Need some help with my mustang!! Please pm me! Thanks a billion.

Why not post the question here? maybe somebody can chime in on some advice.

Your right. Ok so i purchased a 96 mustang 3.8L convertible, no didnt need cobra or gt. just a lil something to keep from putting to many miles on the jag. So i kept getting a p0304 code ( cylinder 4) misfire. Since i bought car used i changed spark plugs, wires, coil pack, pcv valve and air filter. I keep getting the code. All of the cylinder are firing wen i do a spark test. Is it possible the #4 fuel injector is bad? If it is, ill just replace all six to avoid it in the future

Have tried to clear the code and see if it comes back? I know it should have went away after so many restarts but not sure how long ago you made the latest change? If you don't have a OBDII scanner and are up at the OBRPC or if you are going to Shongum this weekend, find me, I keep one in my car and can clear the code for you.

All the mechanics must have gone to sleep so they can get up and work on all the dead Fords sitting in their lots. As hd said I assume you have cleared the codes right? There are several steps you can take, if you have cleared the codes that is, you can switch a fuel injector and see if the code follows it or not. There is a TSB for that car which is 97-8-6. I could go on but some information is needed. Mike

Former Ford mechanic here.

 

Not too much can cause a P0304. You already did the ignition side of things. Next thing to do is what Missionmtman says, and swap cylinder 4's injector with another one. If the code follows the injector, there's your problem. If not, break out the compression tester and prepare for things to get ugly.

 

The Ford 3.8 engines had headgasket issues in earlier versions, but not on the Mustangs. Cylinder 4 is the driver's side front most cylinder, as I'm sure you are aware. Very accessible.

Have tried to clear the code and see if it comes back? I know it should have went away after so many restarts but not sure how long ago you made the latest change? If you don't have a OBDII scanner and are up at the OBRPC or if you are going to Shongum this weekend, find me, I keep one in my car and can clear the code for you.

Yup i keep obdII in car as well. Ill try swaping out fuel injectors todays and i hope thats what it is so its an easy fix. Thanks

Former Ford mechanic here.

 

Not too much can cause a P0304. You already did the ignition side of things. Next thing to do is what Missionmtman says, and swap cylinder 4's injector with another one. If the code follows the injector, there's your problem. If not, break out the compression tester and prepare for things to get ugly.

 

The Ford 3.8 engines had headgasket issues in earlier versions, but not on the Mustangs. Cylinder 4 is the driver's side front most cylinder, as I'm sure you are aware. Very accessible.

Gunna swap out these injectors today and see wat happens

Former Ford mechanic here.

 

Not too much can cause a P0304. You already did the ignition side of things. Next thing to do is what Missionmtman says, and swap cylinder 4's injector with another one. If the code follows the injector, there's your problem. If not, break out the compression tester and prepare for things to get ugly.

 

The Ford 3.8 engines had headgasket issues in earlier versions, but not on the Mustangs. Cylinder 4 is the driver's side front most cylinder, as I'm sure you are aware. Very accessible.

 

What he said.

I kept getting a mis-fire code in my mini van about a month after new plugs. Drove me nuts checking wires, coil pak etc and was about to do the injecter swap but just for the heck of it and because it is so much easier i moved the plugs around and sure enough one was defective, replaced it and that was that.

I kept getting a mis-fire code in my mini van about a month after new plugs. Drove me nuts checking wires, coil pak etc and was about to do the injecter swap but just for the heck of it and because it is so much easier i moved the plugs around and sure enough one was defective, replaced it and that was that.

 

This is also a good point to make, I cant tell you how many hours i've spent troubleshooting engine issues only to realize cheap plugs ( or plugs the engine didnt like ) were the culprit.

I agree on that point about the plugs etc. Assume you are using a Platnum or double platnum plug? I have to keep telling myself think simple first. If the light does not work first see if the lamp is plugged in not take it all apart to find out it was unplugged. Lol

Compression test..

This is also a good point to make, I cant tell you how many hours i've spent troubleshooting engine issues only to realize cheap plugs ( or plugs the engine didnt like ) were the culprit.

 

That is a not uncommon issue. Sparkplug boxes get thrown around in parts stores, sometimes the porcelain gets a crack in it, inducing a slight misfire.

 

I had a comeback on a tuneup job that had this as the culprit. Either the plug was defective, or I dropped one on the concrete floor when installing the plugs. Shit happens.

I agree on that point about the plugs etc. Assume you are using a Platnum or double platnum plug? I have to keep telling myself think simple first. If the light does not work first see if the lamp is plugged in not take it all apart to find out it was unplugged. Lol

Using dbl platinum

Cheapo copper plugs are your friend.

 

Also, if your injector is bad, they are easy to rebuild. Unless the thing wont fire at all, in which case you need a new one.

I have had this happen before , if all else fails and you have tried every good suggestion posted here ------ that coil is pulsed by the computer , the spark might "look " ok but it might be weak . The pulse width might not be long enough to give a hot spark . But like someone said before you must clear the codes , some fords will shut down a cylinder for a missfire untill it is reset . --- ASE master tech 25+ years PM me if you want to talk it over .

Ok gentlemen, so far its been a few days since i replaced coil pack. The stang hasnt thrown any codes at me. Drove about 200 miles since fix; lets hope that the coil pack was the main issue. Thanks for the suggestions, greatly appreciated!

Thank You for the update !

My coil-packs in ALL my 4.9L Ford CVPI's (92,96,00) all had coil-pack woes.. I did them 1 at a time (as they went) as the $400 or so for all 8 would be $$. I would notice a rough idle and listen for other noises.. (sounds like BAD GAS running.. fwiw)..

 

sounds like you got it fixed.. never had a replacement one go.. but for the cheapy $50 'copies' you never know..