Off and on engine miss

[DSG2003Mach1]

the Denso coils have been shown to be rebadged motorcraft, there are posts about it over on the lightning garage facebook group.

It doesn't always set a code for which cylinder is missing. I believe you need something that would perform a power balance test similar to the software a Ford dealer would use to track it down.

 

[Dusten]

Are there any reasonably priced OBD readers that will tell you which cylinder is the issue to quickly narrow down which COP and/or plug may be failing?

No.

Forscan and an expensive obd scanner can do a mode 6

 

[Coosawjack]

What spark plugs are you running??

 

[ArkLightning]

Took a while to get motivated but bought new Autolite coils from Rock Auto and finished installing them today (what a thankless job). Unfortunately the random miss is still there so looks like that $320 didn't do me much good.

Violated my principal of always do the cheap and easy stuff first. So next I'm going back to formula and change the fuel filter since the last time I had a similar but more severe issue like this, that cleared it up. After that - I didn't install new plugs as the TR-6s only have about 4,000 miles on them. The one I pulled looked fine - but maybe there's an issue with them and I guess I'll spend some more quality time shredding my hands in there.

 

[00L]

Took a while to get motivated but bought new Autolite coils from Rock Auto and finished installing them today (what a thankless job). Unfortunately the random miss is still there so looks like that $320 didn't do me much good.

Violated my principal of always do the cheap and easy stuff first. So next I'm going back to formula and change the fuel filter since the last time I had a similar but more severe issue like this, that cleared it up. After that - I didn't install new plugs as the TR-6s only have about 4,000 miles on them. The one I pulled looked fine - but maybe there's an issue with them and I guess I'll spend some more quality time shredding my hands in there.

That sucks, thankgless job indeed, I'm in the same boat and trying to avoid changing expensive items as well and may just take it to stealership and have them diagnose the cylinder or root cause, did a fuel filter yesterday after reading up on this post and others, but no joy. Ordered a cyber monday special OBD on amazon that claims mode 6, will be here tomorrow and I'll see if I can further diagnose. I feel for you, and am checking this daily to see what the other experts think. Years ago I would have looked forward to a weekend working on the truck, but now I simply dont have the time.

 

[FireGuy]

In your original post you stated that you had changed plugs around 12k, and shortly thereafter you have a slight miss. My guess is that you opted for cheap plugs, as you stated is your mantra, "cheap and easy". My thinking is that your miss is either fuel mixture or a spark issue, with cops being eliminated from the equation. Since spark plugs are less expensive than cops, I am surprised you didn't pull them and add a fresh set. I have found two things to be true. One is that even new plugs can miss and in fact will miss under load more often than thought. Secondly, running any cleaner through the fuel system of a performance vehicle especially would mandate a fuel filter and plug change as these types of additives add deposits on the plug tips.
Take what you will from this but know that what I am telling you has been experienced by me firsthand.

One other item that could be causing slight miss issues is the DPFE on the driver's side. It has vacuum hoses and an electrical plug on it. If it is aluminum, you should replaced it with the revised plastic one. Look for that valve on Rock auto and you can see what it looks like.

I hope that any of this is helpful and you get this resolved. i

BTW, I don't claim to be the smartest guy or a Lightning guru but I am trying to help

 

[ArkLightning]

I replaced the plugs about 2007 or 2008 when I put the 4lb pulley and tune on (would have to check my log to be exact). I've only put about 5,000 miles on it since then. About 4 years ago (around 2014) I developed a miss when I opened the throttle up and a replacement of the fuel filter fixed that. That miss usually manifested itself when the throttle was opened up.

This miss started about 4 months ago and is similar to when the fuel filter was acting up - but not exactly. This time it occasionally misses at idle or just off idle. That is kind of unusual for a fuel supply issue as a fuel supply issue usually will act up when the throttle is opened and increasing fuel demand. Of course high pressure fuel pumps, fuel rails and fuel returns/circulation sort of cloud that theory.

In my experiences with my old muscle cars, a miss under light engine load or idle is usually a bad plug wire - no wires here but I thought maybe a bad cop behaves in a similar fashion. Apparently not in this case but as you point out it might be a plug or plugs.

 

[FireGuy]

Exactly, old muscle car days is where I learned about low end and high rpm misses. 98% of the time it was a fouled plug. On several occasions it was a new plug right out of the box that gave me fits, I just cold not believe that the new one was junk. When they came out with resistance plug wires, it got even worse on damp days. I went to solid copper core Packard wires after that. What you may find will surprise you and don't forget to check all the vacuum lines carefully, they can age and crack, also keep the DPFE in mind, it can mimic or cause misses low to mid range.

 

[ArkLightning]

No joy in Arkansas with a change of fuel filter. I didn't even need to drive it as it was randomly missing at idle after starting it. So, I have a set of NKG TR6/IX plugs which I will put in in the next few days and see what happens. It has the plain (thick electrode) TR6 plugs in it and maybe they just don't last like the iridium electrode plugs. The more frequent missing at idle is making me suspect plugs more now (plus it's about the last of the relatively easy, and straight forward stuff to change).

Fireguy - have you got a picture of this DPFE or a complete name for it so I can locate it? If it isn't points, condenser, rotor, jet, float, etc - it's not in my everyday realm.

Thanks

 

[Dusten]

No joy in Arkansas with a change of fuel filter. I didn't even need to drive it as it was randomly missing at idle after starting it. So, I have a set of NKG TR6/IX plugs which I will put in in the next few days and see what happens. It has the plain (thick electrode) TR6 plugs in it and maybe they just don't last like the iridium electrode plugs. The more frequent missing at idle is making me suspect plugs more now (plus it's about the last of the relatively easy, and straight forward stuff to change).

Fireguy - have you got a picture of this DPFE or a complete name for it so I can locate it? If it isn't points, condenser, rotor, jet, float, etc - it's not in my everyday realm.

Thanks

Its right next to the egr on the blower with a connector on it.

 

[ArkLightning]

I found it with Google _ I'll check it out.

I have the metal type. Hoses look fine. The truck only has 17k miles on it.

My hands are about healed up from installing the COPs so I'll probably try to start on the plugs this weekend.

 

[FireGuy]

Glad you found it, thanks Dusten for the back up. You should replace it because they are prone to problems and will corrode internally. Found them on Rock Auto, anywhere from $33 to $60. It's under exhaust and emission. I know what you mean about the hands healing, my Lightning is a demanding bitch that wants blood whenever I work on her. seriously, I have a saying that the job is not done until I bleed on it.
As a footnote, the two vacuum hoses that attach are different sizes in diameter.

 

[ArkLightning]

OK - thanks. Let me see how the plugs go first. At this point I have most of my faith shifted over to the plugs being at fault for the miss. But I understand what you are saying that the DPFE is a maintenance item.

 

[ArkLightning]

Well, the engine appears to be fixed. I replaced the plugs today but the plugs looked good as apparently were the old coil over plug units. What I did find while installing the plugs was that a large rubber line was running lengthwise down the right valve cover and as I moved it aside I was staring right down the PVC grommet hole with no PVC valve. It was laying loose several inches away. No telling how long it has been off or how it got that way - I'm the only person who touches the truck. It could have been off for a few years as I only put about 4-500 miles a year on it. I had been noticing that I was collecting zero oil in my oil cannister which was puzzling me but I hadn't done anything to investigate. Probably need to change the oil again - been about a year. But seems to run fine now.

Boy the plugs were a bitch to get out even through I coated the threads with anti-seize when I changed them years ago. I made up a long straw out of windshield washer tubing and put it on the built in spray straw on a can of WD40 and soaked them down with it to get them to spin out. That regular anti-seize stuff apparently won't stand up to high temps so I installed these with copper, high heat anti-seize paste.

 

[FireGuy]

Sounds like you have got it figured out, congrats. Hopefully, it will be a long trouble free run until the next maintenance comes up. Enjoy