2013 F-150 5.0 running rough

[patperry2766]

2013 F-150 5.0L 2WD

Got a CEL and took it to parts store and their OBDII reader said cyl # 7 misfire. Truck seemed to run fine and it went away pretty quickly, so I just disregarded it.

About 3 weeks later another CEL light came on, but again it was dx'ed as cyl #7 misfire, went away pretty quickly, but I replaced the plugs anyway because of the mileage. Motorcraft factory replacements gapped to .51.

I went ahead and replaced the coil anyway about a week later and noticed my gas mileage starting to go down, about 1 1/2-2 MPG. Checked the air filter seemed to be fine with no excessive dirt build-up so I just blew it out with the compressor.

I had a brain fart and took throttle body off and cleaned it thinking it was the MAS. In my defense, it looked strikingly similar to the MAS on my wife's Escape that I've had to replace a couple of times. I didn't replace the gasket because I didn't have one.

I can't remember exactly when it appeared but the engine seemed to be running rough when in P or N, but if I have it in D with my foot on the brake, I can't sense it running rough, nor can I detect it running rough when driving.

Today, I gapped the plugs down to .49 and cleaned the real MAS, but still feel the rough idle. Should I replace the throttle body gasket to make sure I don't have a air leak? MPG is still down abnout 1 1/2-2 MPG.

I really don't want to have to take it to the dealership, any thoughts on what else I need to check?

I've considered pulling the old coil back on just to make sure I possibly didn't get a defective coil. All replacement parts have been factory Motorcraft replacements.

Any help or suggestions will be greatly appreciated

[carringb]

You simply a power imbalance the most at high-load / low rpm.

When you take it somewhere else, let the know you already had a relative compression test done, and want a manual compression test on #7 (the #4 is probably just an artifact caused by #7). And also a leak down test, which will show which valve is leaky of that's the case. While they're in there, they should stick a borescope in that cylinder, and see if there's any crud hanging onto that valve causing it not to seat fully. It might just need a machined-dosed carbon cleaning!

[patperry2766]

Yes,
They only did a relative compression test. Tech was already gone and the service advisor said. "well, there is another compression test that we could have done, but it would have cost money"...Duh. That's why I brought the truck in.

Per the notes on the receipt: "EEC tested and found DTC P0316 random misfire detected. Performed power balance and found dead misfire con cyl 7 and cyl 4 also dropping at times. Removed and inspected spark plugs-found no concerns. Performed coil stress test-found coils passed. Checked power and ground circuits and coil & injector using noid light-found pass.

Checked relative compression and found cyl 7 8% low. Pinpointed internal engine fault, suspect valve not seating causing compression loss. Due to mileage, recommend long block"

There are several things that just don't make sense to me:

Why will it idle fine in gear, but when in P or D is when the rough idle is most pronounced?

Can't detect a miss when driving but MPG's are down.

Guess I'm gonna have to find another place to do a proper test.

What do I need to be telling them needs to be done so I can stop wasting time taking it place to place getting incomplete diagnosis?

[carringb]

That's a good point. If they only gave you a percent low, they really just did a cylinder contribution test, and not an actual compression test. There could still be carbon buildup on the valve causing that variation.

[turbojimmy]

mich800 wrote:

patperry2766 wrote:
UUGGHHH...

The dark negative thoughts in the back of your mind that you repress, hoping they don't come true.....came true.

Took truck into the dealership. Have a misfire on #4 & #7 with 8% low compression on cyl #7. They are recommending replacing the motor to a tune of almost $11K. That ain't gonna happen.

So...
#1 go to independent and have them replace with crate engine or one from a junk yard and just keep chugging along hoping that the problem won't reappear again in 125K miles

#2, take to independent and have them do a valve job, hoping that's the only source of the low compression and it will solve the issue. If anyone knows a reputable mechanic in the Ft Worth Texas area, I'm all ears.

#3 trade it off

I don't really see a good way of getting out from under this problem best case for under about 5K, the truck is paid off. Should I take whatever equity I have, plus the money to fix the repairs and get something new? The local Ram dealership has some smoking hot deals on the remaining '18's 2500's & 3500's

Fire away

An 8% variation on cyl 7? Without further diagnosis I am not sure that is enough to through the engine out yet.

Yeah an 8% variation isn't enough to worry about. 10% is a good rule of thumb but I've seen worse variations in good running engines.

My money is still on fuel delivery. Just sayin...

[mich800]

patperry2766 wrote:
UUGGHHH...

The dark negative thoughts in the back of your mind that you repress, hoping they don't come true.....came true.

Took truck into the dealership. Have a misfire on #4 & #7 with 8% low compression on cyl #7. They are recommending replacing the motor to a tune of almost $11K. That ain't gonna happen.

So...
#1 go to independent and have them replace with crate engine or one from a junk yard and just keep chugging along hoping that the problem won't reappear again in 125K miles

#2, take to independent and have them do a valve job, hoping that's the only source of the low compression and it will solve the issue. If anyone knows a reputable mechanic in the Ft Worth Texas area, I'm all ears.

#3 trade it off

I don't really see a good way of getting out from under this problem best case for under about 5K, the truck is paid off. Should I take whatever equity I have, plus the money to fix the repairs and get something new? The local Ram dealership has some smoking hot deals on the remaining '18's 2500's & 3500's

Fire away

An 8% variation on cyl 7? Without further diagnosis I am not sure that is enough to through the engine out yet.

[carringb]

So... Why did #7 lost compression? They should have done a leak down test to make sure it's a valve issue and not a ring issue.

If it is a valve issue, I'd go ahead and just drop on a reman'd head. Or have the head rebuilt local. But you'd want to change injectors at the same time, because a bad injector is about the only way to burn up a valve or valve seat.

If it's rings, I think a reman motor is the way to go. The Ford complete remans are a pretty good deal for what you get. Just don't do it at a dealer. They charge to much. The Ford remans have a 3-year unlimited mile warranty, and warranty work can be done at any Ford dealer even if a Ford dealer didn't install it.

[patperry2766]

UUGGHHH...

The dark negative thoughts in the back of your mind that you repress, hoping they don't come true.....came true.

Took truck into the dealership. Have a misfire on #4 & #7 with 8% low compression on cyl #7. They are recommending replacing the motor to a tune of almost $11K. That ain't gonna happen.

So...
#1 go to independent and have them replace with crate engine or one from a junk yard and just keep chugging along hoping that the problem won't reappear again in 125K miles

#2, take to independent and have them do a valve job, hoping that's the only source of the low compression and it will solve the issue. If anyone knows a reputable mechanic in the Ft Worth Texas area, I'm all ears.

#3 trade it off

I don't really see a good way of getting out from under this problem best case for under about 5K, the truck is paid off. Should I take whatever equity I have, plus the money to fix the repairs and get something new? The local Ram dealership has some smoking hot deals on the remaining '18's 2500's & 3500's

Fire away

[Grit_dog]

Slight vacuum or intake manifold leak somewhere?

[patperry2766]

boogie_4wheel wrote:
Start easy, swap #5 and #7 coils; regardless of the new coil let's prove the new one.
Was there any build up on the plug that you removed? Evidence of oil consumption?
Is this a cold misfire only?

Misfire when not under load has me wanting to think oil ingestion (stem seal), or weak compression. If the injectors are halfway easy to get to, swap their location as well to see if the problem follows the injector.

The original plugs with about 120K miles on them looked great, no evidence of oil consumption or any other indications of internal problems.

[patperry2766]

Gonna try replacing the PVC valve, if it doesn't help then I'll consider it part of the PM I need to do. I do have a recall for the transmission, I guess if I can't get the problem resolved. I'll just have them check it out when I take it in.

I'm not a big advocate of just throwing money at a problem hoping it will fix it.

[patperry2766]

jerem0621 wrote:
What brand coil did you use?

I used Accell coils on my V10 and had no positive results.

Go OEM on the coils if you can afford it. When I start chasing misses I change the boots and springs and if that doesn’t work I replace the coils. It can be maddening to find the right coil that is missing.

I did use aftermarket coils on my V10 from a company called Uneek Supply and the coils performed great.

Also, and JMHO... I I put dialectic grease on the connections and I normally replace ALL of the boots and springs on my coils when I change the plugs on my Ford products.

As for plug gaps I just set them per the owners manual.

Also, the fuel filter may need changed. People don’t change them anymore it seems.

Thanks!

Jeremiah

Used Motorcraft plugs & coil. Fuel filter is in the tank and built into the fuel pump from all the research I've been able to do.

[boogie_4wheel]

Start easy, swap #5 and #7 coils; regardless of the new coil let's prove the new one.
Was there any build up on the plug that you removed? Evidence of oil consumption?
Is this a cold misfire only?

Misfire when not under load has me wanting to think oil ingestion (stem seal), or weak compression. If the injectors are halfway easy to get to, swap their location as well to see if the problem follows the injector.

[mich800]

In the absence of a hard code, live data/data logging will probably be the best way to diagnose an issue. You are probably just chasing your tail without any objective data on what is going on or where to start.

[carringb]

patperry2766 wrote:
125K, The CEL wasn't on when I replaced the coil, it had been off for about 2 weeks. I figure that was enough restart cycles to clear anything in the system. Hasn't thrown a CEL since I replaced coil about 2 weeks ago.

I keep vehicles till the wheels fall off so I'm usually pretty good about taking care of stuff.

I'm with Jerimiah above... Make sure you use a Motorcraft coil. Equivalent is fine (Napa Echilon, Denso, etc). Most parts store grade coils are not equivalent.

125K is long time to run the OEM plugs is that was the 1st changeout. Doing this can damage coils, which can cause other cylinders to run weak besides the one you changed. The best way to continue with diagnosis (assuming other PM work is up to date, like fuel filter and PCV valve) is to run a cylinder contribution test. Which requires a diagnostics terminal or laptop connection.

[Lynnmor]

A good place to start is a compression check. You need to know if the engine is healthy before throwing a lot of parts at it.