ICE running a little rough at 105k

[reverendalc]

Hey all,

 

years of smooth sailing and MKZ loving are winding down… I’ve got a little over 105k on the clock, and my combustion engine is getting kind of rough.  I’ve watched my MPG slowly dwindle, and I’m down to 41.0 combined when i was steadily around 41.9 in its younger days. Still excellent mileage, but I’ve never tuned up the ignition. 
 

ive tried searching the forum, but it’s yielding lots of junk… I apologize if this has been asked a lot and I just can’t find it, but…

 

what does everybody like for plugs?  Mine are about 60k old. Should I swap the coil packs, and if so, what do we like?

 

I want my MKZ to purr again

[bbf2530]

10 hours ago, reverendalc said:

Hey all,

 

years of smooth sailing and MKZ loving are winding down… I’ve got a little over 105k on the clock, and my combustion engine is getting kind of rough.  I’ve watched my MPG slowly dwindle, and I’m down to 41.0 combined when i was steadily around 41.9 in its younger days. Still excellent mileage, but I’ve never tuned up the ignition. 
 

ive tried searching the forum, but it’s yielding lots of junk… I apologize if this has been asked a lot and I just can’t find it, but…

 

what does everybody like for plugs?  Mine are about 60k old. Should I swap the coil packs, and if so, what do we like?

 

I want my MKZ to purr again

 

Hi rev. Personally, I would recommend sticking with the Motorcraft plugs. You can find the correct spec/part number in the Maintenance and Specifications in your Owners Manual.

 

Whether to change the coil packs or not really depends on personal preference. If they are operating correctly, there would be no great necessity to, at this point. However, the age old question is..."If the engine is running rough, how do we determine if they are working correctly or not"? If changing the plugs does not cure the issue, then you could try switching coil packs around to see if it affects performance. But that can become tedious. So...as long as you are doing the plugs, it would not hurt to replace the coil packs, if you do not mind spending he money.

 

Let us know how you make out and good luck.

[reverendalc]

Thanks for that!  I was on the fence between iridium and motorcraft plugs.  Considering how affordable the coil packs are, I don’t see any harm in replacing them… I guess I’ll stick with OEM there too!

 

i can’t really think of anything else that would cause my ICE to run a little rough, or sometimes “diesel” a little bit on start/stop. 
 

can you?

Edited June 5, 2021 by reverendalc

[Multitask]

quality of gas will do it....

could be time to get the injectors cleaned...

[reverendalc]

Hmm. I tried using premium for a few months but didn’t see any difference, possibly the impact of regular was already done?  I’m not opposed to getting the injectors cleaned though, she’s been good to me and it’s my turn to be good to her!

 

I always buy gas at 76 or chevron or Texaco, but not premium. Is anybody suggesting premium?

[bbf2530]

3 hours ago, reverendalc said:

Hmm. I tried using premium for a few months but didn’t see any difference, possibly the impact of regular was already done?  I’m not opposed to getting the injectors cleaned though, she’s been good to me and it’s my turn to be good to her!

 

I always buy gas at 76 or chevron or Texaco, but not premium. Is anybody suggesting premium?

 

Hi rev. Regular and premium fuels from major name brand gasoline manufacturers contain the same detergents. Using premium will do nothing to clean the engine/injectors or keep the engine any cleaner than regular fuel.

There is no need to use premium fuels, if you are using a quality, name brand fuels (which you are). Or in other words, there was no "impact" from you using regular fuels. Our engines are designed to use octane from 87 to 93, and simply adjust timing for the octane rating (a simple/basic explanation).

 

What premium fuel will do is allow the engine management system to give you the full power rating (hp/torque) advertised for your engine. That will essentially give you ~20-25 more horsepower (probably less in a Hybrid) when using premium over regular.  So unless that small amount of power matters to you, save your money and use "76 or chevron or Texaco" regular.

 

What you can do to clean your injectors is use a quality fuel injector cleaner such as Techron (my personal go to).

 

If your MKZ has a turbocharged engine, do not use engine intake cleaner services which some shops will try to sell you on, as they will cause issues with the turbochargers. In fact, Lincoln/Ford specifically tell us not to use them.

 

However, a fuel injector cleaner like Techron (which you add before filling your tank) are permitted and good to use for periodic maintenance.

 

I am sure others will jump in with more suggestions.

 

Keep us updated and good luck.

Edited June 5, 2021 by bbf2530

[reverendalc]

This isn’t my first hybrid, and I’ve never had problems using regular unleaded. I don’t hypermile, but I do drive consciously of those pretty little leaves on my tree and my combined economy (it’s kind of a game, the only way I stay sane driving all day). 
 

ive never had much luck with OTC “fix in a bottle” products, but i guess it’s worth a try. I’ve got a couple other cars so I thought why not yank the injectors and take them Dr Injector for an ultrasonic bath. 
 

has anybody tried both the bottle and the professional cleaning, that can offer a comparison?

 

thanks all!

[Multitask]

I've been buying from a place that I don't know where they get there gas from, but it's the least expensive around here (will under 4) sometimes I put in the middle grade...

ONe thing I noticed on my journeys, was some places had 88 as the lower one... and some had 'pure' gas... I'm assuming no ethanol at all

I do concur it might not make much difference... I was talking more about the non-brand... maybe having more water in them...  ?

 

I do know that tires make a difference too... while I don't like the ones I got , they are slowly getting better for mileage...

 

[reverendalc]

I never put much stock in the fuel quality because I don’t buy from no-name, unbranded stations. I haven’t tried pure gasoline, but again that’s just a thought. 
 

it’s interesting that you mention tires!  Around the time I noticed my mileage slowly declining, I DID put new tires. I had some excellent summer tires, but the roads are so continuously wet here that I opted for an all-season tire. I would imagine that tires could easily account for a .9mpg decrease in economy. 
 

too bad they can’t be blamed for my ICE /-:

Edited June 6, 2021 by reverendalc

[bbf2530]

6 hours ago, reverendalc said:

This isn’t my first hybrid, and I’ve never had problems using regular unleaded. I don’t hypermile, but I do drive consciously of those pretty little leaves on my tree and my combined economy (it’s kind of a game, the only way I stay sane driving all day). 
 

ive never had much luck with OTC “fix in a bottle” products, but i guess it’s worth a try. I’ve got a couple other cars so I thought why not yank the injectors and take them Dr Injector for an ultrasonic bath. 
 

has anybody tried both the bottle and the professional cleaning, that can offer a comparison?

 

thanks all!

 

Hi rev. there is absolutely no reason you should have problems using regular unleaded, since your MKZ is designed to run on 87-93 octane fuel. As Multitask and I stated, it is the quality of the gas, not octane, that may/will cause issues. Using regular gas (87 octane minimum) will not cause any problems, assuming it is good quality fuel. And since you are using name brand fuels ( 76/Chevron/Texaco), fuel quality is probably not the problem.

 

Just few observations: First...A drop in fuel mileage from 41.9 to 41.0 is very small. Negligible in fact. Changes in the ethanol content in your area, old/worn spark plugs, weather changes, using AC more, and other driving environment changes etc., could/would account for far more than a small drop like that. The reality is, a mileage drop like that is not actually something to be concerned about, unless the mileage drop continues.

 

Next...While tires can always be a factor on fuel mileage, going from a summer only tire to an all season would generally increase mileage, since summer only tires are "stickier" (apples to apples). However, that can not be determined over the Internet, since we have no idea what summer-only tires you had before, and which all-season tires you now have installed.

 

Next...As you said, it is the rough running and "dieseling" that is more of a concern. When you state "dieseling", what exactly is happening? Is the engine still running for a short period after you have turned off the ignition? Just want to be sure we are all working with the same terms and definitions.

 

Next...at ~105,000 miles, it would be a good idea to change your spark plugs (where we all came into this conversation...lol). Yes, the Maintenance Schedule does not require it, but I would highly recommend it. Again, that alone may take care of your 0.9mpg drop.

 

Concerning OTC "fix in a bottle" products: Certain top shelf products, such as Chevron's Techron, are proven to help clean fuel injectors. I am not familiar with a "Dr Injector ultrasonic bath" for injectors, so will need to leave testimonials for that to other members.

 

Also...Is your 2016 MKZ covered by any type of ESP warranty?

 

Get back to us with more information and good luck.

Edited June 6, 2021 by bbf2530

[reverendalc]

Let’s move past the gas, I’m not concerned about it, unless the 2.0 doesn’t like ethanol. 
 

summer tires -> all season tires wasnt my main consideration; it was very expensive tires versus less expensive tires. 
 

my drop of .9mpg isn’t seasonal or from a change in driving habits or equipment use. I’ve had this car for years and I’ve always been at least 41.7, and I expect it to hit 40.9 any day now. It’s been descending over the course of a year. 
 

when I say dieseling, I mean the occasional run-on. It’s not very long and definitely not every time, but it’s there. Sometimes the starts are a little sloppy too… like it’s clamoring to start.  The car performs just fine though. It also sounds much louder than it used to. 
 

originally it was just the clamoring to start, and I had some motor mounts replaced under warranty, but my Lincoln ESP expired at 100,000 /-:  

 

at any rate, I’m going to change the plugs and possibly the coil packs, and I’ll give that Techron stuff a whirl. 

Edited June 6, 2021 by reverendalc

[bbf2530]

56 minutes ago, reverendalc said:

Let’s move past the gas, I’m not concerned about it, unless the 2.0 doesn’t like ethanol. 
 

summer tires -> all season tires wasnt my main consideration; it was very expensive tires versus less expensive tires. 
 

my drop of .9mpg isn’t seasonal or from a change in driving habits or equipment use. I’ve had this car for years and I’ve always been at least 41.7
 

when I say dieseling, I mean the occasional run-on. It’s not very long and definitely not every time, but it’s there. Sometimes the starts are a little sloppy too… like it’s clamoring to start.  The car performs just fine though. It also sounds much louder than it used to. 
 

originally it was just the clamoring to start, and I had some motor mounts replaced under warranty, but my Lincoln ESP expired at 100,000 /-:  

 

Hi rev. We are trying to help you, blindly over the Internet, so...

 

We already moved past the gas, by stating it would not be a concern or the cause of your issues. But you mentioned "regular unleaded" fuel again.

 

No one stated that "summer tires -> all season tires" were a "main consideration" of yours.

You stated (to Multitask), "it ’s interesting that you mention tires!  Around the time I noticed my mileage slowly declining, I DID put new tires. I had some excellent summer tires, but the roads are so continuously wet here that I opted for an all-season tire. I would imagine that tires could easily account for a .9mpg decrease in economy." So you were asking if an "equipment change" may have affected your mpg's.

In reply, I stated that the switch you made, from (soft/ sticky) summer-only tires to (harder/less sticky) all-season tires would most likely result in an increase in fuel economy (apples to apples in tires) not a decrease. However, again, this is all blind Internet diagnosis, since we have no idea what tires were actually on your car before or now. So we can also move past the tire question.

 

The reality is that a drop from 41.9/41.7 mpg to 41.0 mpg is negligible. It is a non-issue.

 

And another reality is, none of us know what the reason/reasons may be for your negligible drop in mpg's, so nothing mentioned can be dismissed out of hand. And "driving habits" were not mentioned. Driving environment was, but they are two very different subjects.

 

So the only actual problem you currently have is the rough running and "dieseling". Therefore, at 105,000 miles, since you do not know what the cause is, the smart move would be to replace the spark plugs with the correct Motorcraft plugs and use a bottle or two of Techron or a similar quality fuel injector product to clean your injectors. And replace the coil packs while you are at it, since you stated that the price of new coil packs is not an issue for you.

If those measures do not help, try "Dr Injector ultrasonic bath", if you or anyone else actually has any good experiences with it.

If that does not help, then it may take a professional intervention/diagnosis by the Service Department at your Lincoln Dealer or an independent shop you trust.

 

Change your spark plugs (and coil packs, if you like), run a bottle or two of fuel injector cleaner in the next two full tanks of fuel, then get back to us and we can move from there.

 

EDIT- Battery degradation beginning, due to age alone, could explain the negligible drop in mpg's. But again, it does not explain the rough running/"dieseling".

 

Keep us updated and good luck.

Edited June 6, 2021 by bbf2530

[reverendalc]

I feel like this is getting a little combative for some reason.

 

Indeed the purpose of the thread was to resolve the rough idle. Gas and tires were mentioned in passing with regard to a drop in mpg that corresponds with the presentation of rough idle, but not suggested to be the culprit.  I know you didn’t specifically say driving habits, but I felt it would be worthwhile to exhaustively rebut any potential causes (both named and unnamed) for my drop in mpg that are external to the ICE’s operation. 
 

for edification, Dr Injector is a string of retail businesses in my locale that offer fuel injector cleaning services.  I haven’t used them personally, but many claim that their service is comparable to replacing the injectors at a fraction of the price. 
 

anyhow, your summation of my summation is correct, and I’ll report back after I’ve had a few bottles of Techron and new plugs. 
 

cheers

[bbf2530]

15 minutes ago, reverendalc said:

I feel like this is getting a little combative for some reason.

 

Indeed the purpose of the thread was to resolve the rough idle. Gas and tires were mentioned in passing with regard to a drop in mpg that corresponds with the presentation of rough idle, but not suggested to be the culprit.  I know you didn’t specifically say driving habits, but I felt it would be worthwhile to exhaustively rebut any potential causes (both named and unnamed) for my drop in mpg that are external to the ICE’s operation. 
 

for edification, Dr Injector is a string of retail businesses in my locale that offer fuel injector cleaning services.  I haven’t used them personally, but many claim that their service is comparable to replacing the injectors at a fraction of the price. 
 

anyhow, your summation of my summation is correct, and I’ll report back after I’ve had a few bottles of Techron and new plugs. 
 

cheers

 

Hi rev. It may have seemed to be getting a "little combative", because too much time was being spent to "exhaustively rebut", instead of taking the advice offered concerning replacing the spark plugs, Techron, coil packs etc.

 

So now that we have moved past that, please keep us updated as to the progress made after replacing the plugs and a few bottles of Techron.

 

I had also edited my previous reply to mention battery degradation, in case our replies crossed in the mail and you did not see that.

 

Good luck.

Edited June 6, 2021 by bbf2530

[drolds1]

EFI-equipped engines should not be running on (dieseling) after shutoff.   Fuel and ignition sources are shut off.  It's not a carbureted engine in this respect. What is possible is that at 105K, there are carbon deposits in the head and one or more leaky injectors is allowing fuel to drip into the combustion chamber where a carbon hot-spot is igniting it.  So, it may very well be worth your while to investigate the injectors and run the Techron through your engine.  These factors could also account for the rough running and hard starting.  Since they Hybrid ICE is not a turbocharged engine, there's no danger if damaging a TC.  Note that a FI cleaning is not going to cure a leaking injector if that, in fact is your issue.

 

 

[bbf2530]

12 hours ago, drolds1 said:

EFI-equipped engines should not be running on (dieseling) after shutoff.   Fuel and ignition sources are shut off.  It's not a carbureted engine in this respect. What is possible is that at 105K, there are carbon deposits in the head and one or more leaky injectors is allowing fuel to drip into the combustion chamber where a carbon hot-spot is igniting it.  So, it may very well be worth your while to investigate the injectors and run the Techron through your engine.  These factors could also account for the rough running and hard starting.  Since they Hybrid ICE is not a turbocharged engine, there's no danger if damaging a TC.  Note that a FI cleaning is not going to cure a leaking injector if that, in fact is your issue.

 

 

 

Hi drolds1. Ooooo...thanks for catching that. I had a brain cloud and it sort of went right over my head that reverendalc's MKZ is a hybrid (and therefore not turbocharged). So my warning about not using induction system services was unnecessary.

 

Good luck.

[drolds1]

2 hours ago, bbf2530 said:

 

Hi drolds1. Ooooo...thanks for catching that. I had a brain cloud and it sort of went right over my head that reverendalc's MKZ is a hybrid (and therefore not turbocharged). So my warning about not using induction system services was unnecessary.

 

Good luck.

I've certainly had my share of those, and they're coming more frequently these days.?

[reverendalc]

Plugs not looking so great. 
 

particularly plug 3, it’s moist. Not terribly. 
 

grabbed a bottle of Techron, fingers crossed

[reverendalc]

So I’m not really realizing any improvement in the sound or feel of my ICE. obviously not enough time has elapsed for the fuel system cleaner to be consumed, but the coils looked fine. 
 

injectors (cleaning or replacement) aside, and assuming that my coils are fine, what else could it be?  I’m no mechanic… I’m also curious what a light coating of oil (presumably) on plug 3 means. The tip was dry, and the well was clean/dry too

[Multitask]

I take it that you pulled them, cleaned them and put them back?

are they the OEM's ?  At your mileage, might have been a good time to change them out.

 

one of them looks a little burnt at the socket... not a mechanic, so I'm not sure if that is good or bad... I'm just pointing out that it's only 1 of them

[reverendalc]

Lol, yeah they’re OEM and I did replace them with OEM. two were kind of baked around the collar, I’m not sure what that might mean either.