Slight miss/rpms up down on idle?

[wxman13]

Anyone know if this hose would cause a slight hesitation , rpms are up and down on idle? First off what is the function of this hose? Its very brittle flaking apart. I have a 2005 Winnebago Minnie E450 V10. Thanks for any help.

[wxman13]

40K miles on the odometer

[al1florida]

Where do the hoses go to/from?

I usually trace out the hose to see where it goes to. If it goes to something I am not sure about then I trace what attaches to the something to its eventual source.

[Morich]

Just pretty close to a random guess as I do not know the hoses well enough but the wires attached seem to indicate a solenoid of some type which leads me to guess that it is part of the heating air and not likely to involve the ignition.
But if that item looks that ragged, I would certainly be looking at the plug wires as a logical item to fail and certainly does change the spark question.

[Eagle5]

Hi Wxman13,
That might be a hose for the air conditioning.
I would guess that the idle surge could be caused by a vacuum leak. If you can trace-out the PCV (Positive Crankcase Ventilation) hoses, they must fit well and not leak air. Air leaking into the engine will cause idle surge, and loss of power. Get the doghouse off, and look at everything.
You can probably get a free code-reading at your local auto parts store.
These engines use a coil on plug ignition.
This is the last year of the self-ejecting spark plugs. Because the head only has 4½ threads to engage the spark plugs, if that problem is cropping-up, it is time to get a re-manufactured long block.
Good luck; Eagle5

[wxman13]

Thanks for the responses, the hose I am referring to above goes from the intake manifold to the evap purge valve (the canister looking thing in the upper left corner of the photo, with green cap on it) I replaced the hose with one cut from the same size fuel line but didn't make any difference in the running of the engine. There are no codes being thrown (no check engine light) and its not really that bad, I can just notice a slight skip/miss especially during idle and accelerating from slow speed on the highway. Going to check the other hose (bottom) coming from the purge valve to the charcoal canister for leaks or possible blockage next chance I get. I also can hear air coming from the purge valve itself at times, so it might just be a bad purge valve, but looks like that would throw a code?

[trower]

If you disconnect the wire and start the engine you will get a code. Check the code and it will lead you to what the valve is.

[Rick 99037]

There are sooo many variables to your question and potential answer. But I will go for what I think most likely. At 40,000 miles, your 2005 has had modest use. Certainly engine wear is low, but sitting vehicles have their own list of potential problems.
Gas gets old, and unleaded gas seems worse. They recommend adding fuel stabilizers, and keep the gas tanks full; to help with fuel problems in general. I wonder how old your gas is, and wonder if your fuel system might have gotten a little cruded up from sitting. I'd add a good fuel additive cleaner to my next couple fill ups, and get it out there and run it through a couple of tanks of that, to see if it smooths out. If it doesn't, I'd still suspect things are a little gummed up on the fuel injection side of things.

[DryCreek]

With the purge evaporator line leaking, you should get a code for bank 1, sensor 1 lean or detector stuck lean.

Come to think of it, that line looks like it's on the drivers side - in that case it would be the opposite of what I've seen on an F-53, so look for a Bank 2 Sensor 1 lean/stuck code.

[wxman13]

I've added fuel stabilizer a couple times this past year , and it gets driven at least once every couple weeks, just to keep things moving. Come across a couple of things doing some more checking, the line coming from the evap purge valve going to the evap cannister (I believe), under the motor home, has a section that is being pinched somewhat, which may be restricting flow enough to cause a issue? (Attached a pic). Looks like it was moved previously and not re-attached to its normal location, there is a clip just hanging on the hose and not anchored to anything. Also using my scan tool and mode 6 data, I am seeing misfires on 3 cylinders, #3,#4 and #7, under 20 on #3 and #4, but around 300 on #7 . So might need to replace the coils. But there are no codes (check engine light is off)

[wxman13]

After my last ride, my OBDII scan tool now shows a pending DTC of P0300 (Random Cylinder Misfires) , since its affecting about 4 cylinders, it must be something like a evap blockage or vacuum leak, cylinder #7 shows the most misfires of all of them, so I took the COP off #6 and placed it on #7, but still get the most misfires on #7, #6 stayed at 0 with the COP that was on #7, so that should rule out the COP from #7. The other cylinders that show misfires are usually under 20 or so. If anyone is familiar with the evap/charcoal canister underneath the motorhome, I would like to know if any of you have noticed how the hoses are attached to the canister, If you look at my previous post where I circled where one of my hoses is pinched underneath the canister, I need to figure out how its suppose to be connected, it appears the previous owner may have had something done to that canister and it was not mounted back properly. I've looked but have not been able to find and diagrams showing how those hoses are supposed to be mounted.
Thanks for you help

[Wyatt]

Originally Posted by Rick 99037

There are sooo many variables to your question and potential answer. But I will go for what I think most likely. At 40,000 miles, your 2005 has had modest use. Certainly engine wear is low, but sitting vehicles have their own list of potential problems.
Gas gets old, and unleaded gas seems worse. They recommend adding fuel stabilizers, and keep the gas tanks full; to help with fuel problems in general. I wonder how old your gas is, and wonder if your fuel system might have gotten a little cruded up from sitting. I'd add a good fuel additive cleaner to my next couple fill ups, and get it out there and run it through a couple of tanks of that, to see if it smooths out. If it doesn't, I'd still suspect things are a little gummed up on the fuel injection side of things.

Whether this is the answer to your problem or not, it’s a good post to pay attention to.

[Wyatt]

Originally Posted by wxman13

After my last ride, my OBDII scan tool now shows a pending DTC of P0300 (Random Cylinder Misfires) , since its affecting about 4 cylinders, it must be something like a evap blockage or vacuum leak, cylinder #7 shows the most misfires of all of them, so I took the COP off #6 and placed it on #7, but still get the most misfires on #7, #6 stayed at 0 with the COP that was on #7, so that should rule out the COP from #7. The other cylinders that show misfires are usually under 20 or so. If anyone is familiar with the evap/charcoal canister underneath the motorhome, I would like to know if any of you have noticed how the hoses are attached to the canister, If you look at my previous post where I circled where one of my hoses is pinched underneath the canister, I need to figure out how its suppose to be connected, it appears the previous owner may have had something done to that canister and it was not mounted back properly. I've looked but have not been able to find and diagrams showing how those hoses are supposed to be mounted.
Thanks for you help

Ok sorry, which engine do you have? I’m not ruling out a bad valve seat on #7.

[Eagle5]

Hi Wxman13,
As Wyatt mentions about about a bad valve seat, does your engine crank smoothly when starting, or does it surge? A surge during crank indicates that one cylinder has lost full compression.
Because the problem does not move with the Coil-over-plug, perhaps Spark Plug #7 is bad?
Eagle5

[Wyatt]

Originally Posted by Eagle5

Hi Wxman13,
As Wyatt mentions about about a bad valve seat, does your engine crank smoothly when starting, or does it surge? A surge during crank indicates that one cylinder has lost full compression.
Because the problem does not move with the Coil-over-plug, perhaps Spark Plug #7 is bad?
Eagle5

I agree that number seven seems to be problematic. But I thought he switched out number six for number seven so perhaps I miss read that.

But that’s definitely a good place to look I thought that was already done.

The valve seat might not have lost all compression but just enough to make it run rough. This is happened on more than one vehicle I worked on where the valve burned just enough to lose some compression, and mix the incoming fuel with the compression and exhaust cycles.

That’s why I asked what type of engine he has I would like to know where in line number seven is in the bank. And firing order.

[Eagle5]

Hi Wyatt,
This is a 2005 V-10; the last year with only 4½ threads to engage the spark plugs. The coils were switched between #6 & #7, but not the spark plugs. Number 7 is second from front on the driver's side.
Eagle5

[wxman13]

Yes it is a V10 6.8L, has 40K miles, it starts just fine, no noticeable misses during initial start, the misses are after warmup, esp at warm idle, and also noticeable when accelerating on the highway. I would as stated earlier like to get the hose on the charcoal canister routed correctly so its not being pinched the way its run underneath the canister, but haven't been able to find a diagram or look at a similar motor home setup.
Also I don't let it sit more than 2 weeks without at least driving it, at least 20 miles or so.
And I use fuel cleaner every so often, and on the last trip I put 2 containers of Berrymans B12 in the tank, before adding some extra fuel to the tank. I run the generator every so often as well, it seems to run just fine.
And yes I need to remove the #7 spark plug, and inspect it, and maybe the injector on #7. But even if the hose on the charcoal/evap canister is not the cause of this issue I need to get it re-routed so its not being pinched.

[Wyatt]

Originally Posted by Eagle5

Hi Wyatt,
This is a 2005 V-10; the last year with only 4½ threads to engage the spark plugs. The coils were switched between #6 & #7, but not the spark plugs. Number 7 is second from front on the driver's side.
Eagle5

Well, I agree then, it could be as only as a spark plug. The reason I asked about which cylinder is because the ones in the middle tend to have more problems with the valves than the ones on the outside due to the extra heat.

Not trying to be an alarmist it might be as simple as what the OP is considering but, hey, we’re all just weighing in here to add more thoughts.

[wxman13]

Well, #7 spark plug seems to be the issue, notice the carbon trace from the top to the base, there is one on both sides of the plug, new plug installed no misses so far, still need to fix the charcoal canister hose, if I can find out the correct routing of the hose.

[Eagle5]

Hi Wxman13,
Glad you have it fixed!
Eagle5