Misfire under load.

[Brenneman2385]

Since you are only getting a misfire code, how about replacing the offending Chinese coil with a real one, like one of the Motorcraft ones you took off? Maybe it's just a bad coil. Did you change the boots too when you did the plugs? I'm hoping your problem has nothing to do with the VCTs.

Trainmaster,

Thanks for the response. I installed new boots as well. I can swap the coils at some point to determine if the coil is the issue. I thought that the accel coils were an upgrade from the motorcraft coils, that is why I purchased these. The misfire is not throwing a code, this is just from the mode 6 data that I can tell it was misfiring.

 

[1955moose]

No their not an upgrade, to the contrary, their a cheap Chinese knock off that uses the old Accel name. The Ford originals are the strongest and best. But at $75.00 a pop, most won't spend that kind of money. If your only problem is #3, then try coil first, pull spark plug on #3, do compression test of that one cylinder, you'll have to disarm ignition. Pulling crank position sensor will do, after if all checks out, check plug going to #3 injector, then finally replace that injector. Examine spark plug of #3 very carefully, easy to crack porcelain, or damage gap, or electrode. #3 for some reason is a prime suspect for misfires on these motors. Don't exactly know why? Might have to do with firing order.

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[Brenneman2385]

No their not an upgrade, to the contrary, their a cheap Chinese knock off that uses the old Accel name. The Ford originals are the strongest and best. But at $75.00 a pop, most won't spend that kind of money. If your only problem is #3, then try coil first, pull spark plug on #3, do compression test of that one cylinder, you'll have to disarm ignition. Pulling crank position sensor will do, after if all checks out, check plug going to #3 injector, then finally replace that injector. Examine spark plug of #3 very carefully, easy to crack porcelain, or damage gap, or electrode. #3 for some reason is a prime suspect for misfires on these motors. Don't exactly know why? Might have to do with firing order.

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Thanks for all of the advice. If it is warm tomorrow and not raining I will check this. This gives me a good checklist, I will report back with my findings after all of this is completed.

Thanks again!

 

[gixer2000]

Thanks for all of the advice. If it is warm tomorrow and not raining I will check this. This gives me a good checklist, I will report back with my findings after all of this is completed.

Thanks again!

Keep in mind unplugging things is a good troubleshooting method(injector/coil) to see if anything changes or not. If you unplug a coil and it runs the same at idle you may have found the issue once you confirm its getting fuel.

 

[Brenneman2385]

This makes even less sense now. I completed the exact same drive, return home and this time there were no misfires read by the scanner, however same issue with shaking at stop lights, and RPM drops to 540 – 560. Thoughts?

 

[gixer2000]

This makes even less sense now. I completed the exact same drive, return home and this time there were no misfires read by the scanner, however same issue with shaking at stop lights, and RPM drops to 540 – 560. Thoughts?

Making me wonder if you have a stuck phaser. Any noise at start up?

 

[1955moose]

Sounds more like a vacuum leak. Smoke the motor, you'll be surprised where smoke emanates from. Thing is you keep getting that #3 cylinder code. If I was working on your truck, I'd break it down there. Theirs a reason why that scanner keeps popping up that cylinder. It might be other things, seen that, but you've got to eliminate that cylinder, don't get swayed by other things. These SUVs will take you all over the place if you let it.Seen members change out $1,000 worth of parts, just cause they were guessing, and had a new master card. Check simple things like the boot spring making a clean tight connection, it doesn't take much to cause misfires.

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[TobyU]

Swap #3 coil to #1 or 4 or even 5 or 6 and see if miss moves.
If not try a new plug next as Moose said. Even a slightly dropped one in the box can damage it.
Or try one of old coils you pulled out.

Then if nothing proved by then do compression test.


Is this a constant miss or intermittent? If constant I would pull out plug asn see if the cylinder does the correct blow blow blow blow when you crank it even if you don't have a comp tester. Try to put finger or rubber hose into plug well. It should NEVER suck in hard. Only blow.

 

[Brenneman2385]

Swap #3 coil to #1 or 4 or even 5 or 6 and see if miss moves.
If not try a new plug next as Moose said. Even a slightly dropped one in the box can damage it.
Or try one of old coils you pulled out.

Then if nothing proved by then do compression test.


Is this a constant miss or intermittent? If constant I would pull out plug asn see if the cylinder does the correct blow blow blow blow when you crank it even if you don't have a comp tester. Try to put finger or rubber hose into plug well. It should NEVER suck in hard. Only blow.

Hello TobyU, this only happens once the truck is at operating temperature, in gear, at a stop. If you place the truck in park or neutral it goes away, and if you slightly give it gas at a stop to raise the RPM up to 700+ it goes away. However in gear, at operating temperature, at a stop the RPM will drop as low at 540 and the truck starts shaking.

 

[bobmbx]

This sounds an awful lot like an IAC failure. I don't know if your engine has an IAC, though. Virtually no engine nowadays has one.

 

[1955moose]

Idle air control valves when they get carboned up will make the motor stall completely. We had one on our Harley rental Dodge go bad. It was brutal. Barely kept running. Idle motors are generally cleanable. Used to do it on my 86 5.0 Mustang, and 89 Lincoln. You spray and brush out the carbon, and throw on a new gasket. Even the cheaper ones are $60.00 on up. I'm all for servicing and saving an existing part. And like Toby, I'm cheap! Like most guys, I hang on to my undies until theirs barely a hunk of elastic holding them up. God help the poor nurse that See's them when they haul my carcass into the emergency room, and has to remove them!

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[gixer2000]

This sounds an awful lot like an IAC failure. I don't know if your engine has an IAC, though. Virtually no engine nowadays has one.

No idle air control valve on these.

 

[Brenneman2385]

Hey all,


Well after mentioning the IAC I found that they are no longer on this vehicles. Somewhere I saw cleaning the throttle body, and relearning the PCM from FordTechMakuloco on YouTube. I did this, and cleaned the MAF today and I should have done this when I purchased the truck as it relearned the shift points and shifts much smoother now. It is still dropping to 540 RPM’s, and did get rough for a moment after test driving, but so far once I come to a stop there seems to be a sharp drop in RPM and when this happens it is like a downshift, or load is removed. At first it made me feel like it was going to die, but it has not. I am taking in on a trip tonight for about 200 miles. I am going to monitor and if this issue is still occurring I am going to pull the plug on 3 and inspect, then swap coils with 1 tomorrow. Just wanted to give an update.


Thanks,

 

[1955moose]

Did you ever smoke the intake system to be sure you have no leaks anywhere? The other problem later 3rd editions had, and yours might be one, is a failing throttle body. Usually when they go bad is total dieing of engine. I'm sure you'll hit on it soon.

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[gixer2000]

Did you ever smoke the intake system to be sure you have no leaks anywhere? The other problem later 3rd editions had, and yours might be one, is a failing throttle body. Usually when they go bad is total dieing of engine. I'm sure you'll hit on it soon.

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This is more common the 15+ EB than the 07-14. I haven't seen anyone report a TB failure on the 07-14 but I haven't done any research on it either

 

[1955moose]

Actually Gixer theirs quite a few. Most are 2010 on up models.

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[TobyU]

Hello TobyU, this only happens once the truck is at operating temperature, in gear, at a stop. If you place the truck in park or neutral it goes away, and if you slightly give it gas at a stop to raise the RPM up to 700+ it goes away. However in gear, at operating temperature, at a stop the RPM will drop as low at 540 and the truck starts shaking.

Usually it's not going away, it just can't be felt when in P or N since the idle is a little higher.

This is where the scanner and misfire counts is valuable.

 

[TxOutlaw]

Usually it's not going away, it just can't be felt when in P or N since the idle is a little higher.

This is where the scanner and misfire counts is valuable.

YEP!!! I invested in the OBDII wifi reader and an app... We had the same misfire issue on ours.... Turned out to be #4 coil... Swapped it out and tuned it up and good to go!

 

[1955moose]

Coil's are funny little items. In some cases they won't throw a code, will measure ohms fine during a test. These situations are rare, but do exist. I had an owner of our Honda, Yamaha shop here in Daly City, that had such a problem but more severe. He was working on a Honda 4 cylinder big bike, 900 cc I think. He did all the normal tests on coil, pickup coil and module, but no spark for 2 cylinders. Out of a hunch, he grabbed a coil from his parts dept, and Bam, fired up on all 4. He'd been a top level mechanic, and owned a motorcycle machine shop, so for him to say he was surprised, spoke volumes. That's why we always say here to keep a few known good spares of electrical items. Just because an item test good, doesn't mean it is.

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[Brenneman2385]

Hello All,

Again thank you to everyone whom is participating to help me with this issue. This is getting extremely frustrating. So today I went and smoked the engine directly through the throttle body, no smoke observed anywhere except for a small leak in my input hose. After this I removed the coil and plug from cylinder 3. The plug has no visible issues. I then removed the coil from cylinder 1 and moved to 3, then installed the coil that was on 3 to cylinder 1. The last 2 days I have had about 300 miles on the truck and the low RPM causing the truck to shake happens at every stop, but there are no misfires reported by the mode 6 data. After running the truck with the coils changed it feels to be slightly missing more, the RPM dropped to 484, which is the lowest I have ever seen it so far, but the PCM is still not reporting any misfires. I have not rented a compression tester as of yet, but can not seem to isolate or identify a root issue. Is there anything else that I should be monitoring with the live data that I am not aware of?

Thoughts?