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George H.
George H., ASE Certified Technician
Category: Ford
Satisfied Customers: 18394
Experience:  ASE Master Tech 15+ Years
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Mustang gt: I have a 2008 Mustang gt 4.6 I drove it about

Customer Question

Hi I have a 2008 Mustang gt 4.6 I drove it about 35 miles to a friends house to change the spark plugs it ran perfect just a little sput around 2,000 rpm and that's all. So I changed the spark plugs and clean all ignition coils with electrical cleaner and put it all back together and then it idled really bad and I smelt fuel that wasn't being burnt off and ended up getting these codes. p0351,p0352,p0353,p0354,p0355,p0356,p0357, p0358.
Submitted: 7 months ago.
Category: Ford
Expert:  George H. replied 7 months ago.
Hello I will help you with your question, Did you spray the electrical cleaner in the connection to the wire harness or up in the boot where the spark plug is?
Customer: replied 7 months ago.
I sprayed up in the boot where the spark plug goes, also I sprayed where the harness connects to the coil on the coil I never sprayed the connectors on the harness itself
Customer: replied 7 months ago.
I'm not sure if the cleaner ruined them or not
Expert:  George H. replied 7 months ago.
Once you sprayed how long until you reassembled them?
Customer: replied 7 months ago.
About an hour then put it all together drove for a little ran kinda bad so went back re did it all and cleaned coils and ran so bad I couldn't drive it so I used my friends car and came back a couple days later and tried to start and it fired up but backfired, spitted, and sputtered and if I leave it at idle it eventually dies.
Expert:  George H. replied 7 months ago.
When you "recleaned" them you sprayed more? How long to assembly after that? What exactly is the brand of the cleaner you used? The computer will shut off cylinders if the ignition is misfiring so as more miss it turns them off until it dies.
Customer: replied 7 months ago.
I used CRC Electronic cleaner and about 15-20 then I sprayed some air in the boot to see if any cleaner came out and some kinda of fluid would come out don't know if it was cleaner or what I figured it would of been dry by then. Also when I started it, it will run for a second then I push on the gas peddle and the rpms eventually go up then it pops and stutters and then I let off back to idle then it will die eventually
Customer: replied 7 months ago.
But on idle it veries sometimes it dies and sometimes it idles like crap for awhile
Expert:  George H. replied 7 months ago.
If you thoroughly dried them then my next question is what spark plugs were installed? Brand and part number please. You do clear the codes before you try to run it?
Customer: replied 7 months ago.
I disconnected the battery when I did everything and then connected it back drove it and then a code came on. No I never cleared the codes before I tried the second time and I replaced the plug MOTORCRAFT OEM SPARK PLUGS don't know the part number.
Expert:  George H. replied 7 months ago.
Ok, the plugs should be right then, sometimes people try the gimmick plugs with these results. The way this system works is the computer senses a misfire and shuts off fuel to that cylinder to protect the catalytic converter. Clearing the codes allows that cylinder to fire again. There is a problem where if the coils are shorted it will damage the computer so the cure is to check the porcelain of the plugs for carbon tracking and replace all the coils along with the computer to get back to square one. If a bad coil is still there and the computer gets replaced the new computer is damaged. I don't know if you are to that point yet, it is the worst case.\ Start by pulling the coils and blowing out any moisture from the boots, pull the plugs and inspect them. Reassemble and clear codes then start it and see. Did you do any other work than the plugs and clean the coils?
Customer: replied 7 months ago.
Well if it was wired or computer why would it happen when I change plugs cause it ran fine until I did the spark plug change and cleaned the coil so how would it do that
Expert:  George H. replied 7 months ago.
I am thinking there is enough "cleaner" left in the boots or it coated the boots and is shorting the spark to ground. If the spark feeds back through the coil to the computer that is how it gets damaged. I am focusing on the boots /coils and plugs because that is what was changed and why I asked if any other work was done at the same time.
Customer: replied 7 months ago.
No I haven't done any other work to it during that time all I didn't was the plugs and clean the coils. If I disconnect the battery will that reset everything.
Expert:  George H. replied 7 months ago.
How did you read the codes? It should have a function to clear them. Modern computers don't do well disconnecting the battery and you lose a lot of other learned info doing it that way.
Customer: replied 7 months ago.
I rented A code reader from Autozone
Customer: replied 7 months ago.
Also if the cylinder cuts off from a misfire and it eventually dies wouldn't it not start if I tried again
Expert:  George H. replied 7 months ago.
That would be better than disconnecting the battery if it has a clear function. You can also use it to check to see if the codes set again. I would do the work, clear codes and start it up. At the first sign of misfire turn it off and check the codes to see if they reset and which ones come in first. It will restart even if the cylinder was turned off, the computer is always checking for misfire and has to take action in a flash to keep raw fuel from entering the cat as they can melt in seconds.