Intermittent Flashing Service Engine Soon Light 02 Gt

Flashing means a misfire is occurring. You may have one or more P030x (x=0..8) codes stored. P0300 is a random/multiple misfire code while P0301..P0308 point to specific cylinders.

You might start by pulling the coils and checking down in the plug wells for oil (sometimes valve cover gaskets can leak and the oil can pool down in the plug wells.)

That would be cylinder 8.

I just went through this with my GT not too long ago. It was showing a misfire on 4 and 8. I replaced the COPs and all is well.

For me, the misfire would occur after the car had been sitting for more than a day in colder temps (below 40) or after it had rained. If I kept driving it regularly (every day), it would not misfire.

Redbuffalo95 said:

I'm trying to work on it right now but I'm new to this so where is cylinder 8 located and how do I take out the plug and coil?

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If you haven't figured it out already (I think you may have judging by the post after this from you), cylinder 8 is at the back of the block, closest to the firewall. It's on the driver's side of the engine.

Taking the coil out is easy...unplug the connector from the COP, and you just need a 7 mm (I think) socket to undo the one bolt holding it in place. Once that bolt is out, just pull the COP out. You might need to rotate it out of the plug well as you remove it just for clearance. The boot is made of rubber though so it shouldn't matter.

Given the symptoms you've stated, I can't, no. But I had the intake manifold crack a few years ago and coolant sprayed all over the place under the hood. So with that said, definitely get it tested by a reputable shop to determine where the leak is coming from and go from there.

My guess would be a cracked intake manifold crossover.

I JUST finished repairing TWO 4.6 Romeo intake coolant leaks.

One was so big that it hydro-locked the #1 cylinder. Locked the motor up so tight it couldn't be turned over by hand. I was lucky that the motor wasn't damaged.

The 2nd was a slow leak from the coolant crossover and the heater nipple area. This caused coolant to be in #1, #4, #5, and #6. There was coolant in the valley obviously from the T-stat housing area.

I can promise that these Ford 4.6 intake manifolds CAN leak from way more places than a cracked coolant cross over. The good news is that many are "repairable" with new gaskets and surface cleaning.

Look closely at the design of the cylinder heads. It's easy to see a way that a coolant leaking from the intake manifold can run along the heads and fill the spark plugs holes of an entire side.

Bottom line is the Modular 4.6 intake manifold is easily damaged when over heated. Just having a metal cross over does not stop the intake from being damaged by over heating.

I really can't understand the RUSH to jump to a bad head gasket BEFORE the other and frankly more common causes have been ruled out. Instead of guessing why not do some more testing? I promise you that IF the motor is cleaned up and the spark plug wells are fully dried out, it won't be that hard to see where it's leaking from (if it's leaking from an intake gasket). Do you really want to pay a professional to clean your motor to find a leak?

Further. In the event that no coolant is found on top of the cylinder heads, then that is useful information as well. As in it must be leaking from somewhere else.

Finally. Consider that IF coolant is allowed to stand inside the spark plug wells this can and does damage the COP boot insulator. Which means that sometimes just drying out the spark plug well isn't enough to stop a misfire.

If a blown head gasket is strongly suspected, then go straight to the compression test. However just remember that normally there are other symptoms associated with a blown head gasket. Water in the oil? Oil in the coolant? Running like crap? Miss fires on multiple cylinders next to each other?

EDIT: thinking about it and I can't honestly think of a way that it's even possible for coolant to get into the spark plug wells from a head gasket leak. Just think about how the cylinders are designed and the path the coolant would have to take to get into the spark plug wells from the head gaskets (short of a out right crack).

Redbuffalo95 said:

Do you know any other reason outside of a head gasket being blown that there would be coolant on top of the plugs?

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I had same issue and just needed intake manifold bolts retorqued. I had the Ford Performance one installed about a year ago...probably wouldnt have happened if I chose all aluminum one. But all is well now and I changed plugs and coils too. (dg508 motorcraft plugs are on amazon for best price possible).