Misfire at Idle.

[Tuxedo10-SHO]

I am new to this site but admire the in depth feedback everyone receives on their issues, so I wanted to toss my issue out there for some feedback.
I have a 2010 Sho, 75k miles, PP, LMS 91 +4 tune, 3 bar, etc. I loaded a couple of tunes in starting about 8 months ago, ending up with the 91 + 4 tune in about 7 months ago. I live in Cali, so 93 octane isn't readily available out there.

So my issue is this, I only drive the car about 50 miles on average a month since loading the tunes, don't track the car, but do run it at WOT on occasion when driven....so ultimately , I don't run the car hard that often.
About 4 months or 200 miles ago, i noticed a definite miss at idle ( cant see it on the tach, only when my foot is coming off the brake and car is rolling at idle speed. Once the brake is applied, I really don't notice the miss, or once i'm off idle and going to cruise speed or WOT....there doesn't seem to be any lack of power, but very obvious at idle with my foot off the brake).

I've thought maybe it was a broken plug or bad coil pack, so I changed all of the plugs and found them to be dry with good consistent color, so I don't feel its a coil pack.
I've read many threads here and see one that is similar to what i'm experiencing, and it ended up being a collapsed piston ring land, which i could understand, but that seems somewhat extreme based on my tune and how I drive the car.
The other option is a fuel system issue, possibly the injectors ?

I know my way around engines, but i'm old school, so I don't have the tools to diagnose the internals on these newer cars, so i'm speculating and basically stumped to where exactly to look next.

Sorry that i have limited information, but I am open to any feedback to give me some direction.
I have yet to do a compression test, but that would be my next step, but hopefully someone here has something new that i can look at.

thanks all

 

[mrhighcaliber]

I'm betting carbon intake valve deposits, and or the need for a good fuel injector cleaner. Use a bottle of techron black bottle [not the grey](amsoil p.i fuel system cleaner is great as well, so is the redline cleaner), or the BG cleaner. Use the injector cleaner for 2 tanks. Also, borescope the intake to inspect the intake valves if you can. Oil deposits from crankcase oil vapors routed into the intake, harden on the hot valves and can affect idle quality, but otherwise don't really affect driveability (unless they get really large carbon formations). Since the engine is direct injected, you may have to use the CRC intake cleaner or my favorite, amsoil power foam to loosen the hardened carbon on the valves.

Sent from my Nexus 6 using Tapatalk

 

[Tuxedo10-SHO]

Appreciate the info, and i agree the idle quality could be affected overnight by a clogged injector, but I find it doubtful it would change that quickly due to carbon buildup ?
I agree and will add some injector cleaner to the tank, but to be honest, its going to take me 2 months to burn through a couple of tanks of gas.

I failed to mention that last month took the tune back to stock and took it on a 400 mile road trip. Car ran great at all levels, but didn't lose the misfire symptoms ?

 

[brucelinc]

Even though the plugs looked good, I wouldn't rule out a weak or failing COP.

 

[SHOdded]

Since you have changed plugs, you can check the physical condition of the valves with a borescope. They make decent ones nowadays that hook into USB ports (look on Amazon). I have done this on the naturally aspirated 3.5, I am sure others have done it on the SHO and can lend their experience. If there IS carboning, follow mrhighcaliber's advice.

Also consider buying 1 new coil and swapping out 1 by 1 till you identify the miscreant cylinder (hopefully only 1). I assume no codes are setting in the PCM yet?

It is also possible 1 cylinder is simply running hot for some reason, though Ford has devoted a lot of time and effort to avoid such situations.

Fuel injectors are hard to check without removing from the vehicle. I suppose you could have a power balance check done as a proxy test. Also once deposits build up on these injectors it is REALLY hard to get them off, since the injectors work under such high pressures. Best to keep the fuel system in good shape all along.

Clean both MAP sensors and the sensor in the airbox with MAF cleaner while you are at it.

Former: 1995 ATX, 1992 MTX

 

[Tuxedo10-SHO]

Since you have changed plugs, you can check the physical condition of the valves with a borescope. They make decent ones nowadays that hook into USB ports (look on Amazon). I have done this on the naturally aspirated 3.5, I am sure others have done it on the SHO and can lend their experience. If there IS carboning, follow mrhighcaliber's advice.

Also consider buying 1 new coil and swapping out 1 by 1 till you identify the miscreant cylinder (hopefully only 1). I assume no codes are setting in the PCM yet?

It is also possible 1 cylinder is simply running hot for some reason, though Ford has devoted a lot of time and effort to avoid such situations.

Fuel injectors are hard to check without removing from the vehicle. I suppose you could have a power balance check done as a proxy test. Also once deposits build up on these injectors it is REALLY hard to get them off, since the injectors work under such high pressures. Best to keep the fuel system in good shape all along.

Clean both MAP sensors and the sensor in the airbox with MAF cleaner while you are at it.

Former: 1995 ATX, 1992 MTX

So help me clarify, I would assume if my valves had an above average of carbon build-up causing misfire, the misfire would be erratic verses a steady miss which is what I am experiencing ?
The misfire is a steady miss that only occurs at idle, and is exactly the same during every run, which could be a bad coil pack, but I haven't gotten any codes thrown, which is what perplexes me ? I would think a steady miss would throw a code. ( I wish i would get a code to help direct me in some direction, but that's where I'm frustrated ).
I like your idea of purchasing one new coil pack and swap out each cylinder under i find the culprit....hopefully its that easy.

I still plan to use some Amsoil as well as Techron, but I feel it is more than that since it came on overnight ?....I guess my worst nightmare which still sits in the back of my head is the collapsed piston ring land...anything other than that is an easy fix in my mind, its just finding it that's frustrating me.

Again , I appreciate all of your feedback, and i will let you know when i nail down the issue.

 

[SHOdded]

Yes your concern is very real, unfortunately. Slowly hearing more about engines with lost compression, I believe on bank 1. So it is worthwhile to do a test if the COP swapping bears no fruit. An old test was to squirt a drop of oil to see if the engine behaved better. Also if the rings are leaky, you will likely get oil fouling on the plugs and threads, if it is bad enough. Maybe the rings are sticking and need something like AutoRX to free them. IDK. Really have not heard of indepth physical engine issue analysis with the SHO. One instance of an actual cracked block with the Flex, but really that's about it.

A steady miss may or may not be not carboning. It all depends on the steady state of the process. Active addition may not be fast enough to make it erratic.

As far as codes, misfire codes, like most others I have seen, have threshold requirements. Has to happen so many times in such an interval of time. Maybe this simply does not meet that requirement.

Former: 1995 ATX, 1992 MTX

 

[brucelinc]

I have had no experience with bad coils on the ecoboost engine but the symptoms described and lack of a CEL sounds exactly like my old Lincoln LS when a coil was beginning to fail.

 

[Lostneye]

I have had no experience with bad coils on the ecoboost engine but the symptoms described and lack of a CEL sounds exactly like my old Lincoln LS when a coil was beginning to fail.

The LS was notorious for bad COPs and they had to get pretty bad to throw a code too. When I had mine it went to the dealer for a e-brake error message(electronic on those cars) which somehow was the dual climate control coolant valve and they changed 5 out of 8 COP while it was there.

 

[Tuxedo10-SHO]

The LS was notorious for bad COPs and they had to get pretty bad to throw a code too. When I had mine it went to the dealer for a e-brake error message(electronic on those cars) which somehow was the dual climate control coolant valve and they changed 5 out of 8 COP while it was there.

Thanks for the feedback, I think purchasing a new COP and start swapping is the easiest and least expensive way to go at this time, which should show immediate results once I find the bad one.
The car still has lots of power on the mid to upper range, so finding out that I have a bad COP on a cylinder only means I will have some more power on tap.

IMO the mis is too steady for it not to be a COP on its last legs, but we shall see ............

thanks all.

 

[6500rpm]

I'd be thinking along the lines of mrhigh cal or the tune. Most ignition issues tend to break down under high load/boost rather than idle.

 

[brucelinc]

I'd be thinking along the lines of mrhigh cal or the tune. Most ignition issues tend to break down under high load/boost rather than idle.

I totally agree with this. Ignition issues usually show up under high load. I only bring up the Lincoln LS V8 coil issue because it was counter to this logic. While a completely different engine, the Lincoln LS V8 would typically exhibit the coil issue at idle or just above idle and surprisingly would pull just fine at WOT until the coils got really bad.

 

[Tuxedo10-SHO]

OK so im back again with more information, but the miss continues.
So this is where I stand to date....replaced all plugs, all of the old ones look good with good color, none of them oily or wet.
I bought a new coil pack and moved it to all cylinders....no difference.
I am finally getting it to throw codes...PO3oo, PO304, PO314...the most critical is the PO304, which points to a misfire on cyl. # 4.

So with all of the electrical, plugs, coil pack, etc replaced, I am now looking at the Injector on cyl. # 4.
Unfortunately I dont have the scopes to check on a bad Injector, but with this information, would you feel thats the culprit, or could their be other issues, such as vacuum leaks or similar ?
Im about ready to take it in for a professional overview, but would still like to diagnos myself if at all possible.

thanks,

 

[SHOdded]

Looks like a faulty injector to me at this point.

Former: 1995 ATX, 1992 MTX

 

[TXPony]

Tuxedo10, have you decided on whether to change out the injector or not yet? I'm very curious to see if this fixes your problem or not. My car has had plenty of its own issues, but luckily they've been tied to coil packs going out on me, usually during a road trip so I have to spend bukoo bucks to get it back on the road. I still feel like my idle is a little rough and low, so I'm wondering if I might be on the same path as you.

 

[Tuxedo10-SHO]

TXPony, I havent pulled the trigger yet on the Injectors.
I will do the work myself, but before I tear the top of the engine apart, Im looking for some more solid information on the probability of it actually being the injector verses something else.
I am also contemplating replacing all of the Injectors once I get into it, but that tends to get expensive.

I will send an update once I decide to do the work, but since I seldom drive the car, Its just sitting for now, unless I have a dire need to drive it.
Plus I live in the deserts of Southern Cali where it hit 122 yesterday, so I'm not in a big hurry to be working in the garage in this heat

 

[Tuxedo10-SHO]

So I was finally able to get my car into a shop for some further diagnoses and the worst case scenario was discovered.
They did a leakdown/compression test and found # 4 piston lands were collapsed which is obviously the reason for the steady misfire....I'm surprised the car is still actually running.
I haven't researched anything yet through Ford, but my vehicle is a 2011 Certified with 76k miles, so what I see in Fords Certified warranty is that , "All internal lubricated engine components", so sounds to me like the issue should be covered ????
I am going to start a claim through their Customer Assistance Center and see where it goes, but this gives me a glimmer of hope.

 

[SHOdded]

Sorry to hear. But yes, this work should be covered, whether it is a repair (unlike) or a remanned short block (more likely).

 

[TXPony]

Damn, this is worrisome indeed. I'm almost scared to have my car tested. My miss is barely noticeable to me, but I do fill like there is power missing, especially if I'm not giving it a decent amount of throttle. Although give her WOT and she scoots quite well. I haven't thrown any codes yet, but suspect a compression leak as well. Mine has just over 137K on it so at this point nothing would surprise me except the bill to rebuild the bottome end.

 

[Tuxedo10-SHO]

TXPony,
Mine started as a very slight miss at idle when releasing my foot from the brake, then went away at all levels of the power band with fairly good power.
As time went on ( keeping in mind I put very few miles on the car ) the idle became worse, and the miss became obvious and power dropped even up through the powerband, this is when it started throwing misfire codes.
I'm about 6 months inside the 7 year warranty, so we will see how thing progress with Ford....I will be thrilled beyond belief if the repair is covered.

One question though.....does the PCM have the ability to show that a tune was used on this vehicle at anytime in its life, or is it totally erased when it is returned to the stock tune. I'm just looking at things that the dealer could use to push back and not honor the warranty ?