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Discussion Starter · #1 ·
Well well, this brand new car keeps giving me more joy...

I was merging on the freeways day before yesterday when I was sitting high in gear for a minute, waiting for the right time to 'pop out' and pass the slow poke in front of me to get up to speed with the rest of the traffic.

Well, as I go to step on it and make my way, the car does this weird hiccup/stutter; I can't describe it very well as it all happened so fast.

I pulled over turned the car off and had my dad run me out the obd reader; spat codes P0300 301 and 306.

Random misfire and then a misfire on two diff. cylinders.

The car sounded normal to my dad and I both, so I cleared the codes and drove away. It was after hours and the dealership was closed by this time, so I couldn't drive over there for them to have a look.

I cleared the codes, this was day before yesteday, and she hasn't had a hiccup or check engine light ever since.

My gut tells me take it in, but with no engine light on, what good would it be?

I understand the want to document it.. but what does that gain me really? Nothing; if it fails completely under warranty, they will fix it. If I am out of warranty and I did come in and document it.. they are likely to not fix it.

I'll be honest in that this post is merely more to get a feel for others knowledge on this, as I think I will probably be filing for a lemon case for this car any day now and won't care to waste my time taking it in, though I still would like to know what others are thinking and/or would do...

Thanks guys.
 

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Next time it happens find a way to get the time and date with a watch or something and take a picture if you have a camera or camera phone. Take it to the dealer and tell them to have fun. Can't reproduce the issue, can you? Oh well, here is mr. picture. You shouldn't have to keep an OBD scanner around to diagnose and clear codes on a year old vehicle.
 

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Discussion Starter · #3 ·
Next time it happens find a way to get the time and date with a watch or something and take a picture if you have a camera or camera phone. Take it to the dealer and tell them to have fun. Can't reproduce the issue, can you? Oh well, here is mr. picture. You shouldn't have to keep an OBD scanner around to diagnose and clear codes on a year old vehicle.
My baby rolled off the assembly line Dec 21st... she isn't even a year old!! hahaha

I am watching this like a hawk now and of course will be more observant the next time; hope there isn't one but you're right, you should always be prepared.
 

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My baby rolled off the assembly line Dec 21st... she isn't even a year old!! hahaha

I am watching this like a hawk now and of course will be more observant the next time; hope there isn't one but you're right, you should always be prepared.
The biggest joke of it all is the service writer saying that "We could not replicate the issue". Ok, cool. Then i ask, "Well, what would you have done if you *DID* in fact replicate the issue?". Blank stare...... :yelwacko:
 

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Discussion Starter · #5 ·
The biggest joke of it all is the service writer saying that "We could not replicate the issue". Ok, cool. Then i ask, "Well, what would you have done if you *DID* in fact replicate the issue?". Blank stare...... :yelwacko:
I guess a better question I should ask is... what could have caused this?

Anyone else experience this yet?
 
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First thing first if you get a check engine light DO NOT CLEAR CODES!!!

If you clear the codes you erase all records of the malfunction and any chances to properly diagnose it. There would be nothing that anyone could do for you at that point.

Common causes for P0300 fault codes in my experience are unmetered air, spark plug/ignition coil, and contaminated fuel.
 

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Same thing happened to my car. Dealer reprogramed something with the cams. Never did it again.
 

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Discussion Starter · #8 ·
Same thing happened to my car. Dealer reprogramed something with the cams. Never did it again.
Interesting.... I just had the tsb for the pcm flash done... I wonder if there is a newer update?
 

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What fuel were you running at the time? just curious.
 

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I had a similar problem and I had to tell my dealer to re-train the misfire monitor.

They wanted to do silly things like replace spark plugs.

So in summary, bring it in for the misfire monitor re-training procedure.
 

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I dont get up in arms over a single hiccough and assume it was bad gass or trash in the line etc. Now if it starts to repeat.....
 

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Discussion Starter · #12 ·
Thanks all; for now I am just keeping an eye open for anything.

By the way it was 76 gas 91 oct; it's all I run really.
 

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Discussion Starter · #13 ·
Just an update:

My car is in the shop currently (was damaged by the dealership while in for service) and I just got a call that they got random misfire codes on her again.

As you can see from my post above I had the PCM flashed with a newer rev. of software, yet on the phone the supervisor stated there was a newer PCM, so they flashed it.

I called the dealer back and left a message on the recorder with my concern that there is something wrong with something if we are having this many misfires....

Just looking for some opinions on this; thanks.
 

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Being intermittent, I'd have to assume it'll end up being something electrical. A base engine issue doesn't just come and go or fix itself. So, plugs, coils, injectors, or any wiring connected to them. I would also not be surprised if only one of these cylinders is acting up and confusing the PCM into setting faults for the other. That happens quite a bit to be honest. Then it becomes an ordeal on figuring out which one is actually missing.

Another possibility would be the crank sensor, wiring, or tone ring as this input is used by the PCM to check for misfiring cylinders by watching fluctuations in crankshaft speed as it goes through the firing order.


These can be a PITA to diagnose sometimes if they are really intermittent. Just like going to a doctor and having a test done when you aren't sick or acting up, most car testing won't reveal a problem either. There'll definitely be some luck in getting it to act up or parts slinging needed to fix it.
 

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mine started getting those errors right before my clutch would not engage at high rpms took it to the dealership found the clutch pressure plate in pieces. The dealership fixed everything but did not perform the crankshaft misfire relearn procedure. Took it back and had them perform the misfire relearn and everything has been ok since.
 

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Discussion Starter · #16 ·
Thanks both of you for the responses.

GrabberGT, I got 3 different codes before; random, and then two individual cylinders. I wish I knew what exact codes they just received on her to know if it was the same or not. :/

RaceRed, thanks; I will let my dealership know about your troubles and fixes to see if it can help.
 

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Thanks both of you for the responses.

GrabberGT, I got 3 different codes before; random, and then two individual cylinders. I wish I knew what exact codes they just received on her to know if it was the same or not. :/

RaceRed, thanks; I will let my dealership know about your troubles and fixes to see if it can help.
I found this on another post
21474 SOME VEHICLES COULD EXHIBIT MISFIRE CODES AFTER CERTAIN REPAIRS - MULTIPLE VEHICLE LINES
SOME VEHICLES EQUIPPED WITH ON BOARD DIAGNSTICS (OBD) MISFIRE MONITOR NEUTRAL PROFILE LEARNING CAPABILITIES MAY EXPERIENCE THE MIL ILLUMINATING ACCOMPANIED BY ONE OR MORE ENGINE MISFIRE CODES P030X IF THE CRANKSHAFT POSITION SENSOR PROFILE (MP_LRN) IS NOT RELEARNED FOLLOWING CERTAIN HARD ENGINE REPAIRS. THE MP_LRN DATA IS NO LONGER CLEARED WITH A KAM RESET OR BATTERY DISCONNECT. REPAIRS THAT REQUIRE RELEARNING THE MP_LRN DATA: CRANK SENSOR,CRANK SENSOR, TRIGGER WHEEL, ENGINE TIMING, DAMPER, CRANKSHAFT, ENGINE, FLYWHEEL/FLEXPLATE, CLUTCH (MANUAL TRANS), PRESSURE PLATE (MANUAL TRANS),TORQUE CONVERTER (AUTO TRANS). FROM THE IDS TOOLBOX SELECT "POWERTRAIN", THEN "SERVICE FUNCTIONS", THEN "MISFIRE MONITOR NEUTRAL PROFILE CORRECTION" AND FOLLOW THE PROMPTS.
EFFECTIVE DATE: 08/26/2010

21463 2010-2011 5.0L/6.2L - MISFIRE CODES P0300-P0316
SOME 2011 MUSTANG VEHICLES EQUIPPED WITH A 5.0L ENGINE AND 2010 F150 AND 2011 SUPER DUTY VEHICLES EQUIPPED WITH A 6.2L ENGINE MAY EXHIBIT THE MALFUNCTION INDICATOR LAMP ILLUMINATING ACCOMPANIED BY ONE OR MORE DIAGNOSTIC TROUBLE CODES P0300 THROUGH P0316. IT IS RECOMMENDED THAT THE CRANKSHAFT POSITION SENSOR PROFILE (MP_LRN) BE RELEARNED PRIOR TO PERFORMING THE PC/ED PINPOINT TESTS FOR THESE CODES. FROM THE IDS TOOLBOX SELECT "POWERTRAIN", THEN "SERVICE FUNCTIONS", THEN "MISFIRE MONITOR NEUTRAL PROFILE CORRECTION" AND FOLLOW THE PROMPTS. IF ONE OR MORE OF THE MISFIRE CODES RETURN AFTER PERFORMING THE RELEARN PROCEDURE, REFER TO THE PC/ED PINPOINT TESTS.
EFFECTIVE DATE: 08/17/2010
 
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Just an update:

My car is in the shop currently (was damaged by the dealership while in for service) and I just got a call that they got random misfire codes on her again.

As you can see from my post above I had the PCM flashed with a newer rev. of software, yet on the phone the supervisor stated there was a newer PCM, so they flashed it.

I called the dealer back and left a message on the recorder with my concern that there is something wrong with something if we are having this many misfires....

Just looking for some opinions on this; thanks.
Being intermittent, I'd have to assume it'll end up being something electrical. A base engine issue doesn't just come and go or fix itself. So, plugs, coils, injectors, or any wiring connected to them. I would also not be surprised if only one of these cylinders is acting up and confusing the PCM into setting faults for the other. That happens quite a bit to be honest. Then it becomes an ordeal on figuring out which one is actually missing.

Another possibility would be the crank sensor, wiring, or tone ring as this input is used by the PCM to check for misfiring cylinders by watching fluctuations in crankshaft speed as it goes through the firing order.


These can be a PITA to diagnose sometimes if they are really intermittent. Just like going to a doctor and having a test done when you aren't sick or acting up, most car testing won't reveal a problem either. There'll definitely be some luck in getting it to act up or parts slinging needed to fix it.
Thanks both of you for the responses.

GrabberGT, I got 3 different codes before; random, and then two individual cylinders. I wish I knew what exact codes they just received on her to know if it was the same or not. :/

RaceRed, thanks; I will let my dealership know about your troubles and fixes to see if it can help.
In my experience random intermittent misfire faults usually stem from control units or their software. When you start having issues with hardware such as sensors and wiring the faults become more pronounced and occur more frequently. However issues with PCM control units are damn difficult to diagnose because you can't simply plug in a new unit. They have to be irreversibly pared and programmed to the car and cannot be returned if it is not the cause of the problem.

Mercedes Warranty makes me jump through flaming hoops of fire to order and install a new PCM, or trans valvebody, or even tire pressure monitor control units. A lot of people here have had issues with Ford warranty, but just imagine what Ford techs have to go through just to diagnose problems and earn a living!

I bet you will eventually get a new PCM and crank sensor. I hope they can easily replicate the problem so the process gets done soon:bigthumbsup
 

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Discussion Starter · #19 ·
Thanks for the kind words, grimace.

And thanks, RaceRed. But, I think that those TSBs are old enough that my PCM flash I just had done is newer than that TSB.
 

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Not sure on the MB side, but it is extremely rare for the Ford ECU's to fail, especially when not on an output driver that carries an actual load. I'm not saying it can't happen, it's just not very common. The fact that you stated the car actually stuttered or hiccuped one time indicates whatever happened actually was a legit misfire, as opposed to the PCM falsely interpreting one and setting a fault. I'd expect it to set codes with no drivability issues if that were the case.
 
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