Misfire On All Cylinders?

beviking · Jun 14, 2012

Had a stumble after getting into 2nd gear so took her to the dealer. They say it's misfiring on all cylinders? Haven't noticed any difference in driving though the car sounds different. 2012 gt, 6spd, only mod was JLT oil separator but that was a couple months ago. Any ideas what this is, is caused by?
Thanks!

bigb427 · Jun 14, 2012

Did you get the car back already or are they still working on it? Missfires can be caused by many things. They didn't tell you any other info? I would have to imagine it is still under warranty so I wouldn't worry about it unless the car still has the same concern after you get it back.

beviking · Jun 14, 2012

Actually dropped it off so they can have it for the day. Car only has 1800 miles. Seems weird that it runs drives so well, unless it misfired on all cylinders at different times? The guy checking me in asked if it was still driving the same, I said yeah, drives great and I don't know how it can be misfiring? Another gentleman asked me 3 different times/ways if I modified the air intake, which I haven't yet but I did tell them about the separator and they didn't seem too concerned about it. Let you know tomorrow what they find out.

beviking · Jun 15, 2012

Problem solved, why I didn't think of this...it was the ckp connector. It was loose. They think it was not fully seated and vibrated loose. They removed it, cleaned, applied sealer and reattached it, problem solved. View attachment 147997 What the heck is the ckp connector????

bigb427 · Jun 15, 2012

CKP = Crankshaft Position Sensor. I am surprised you didn't have a problem with the car stalling being that's what the problem was. That could definitely cause problems if the sensor output was erratic to the PCM. Good to hear it's fixed!

mustangmike6996 · Jun 23, 2012

ummmmmmmmm im pretty sure they made that up lol. i mean, anything is possible but they clip in, the chance of vibrating loose is almost 0% if it "vibrated loose" that would mean the clips are broken or it was not fully seated during the build. Also, installing sealer is not the best method for repair on a brand new car. The connectors have the weather-pack seal to keep the elements out, if they got sealant on that, you will more than likely be buying a new seal if it ever gets unplugged.

bigb427 · Jun 23, 2012

The OP stated right in his last post the connector "wasn't fully seated". I have seen this many times on various connectors of all types on vehicles with low mileage. It's not a matter of them becoming unlatched, it's that they never were fully latched to begin with.

The concern was a little unusual as I stated in my previous post, but not out of the question. The matter of the sealer leaves me scratching my a head a little though. There is no need for it, albeit dielectric grease may be all that was used, if so, no harm done.

mustangmike6996 · Jun 24, 2012

bigb427 said:
The OP stated right in his last post the connector "wasn't fully seated". I have seen this many times on various connectors of all types on vehicles with low mileage. It's not a matter of them becoming unlatched, it's that they never were fully latched to begin with.

The concern was a little unusual as I stated in my previous post, but not out of the question. The matter of the sealer leaves me scratching my a head a little though. There is no need for it, albeit dielectric grease may be all that was used, if so, no harm done.

i understand he said it was not fully seated (im pretty sure the dealer was the one that "found" it)

what i was saying is: a lot of times in dealerships for warranty claims, techs will "find" something wrong even if they cannot verify the complaint so they will make some sort of repair hours on the car. With a loose crank plug i can see it causing a misfire, but on a more serious level. with no crank input there would have been a check engine lamp for no crank signal voltage, the fuel injectors will not pulse without a crank signal. if an injector wont pulse (even if it only happens a few times) you will get p0301-p0308 for the effected cyl. hell, depending on how "loose" it was, he really could have had a crank-no-start.

bigb427 · Jun 24, 2012

mustangmike6996 said:
i understand he said it was not fully seated (im pretty sure the dealer was the one that "found" it)

what i was saying is: a lot of times in dealerships for warranty claims, techs will "find" something wrong even if they cannot verify the complaint so they will make some sort of repair hours on the car. With a loose crank plug i can see it causing a misfire, but on a more serious level.

I agree with that.

mustangmike6996 said:
with no crank input there would have been a check engine lamp for no crank signal voltage, the fuel injectors will not pulse without a crank signal. if an injector wont pulse (even if it only happens a few times) you will get p0301-p0308 for the effected cyl.

In theory you are correct. In actuality - not necessarily. I have seen more than a few vehicle's with crank sensors that didn't work and they had no codes in them at all. As far as missfire codes, it depends on how frequent the missfire has occurred as to whether a code sets or not. I get vehicles in all the time that have an intermittent miss, and they don't have any codes at all.

mustangmike6996 · Jun 26, 2012

im not disagreeing with you...

im the 10 years i have worked on cars at a dealership level i have only seen a Ckp sensor not throw a code when its completely failed. for example (and i know its a different make/model ect) With the ML platform Benz the crank sensors would get hot and open electronically. this would cause a crank no start. normally this would not have a DTC.

I have also had many other concerns cause a P0300 or give symptoms of a misfire with no fault. normally it is things like, bad gas, air leaks or other mechanical related issues.

What i have a hard time believing is that the stang would have made it 1800 miles with a partially plugged in connector, misfire enough to be a concern and never set a DTC.

im jut wondering if there are any other 5.0 owners with common problems or if it was the only one thats been to the dealer yet

bigb427 · Jun 26, 2012

I agree with everything that you have stated. It is definitely unusual and it's possible something entirely different was wrong with the car. It's impossible to know for sure, but what the dealer told the OP is not impossible. If the OP is reading this, I wouldn't worry about any of this as long as the car is running properly.

I have not had a 5.0 with this concern myself or heard of anyone else having the same concern either. I have however seen a few cars that have had some repairs done and needed the missfire monitor neutral profile correction relearned. These vehicles have returned shortly after having engine or clutch repairs with missfire codes. While it doesn't pertain to the OP there is also a TSB on early 2011 5.0 Mustangs for missfire codes in which reprogramming the PCM is called out.

beviking · Jun 27, 2012

Hmm, just wanted to point out that I didn't have the problem for 1800 miles, it all happened within...oh, a couple weeks, think it rained so not much driving...maybe a hundred or two hundred miles? Made sense that the plug wasn't fully seated and it took 1600 miles to vibrate loose. On the other hand, if the clip or other mechanism that holds the connector in place broke and they had to use a sealer/adhesive, I would liked to know that. I can look next time I'm under the car I guess. Also, I had just received my SCT tuner the day before I took it in and checked for codes...there were none. Been about 500 miles and the problem has not re-occurred. I installed a Steeda CAI and loaded the Steeda tune after about 250 miles, so about 250 miles with that on.

stang8urimport · Jun 27, 2012

I've been doing the car repair thing for quite a while... And I think I'm successful. But I am always hesitant to give advise and/or an opinion because there is always someone that will either prove you wrong or argue with you on internet forums. So I have just learned to keep my mouth shut. It works out a lot better that way.

To the OP... I'm very glad the dealer fixed your issue. It's always nice to drive away from the dealer with a correctly functioning car.

Fireball906 · Jul 12, 2012

mustangmike6996 said:
ummmmmmmmm im pretty sure they made that up lol. i mean, anything is possible but they clip in, the chance of vibrating loose is almost 0% if it "vibrated loose" that would mean the clips are broken or it was not fully seated during the build. Also, installing sealer is not the best method for repair on a brand new car. The connectors have the weather-pack seal to keep the elements out, if they got sealant on that, you will more than likely be buying a new seal if it ever gets unplugged.

Just got my 2012 gt back with 15,500 on it, two road trips and one of the cam position sensors "vibrated loose". Now there is electrical tape on all 4 of my cam sensors. Not sure why it didn't happen sooner either.

Misfire On All Cylinders?

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