DEADEYE7

I have a 2003 v6 which started missing under load or when I rev car in neutral above 3000 rpms it starts cutting out. It has 105000 miles. It threw codes P0316 and P0301. I pulled plug on cylinder 1, and it was light tan and gaped about .060. Looked for obvious vacuum leaks , etc. Not sure where to begin to troubleshoot without throwing money at parts with all the different sensors. Last mustang I had was a 87 gt, which was easy to work on. Any ideas on where to start first? How do I check the coil pack? My guess is there first.

petrock

I'd start with the plugs & wires first. The vibration from the high RPM's may be wiggling something lose. Another thing to try is to drive the car to a dark & ventilated location and pop the hood. Then reproduce the problem while a buddy looks into the engine bay. Look all over the engine for any flashes of light (a.k.a. sparks). Something may be shorting and causing the misfire. If there is a spark, it will be fairly small and may or may not make a clicking noise. So the less ambient light you have around you the better.

If your handy with a multi-meter, you can contact your local AutoZone. They have a spec sheet for our coil packs which has the resistance levels for the primary & secondary coils that you can test yourself.

Good luck...

lilpanther

I was having this issue last year and it ended up being my Cam shaft Synchronizer. I replaced the spark plugs, spark plug wires, coil pack, and the fuel filter and we finally figured out the cam shaft synchronizer was the culprit. And mine only had 55,000 miles on it when all of this happened.

mustangmike09

coil pack is oen of the most common failures on these cars

petrock

It is also one of the most commonly misdiagnosed parts on these cars. Alot of people waste their time & money throwing parts at a problem instead of properly diagnosing it first, and the coil pack is one of the "go to" parts to replace when there is an ignition problem resulting in alot of perfectly good coil packs in the trash heap. Just sayin'...

mustangmike09

Your right, but common sense tells someone to check other things first. But I do realise that is a rare trait these days. Mine just went out a couple months ago around 55k miles on the car.

I pulled my 6 month old spark plugs and they looked fine. So after reading and researching and using some common sense/knowledge, I bought a new set of wires and a new coil pack. I first put on the wires to test problem. No change. Then I changed to the new coil pack. Problem fixed. So I took the wires and cleaned the couple of grease spots off and took them back w/ no problems at all.
So in the end, I went through all of my steps and only spent money on a coil pack which is exactly what My problem is.


But **** if your having a missfire like problem, check your damn plugs first. Thats common sense.....

llcccc

I have mustang 2003 just bough two weeks ago have the same problem It run very good at idle but running extremely rough while accelerating (at 300 rpm) I allready replaced 6 plugs and plugs wire but still have same problem what Ideal you will have for me

Thanks alot

varnco

Check your coil pack with an ohm meter.

Check the connections from the power connection across the other 3 connections. The ohms across all 3 should be very similar. If one is off, it could be a bad coil pack.

You could also do the same to check them across cylinders on the coil pack. They should all have about the same resistance.

jfk1966

My 2002 Mustang convertible had misfire underload, checked the fuel injector with a noid light, checked the plug and wire, all were good. Had some spark with vehicle not under load - changed out the coil pack for about $60 - took less than 5 minutes - and the entire issue was resolved. Car runs like a champ now.

ryanam4793

I would bet on a bad ignition coil. Exact same problem I had. Easy fix can do it yourself in less than 30 mins.