Just got my truck back from the dealership. STILL Have a blinking check engine light but only sometimes when I really put my foot in it. When I let off it blinks for a few seconds and goes off. So frustrated

 

You have a mis-fire condition...

 

coil pack?

 

check for codes that will direct you to the cyl that misfired. you will probably have multiple cyl misfire and at least two others identifying the cyl that misfired. this does not mean the check engine light is on, these codes are stored as pending.

 

^^^ yep ^^^

 

Good advice. If this dealership can't figure it out, take it elsewhere.

 

So the codes should be stored? I have an obd2.scan tool I'm going to try and use at the local parts house. If it is a misfire, is there an easy way to isolate the problem? No loss of power and same mpg is what gets me

 

P0300 random misfire. Dealership said it was cylinder three.

 

you should have at least one more code stored, po300=multiple misfire/random
dealer came up with po303 for cyl 3 but again should have been at least one other to justify the po300. the issue can be anything from a bad coilpack to just a spark plug with a gap thats too wide or simply tired spark plugs. how old are the plugs,switch coilpack location etc depending on plug age/mileage just replace them all before you go with coilpack......

 

My truck was doing the same thing. F150 3.5 Ecoboost. The light would blink at hard acceleration with a little loss of power then let off gas and blinking stopped. Did this a few times then light came on permanently. When I checked it was cylinder 1 misfire. I had all coil packs, wires, and plugs replaced at dealer, then they replaced high pressure fuel pump because it wasn't pushing enough psi and gave it back. Four days later again the light would blink then go off at hard acceleration then stay on again. The computer said it was a misfire for cylinder 1 again. I now have it at the Ford dealership trying to figure it out. Very frustrated. Anyone else have this issue but got it fixed?