running rough, need advice

[Sactown]

Hi all, I've been away for a while but still lurk here every so often as life permits and still enjoying my MM... well that is until it started running rough recently. Here's some details and what's been done thus far, but still not resolved.

-car is stock
-82K miles
-no check engine light, no codes
-same gas as always

Engine starts up in the morning and runs fine while cold, but once warmed up it's a dog at low RPMs. Rough when idling and worse when driving like when it goes into 3rd and is about 1-1.5K RPMs and shakes when I give it some throttle but runs OK once over about 2K RPMs. Problem was slight at first and did some cleaning:

cleaned:
-throttle body
-MAF
-K&N Air filter
-fuel cleaner additive

-No change- So I threw some parts at it that I didn't mind doing anyway:

replaced:
-fuel filter
-EGR
-IAC
-MAF

-No change- well not exactly, the problem seems to be getting worse.

Around town I run in 2nd now just to keep the RPMs up and it does OK but for now I'm just test driving it until I get this resolved.

I've considered other things like fuel pump, fuel pressure sensor, plugs, coils, O2 sensors but not much makes sense being a cold vs hot engine situation unless something is failing only when it gets hot which is possible but not sure how to test other than replace. Also wonder about air intake leaks, band clamps are tight and not sure how to check beyond that.

I've poked around several threads but situations seem a little different so decided to start up my own which may help someone else.

Any thoughts/previous experiences appreciated.

[RubberCtyRauder]

If k & n filter had too much oil, it will coat the maf. It's common with oil filters to be overoiled and cause running issues

[Sactown]

If k & n filter had too much oil, it will coat the maf. It's common with oil filters to be overoiled and cause running issues
Yes, well as mentioned I both cleaned and replaced the MAF so It's hard to think that's the issue here. Besides, I've done K&N filters for many years on multiple cars and no previous problems as such. I'm careful to not over oil the filters.

[slickster]

Was the plugs ever replaced? Most common issue with what ur experiencing is coils. Maybe get one new one then try eatch slot see if it goes away

[Turbov6Bryan]

Pull the plugs, are they clean and white or dark and nasty?

[RubberCtyRauder]

No problem, glad you are aware, many K and n users are not

[Sactown]

I don't mind changing plugs, they're due for replacement soon anyway and they are original. But is it common on a MM for that to run good cold but bad when hot? Other vehicles I've changed plugs on were running poorly at all temps.

[Sactown]

Was the plugs ever replaced? Most common issue with what ur experiencing is coils. Maybe get one new one then try eatch slot see if it goes away

If I was getting a coil/plug misfire wouldn't that trigger a CEL code?

[Turbov6Bryan]

82k on the plugs and original coils?

With my experience working on DIS cars trucks and equipment, the coils work fine until hot OR UNDER A LOAD .heat is a major factor that kills a coil.

So yes, a coil or more than one may warm up from driving, then start acting up

Usually they don't just flatline, they breakdown over time.

Yes you should get a code if you drive it enough, pull the plugs let's see what they look like

[Mike D Mechanic]

I had some what similar problem no CEL long story short had to replace my coils to resolve my issue. had less than 50K mi on my MM. good luck sorting it out

[Sactown]

OK, helpful feedback. Plugs and coils was on my to do so I'll give that a go and see what happens. Will also report back on the condition of the old plugs.

Speaking of coils, rockauto doesn't list motorcraft for those, but says the DENSO 6736008 Coil on Plug is the Original Equipment Part. Is this true?

Also is there anything else I should look at/get for this plug/coil service? Haven't done this yet on my MM and might as well ask now.

[RubberCtyRauder]

Plugs use NGK TR6

Sparta performance has coils here in the vendor section. They are listed under the Gt500 parts. Send him a email or message here

[Turbov6Bryan]

http://www.rockauto.com/m/mobilecatalog.php

I used the mobile app for 2003 marauder and motorcraft ones are listed on the site

[8UWITH6]

Verify fuel pressure. Also do not overlook checking the transmission fluid. Torque converter shudder can be mistaken for a miss or running rough. I did read your symptoms and realize you said it runs rough at idle warm. Just eliminate a possibility and check your trans fluid. HTH

[1Marauder]

Sactown... In Sac? You LURKER!

Why you not say hello? Let's meet up!

[Sactown]

Plugs use NGK TR6

Sparta performance has coils here in the vendor section. They are listed under the Gt500 parts. Send him a email or message here
Thanks for the suggestions, what do you like about these over motorcraft?

[Sactown]

http://www.rockauto.com/m/mobilecatalog.php

I used the mobile app for 2003 marauder and motorcraft ones are listed on the site
Interesting, thanks for spotting that. I just contacted them to clarify, I doubt there's a different coil between the '03 and '04

[Sactown]

Verify fuel pressure.
I guess that would eliminate the fuel pump question. But no clue how to do that but first time for everything. :o I'll poke around to learn up, but if you have a preferred tool/method I'm all ears.


Also do not overlook checking the transmission fluid. Torque converter shudder can be mistaken for a miss or running rough. I did read your symptoms and realize you said it runs rough at idle warm. Just eliminate a possibility and check your trans fluid. HTH
I will do that, thanks. Actually it wouldn't hurt to change it out either. I want to go through and put in all new fluids regardless.

[Sactown]

Sactown... In Sac? You LURKER!

Why you not say hello? Let's meet up!

Sounds good once it's running smooth again :beer:

[RubberCtyRauder]

A lot of members here use the NGK TR6, it' a one step colder range plug as I have supercharger but it is also fine for naturally aspirated. There was just a plug question last week and a lot of members replied NGK TR6.. Tommy at Sparta sells Motorcraft. he's a vendor here and a lot of people been happy with him. Motorcraft coils are usually recommended.

[Zack]

From a stop, floor it to about 90+ mph
This gives the PCM enough time to detect a misfire (from a bad coil)
It will flash the check engine light and store the code

[1Marauder]

From a stop, floor it to about 90+ mph
This gives the PCM enough time to detect a misfire (from a bad coil)
It will flash the check engine light and store the code

Next time I get pulled over... I am using this line above

[Sactown]

Next time I get pulled over... I am using this line above
Yea, I was wondering where/when I'd do that and not get busted. I'm near the 50 and the CHP is buzzing that hwy from Sac to Placerville way too often to give that a try. Maybe one of the rural roads to the south east. I could at least try it to about 70 mph.

[SteelQualityMan]

I would definitely look at the coils. I have had two of them fail (separately), and only one of them gave me a CEL. Electrical and electronic parts are notorious for working at one temperature and then failing at another.

Sent from my LG-H901 using Tapatalk

[piratediver]

Experienced the exact same symptoms with my 94 cougar with 4.6l. SUDDEN onset rough running at low rpm. full tune with plugs and cops and ran fine after . no further problems.

[tbone]

You also may have water in a spark plug well if you wash your motor and the cop cover seal is bad. The engine will seem to idle fun but run like crap while driving if you have a bad coil or H2O. And you will get horrendous fuel mileage.

[HotRaud90]

82k on the plugs and original coils?

With my experience working on DIS cars trucks and equipment, the coils work fine until hot OR UNDER A LOAD .heat is a major factor that kills a coil.

So yes, a coil or more than one may warm up from driving, then start acting up

Usually they don't just flatline, they breakdown over time.

Yes you should get a code if you drive it enough, pull the plugs let's see what they look like


I had some what similar problem no CEL long story short had to replace my coils to resolve my issue. had less than 50K mi on my MM. good luck sorting it out

What these guys and others have said.

I had issues similar to the ones you mentioned. Under load and in lower RPM ranges I would get a lot of stuttering and hiccups. The motor would bog down and there was lack of power and consistent firing. No CEL whatsoever.

After replacing the coils with correct FoMoCo coils and NGK TR6 plugs (one step colder), all those issues vanished. I found the best prices possible on eBay, but it depends on where and when you look.

[Sactown]

Thanks everyone for your input.

New coils and plugs are on their way, will have them here next week and will report back results. I wanted to change them out anyway so it's worth doing regardless.

[tbone]

The retaining clips on the cop connectors tend to get old and brittle and sometimes snap off. I put a little silicone around the edges on the couple that broke on my car and allow to dry before driving. It pulls off fairly easily if you ever have to remove them again. One day I will replace them all.

[1Marauder]

Sounds good once it's running smooth again :beer:

I have an EXTRA SET of the suggestted TR6 one degree cooler plugs if you want to try them out with some new coils. The old "try before you buy." I found them on sale on eBay. Sell them to you at cost if it helps fix your car.

Also if doing this yourself (I assume) I 'd love to help! I will need to do mine soon too!

[Sactown]

The retaining clips on the cop connectors tend to get old and brittle and sometimes snap off. I put a little silicone around the edges on the couple that broke on my car and allow to dry before driving. It pulls off fairly easily if you ever have to remove them again. One day I will replace them all.

I'll watch out for that thanks.

[Sactown]

I have an EXTRA SET of the suggestted TR6 one degree cooler plugs if you want to try them out with some new coils. The old "try before you buy." I found them on sale on eBay. Sell them to you at cost if it helps fix your car.

Also if doing this yourself (I assume) I 'd love to help! I will need to do mine soon too!

Thanks for the offer but I've got the plugs now and the coils on the way. I've got this task covered and I look forward to connecting when she's running right again. What part of town are you at?

[1Marauder]

Sierra Oaks... Near (across the river from) Sac State.

Fair Oaks and Fulton Ave. You?

[Sactown]

Sierra Oaks... Near (across the river from) Sac State.

Fair Oaks and Fulton Ave. You?

Near Rancho, pretty close. Surprised we haven't crossed paths in town, I've driven those 80k miles mostly local since new. Only time I met a MM owner unintentionally was at Costco. How long you been driving a MM?

[Sactown]

OK, coils arrived today and figured I'd get the process started while I had a bit of light still outside. Figured I'd at least get the covers off and pull the old coils. Yanked the drivers side and all went well...but the passenger side was a different story :( Here it is in picts:

underside of covers::(
http://i.imgur.com/6NA3ZrM.jpg


cylinder 2::) (1,2,4,5-8 looked shiny down low like this)
http://i.imgur.com/zhXptMk.jpg


cylinder 3::(
http://i.imgur.com/Dk3yAa2.jpg

coils 2 and 3::(
http://i.imgur.com/jlKYvHh.jpg


Didn't yank any plugs yet, had to come in to take care of some business and the skeeters were eating me alive. But what I found here obviously doesn't look good. The plug wells and coils for 1, 2 and 4 (and 5-8) look clean, but #3 looks all rusty and clearly the whole bank side was contaminated with moisture and a bit of oil as well.

FTR I have never rinsed down my engine compartment, I just wipe things down with a moist rag from time to time.

I'll be pulling the plugs tomorrow, will post those picts also when I do. At least it seems like we're barking up the right tree.

This is definitely new territory for me on the MM, is this some head FUBAR here at #3 or just a cover leak (but from what I don't know)? Thoughts?

[tbone]

One of your O rings on the valve cover is leaking oil into the well. Common.

[Sactown]

One of your O rings on the valve cover is leaking oil into the well. Common.

But the #3 well looks rusty rather than oily...it was hard to take the pict, I'll see if I can do better pict tomorrow.

BTW, are you referring to the spark plug gasket or something else? Thanks.

[tbone]

It looks like you found the issue with the rough running. Now keep an eye on it after you put it all back together.

I theorize that any condensation in the motor is blowing past that O ring with every startup over the years and causing the corrosion. Too bad it's the passenger side. The cover is a pain to get off.

[Sactown]

You may have had some moisture in there. But if the well was not still partially filled with water, it should not be fouled. Still, it looks like you found the issue with the rough running. Now keep an eye on it after you put it all back together.

The wells definitely look dry inside, even the ugly #3. There was condensation though that I wiped off the coils and inside cover, passenger side only, driver side was clean and dry. I'd like to take care of the o-ring oil leak, but not sure which part that is.

[tbone]

When you buy a valve cover gasket set, you get 8 O-rings as well. They seal the valve cover to the plug well, just above the top of the plug.

[Sactown]

I theorize that any condensation in the motor is blowing past that O ring with every startup over the years and causing the corrosion. Too bad it's the passenger side. The cover is a pain to get off.

Sounds like you're referring to the spark plug gasket, at least that's what my service manual is calling it. Page 303-01B-12 (part 6C527).

[Sactown]

When you buy a valve cover gasket set, you get 8 O-rings as well. They seal the valve cover to the plug well, just above the top of the plug.

Ah, thanks :)

[Sactown]

Is the shiny sleve in the well replaceable as well? It's gonna bother me having that rusty one in #3 lol

[tbone]

Look at the pic above. You can see the spark plug and the seat of the o ring that fails.

[tbone]

Is the shiny sleve in the well replaceable as well? It's gonna bother me having that rusty one in #3 lol

That's the head.

[Sactown]

Look at the pic above. You can see the spark plug and the seat of the o ring that fails.

OK, I'm seeing it


That's the head.

Thanks. I guess it will stay rusty for now.

[tbone]

You could rub some cloth or something in there. Just don't let any crap get into the cylinder.

[Sactown]

You could rub some cloth or something in there. Just don't let any crap get into the cylinder.

the way it looks I think it's past getting clean, but I'll try a little with a q-tip.

[Sactown]

Replaced the plugs and coils and running great once again. I'll be back to post pics of the plugs, #3 plug was loose, all the nasty in that well may be from that. I'm gonna go back in and clean it up and monitor it. Thanks again everyone for all the input!

[Turbov6Bryan]

Yay glad your up and running smooth

[Gerry24]

You're ready to go :burn:

[Sactown]

so here's the plugs, #3 being ugly as if it had blow by or plug gasket leakage, and as mentioned before it came out way too easy.

Any of the plug tips look troubling?

http://i.imgur.com/smrIZq3.jpg

http://i.imgur.com/hII5wsd.jpghttp://i.imgur.com/YjJhQ5F.jpg

http://i.imgur.com/U6sYYQm.jpghttp://i.imgur.com/jUmqTv2.jpg

http://i.imgur.com/kpO1D3R.jpghttp://i.imgur.com/Gp3T4T9.jpg

http://i.imgur.com/XKelEeS.jpghttp://i.imgur.com/4QRh2i0.jpg

[fastblackmerc]

Do it yourself...................... .

https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug

https://www.google.com/search?q=how+to+read+spark+plu gs&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiM5frHrv_KAhXJdj4KH U2XCnMQsAQIHA&biw=1680&bih=953

[Sactown]

Do it yourself...................... .

https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug

https://www.google.com/search?q=how+to+read+spark+plu gs&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiM5frHrv_KAhXJdj4KH U2XCnMQsAQIHA&biw=1680&bih=953

Thanks, yes I had previously referred to this which suggests I'm in the OK to good range http://cx500forum.com/forum/attachments/technical-help-forum/5306d1381684717-spark-plug-second-opinion-kerzengesicht.jpg

But I also was interested in how mine are comparing to the experience of other MM owners hence posting the picts.

[Marauderjack]

You are OK......glad you got it fixed!!:beer:

[Sactown]

You are OK......glad you got it fixed!!:beer:

Thanks for the feedback, much appreciated. I'll be checking in on the plugs much more frequently now

[Sactown]

Put a few hundred miles on it yesterday and it's been a few years since its run this nice. So glad this got sorted out, nice to have the old beast back, even if it is just stock.
:burn: