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Hey this is my first post to the forum to I hope i am in the right place. I have a 2008 mustang GT 4.6 with only intake and exhaust mods that occasionally the CEL flashes for up to 5-20 seconds of which during that time I experience severe power loss. Once the light goes off the car runs fine. I did some research and found that a flashing CEL means the mustang's computer has detected at least one or more misfires on the cylinders. I just took it to the dealer today because they told me this was a problem that needed to be solved ASAP because it could cause serious engine problems. However, after spending almost $100 running my ford dealerships retarded diagnostics (because i thought warranty would be covering this malfunction) they told me they couldn't find any problems with my car at all and that its in great running condition. So, here's my main question if there is anyone out there who can help. Since I can't produce my car experiencing the problems to the dealership when it is actually screwing up, how do I figure out what's going on with my car since this is still an occasional problem? My fear is I am going to screw up a lot more parts continuing to run my car in the condition it is in but I don't even know where to start when so many things can cause an engine to misfire. The only things I could think of is the fact I am 4,000 miles overdue for a fuel filter change which will be taken care of soon. Has anyone experienced this problem before and if so were you able to find a resolution? I am open to any and all suggestions all help is greatly appreciated. Thank you.
 

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A flashing CEL normally indicates a misfire. A bad plug or coil pak are the 2 most likely causes. But the cylinder # of the culprit cannot be easily determined without any codes. And changing all of the plugs and cp's will be expensive, especially if it has to be done by a mechanic.

Suggest replacing the fuel filter first, and proceed from there.
 

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Thanks for the reply, that's what I was thinking of doing. Already went and got a fuel filter so I'll take care of that an hopefully that will do the trick. The flashing CEL happens not very often at all and if the fuel filter doesn't fix the issue how expensive are we talking about if I'm gonna have to start changing cp's and plugs? I don't wanna drive it with bad parts for so long I cause other failures, so this might be just a process of elimination, likely not gonna be good on the wallet... Also, long as I get motorcraft parts I can get them likely put on myself and not worry about warranty issues, unless there is some major difficulty to doing so on my mustang. Ive changed plugs an wires on vehicles with distributors but not on one of my design. Is it a bad idea to do it myself? Thanks again.
 

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You're welcome.

Hopefully, your 08 GT has heads and spark plugs that are different from those in the 05's, 06's, and I believe some of the earlier 07's. The plugs in those GT's can be a bear to replace. They have a 2 piece design, and carbon tends to build up in the annular area between the ID of the smooth, unthreaded section of the plug orifice in the head and the OD of the plug, which can "weld" the lower section of the plug to the head and cause it to break off and remain in the head during removal. A special tool is then needed to remove the piece left behind.
There's a TSB that describes how to minimize the chance of breakage when replacing the plugs. Numerous GT owners have successfully replaced them by following the TSB's recommendations. One item it does not mention, however, is having a lot of patience, and a very steady hand, especially if the car has accumulated a lot of miles.
You can gets prices for the plugs online. I believe a set costs around $100- $150. Also, I think one piece designs are available from Champion. An independent shop will probably charge a few hundred $ to replace the plugs. And as I'm sure you already know, a dealership will normally charge more than a shop.
I'm not sure how much the coil paks are. Perhaps someone else can chime in.
 
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Hey this is my first post to the forum to I hope i am in the right place. I have a 2008 mustang GT 4.6 with only intake and exhaust mods that occasionally the CEL flashes for up to 5-20 seconds of which during that time I experience severe power loss. Once the light goes off the car runs fine. I did some research and found that a flashing CEL means the mustang's computer has detected at least one or more misfires on the cylinders. I just took it to the dealer today because they told me this was a problem that needed to be solved ASAP because it could cause serious engine problems. However, after spending almost $100 running my ford dealerships retarded diagnostics (because i thought warranty would be covering this malfunction) they told me they couldn't find any problems with my car at all and that its in great running condition.
Hi mustangmax420,

Welcome to the forum! I can escalate this for you. Please PM me with your VIN, dealer, mileage, and contact info so I can help.

Deysha
 

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I had the same exact problem with a defective plug after I had just replaced the motorcrafts with one piece champions. It was usually worst when the car was cold, so I plugged a code scanner in when I knew it would do it. While the light is flashing it will say what cylinder is missfiring, but it doesn't store that information for some reason. I think you're going to have to catch it youself with a code scanner and see where your problem is.
 

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An intermttient problem is always hard to diagnose. What about a COP tester?


Sent from my Autoguide iPad app
 

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I dono why ford couldnt find a code. on my car (06 GT) it had a missfire flashing light then it went away. and when i got hoem i pulled out my reader (let it be known there was no check engine light still on at this time) and looked under pending codes and sure as s#!t there was an error code for missfire cyl #3. so either i have a better code reader than ford (doubt that) of your shop is full of idiots.
 

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I've had a similar intermittent code issue. Sometimes I would get the random misfire code and sometimes a flashing light with no code. Sometimes the CEL would stay on, but no code would be stored.

I pulled and replaced the plugs and have had no problems all week, until today. I got a P0352 --ignition coil b issue.
 
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