes find leaks with cigarette smoke and carb cleaner. But it won’t tell you the size of the leak.

I’m sure you weren’t implying that, by the way

I’m just making my own statement

Have you yet replaced plastic intake manifolds, because the “swirl flap” actuators broke, which in turn caused the manifold to shatter? I did one of those recently

There are still a few guys who think EVERY intake leak that is bad enough to cause a P0171 or P0174 will also cause the engine to visibly run rough, and it will also be an audible leak. I’ve seen enough intake leaks to disprove that theory.

20

Ha…no a real smoke machine thank you very much. I havent seen the swirly flapper thing yet…but Im up for it… Lol

Intake AIR leaks are a difficult one if I do say so meself… I dont know of any other way other than smoke to check the manifolds out honestly… maybe pressure testing with nice accurate gauges or something…but that wont tell you precisely where the leak is. Yeah man…intake leaks are a Royal pain in the neck…and the symptoms…especially when the condition is slow to manifest… Oh Brother… Like it sort of runs perfect…but not really type of stuff…its enough to drive you nuts!

I dont know how I feel about plastic engine parts… Maybe the block with be plastic one day…who knows. Hopefully I will be pushing up Daisys when that happens.

Blackbird