Bret Henninger

Hello, I have a 2003 ford mustang with 75k miles, automatic.

I just bought the car a little over a month ago from a ford dealership.

1 Week after purchasing the mustang I was having misfiring/studding at low acceleration between 25-50mph. I brought it back to the dealership and they advised me I had 3 weak coil ignitions. They were replaced with OEM motorcraft and all new spark plus.

2 days later the problem was still their. I brought it back to the dealership and another coil ignition was replaced. They said the rest of the 4 needed to be replaced for the problem to be cleared because the ECU was reading the old coil ignitions as weaker then the new ones. I picked up OEM ignition coils from a local hardware store and replaced them myself.

Problem still exist. I cleaned the throttle body and MAF sensor. I order a SR cold intake from American Muscle and will install it was I receive it. Just need some guidance on where to look next. Please help! My first mustang and it hasnt been fun!

AMAlexLazarus

OP-Sorry to hear about the trouble you're having here! What kind of coils were picked up locally? I can see that you had said they were OEM but do you have a model number so we can help get a better idea of what's going on? If anything I might swing by the dealer one last time to let them know what you had swapped and to see if they can establish what could be causing the trouble!

-Alex

Bret Henninger

Alex, thanks for the quick reply. I picked up Motorcraft Original Equipment (O.E.) Ignition Coil at Advance Auto. Specs below.

Peak Current: 8.5
Voltage: 35000
Primary Voltage: 14.2
Brand: Motorcraft
Maximum Voltage: 35000
Primary Ohm Resistance: 0.5
Secondary Ohm Resistance: 5500
Coil Color: Black

I have heard from another source that it could be the ECU? Not sure if this would be the case here, thought I would throw it out there.

AMAlexLazarus

Bret,

Very welcome . That's definitely on the interesting side. If anything I would recommend maybe getting a second opinion. It can be incredibly difficult to pinpoint something like this behind a computer!! Sorry I'm little help on this but we'll bump it up to see if we can get another opinion!