2003 Mustang GT Cylinder 4 & 7 misfire? HELP!

69_BOSS · 06-27-2009

Just recently bought a 2003 Mustang Gt. Last night I noticed it was running a little rougher than normal. Sure enough, on my way home from work the "service engine soon" light came on. So this morning I took it to Autozone and they ran a diagnostics on it and it said there is a misfire in the 4th and 7th cylinder? I'm pretty worried this is going to be something major/expensive to fix.

Any ideas, or suggestions anyone?

gilomach · 06-27-2009

these engines don't like humidity inside the spark plug holes,sounds like it needs 8 new plugs and probably one or two ignition coils.

69_BOSS · 06-27-2009

Quote:

Originally Posted by gilomach

these engines don't like humidity inside the spark plug holes,sounds like it needs 8 new plugs and probably one or two ignition coils.

So a new set of spark plugs and possibly some ignition coils should take car of it? How much do you think that'd cost me?

By the way thanks a lot for responding! Appreciate the help!

LS WAT · 06-27-2009

what codes did your car throw?

69_BOSS · 06-27-2009

Quote:

Originally Posted by LS WAT

what codes did your car throw?

I didn't see. He showed it to me and I saw Cylinder misfire in 4 and 7.

LS WAT · 06-27-2009

a bad O2 sensor will cause a misfire among other things thats why it's important to know what code is thrown, my scanner shows the code and then I have to look it up.

69_BOSS · 06-27-2009

Quote:

Originally Posted by LS WAT

a bad O2 sensor will cause a misfire among other things thats why it's important to know what code is thrown, my scanner shows the code and then I have to look it up.

Damn I wish I would have seen it.
I won't be able to have it work on till Monday.

Will driving around make it worse? Or is it ok to drive around for a few days?

69_BOSS · 06-27-2009

Bump?

Will the car be ok to drive for a few days before I get it fixed?

Guties · 06-27-2009

You should do this job yourself. Its easy. First I would pull the coil packs and make sure they are clean of moisture. Then pull the plugs and make sure they are in good working shape... replace if needed. Try that before you go run out for coil packs because they can get costly.

And don't drive it.

AJCaron12 · 06-27-2009

Quote:

Originally Posted by 69_BOSS

Just recently bought a 2003 Mustang Gt. Last night I noticed it was running a little rougher than normal. Sure enough, on my way home from work the "service engine soon" light came on. So this morning I took it to Autozone and they ran a diagnostics on it and it said there is a misfire in the 4th and 7th cylinder? I'm pretty worried this is going to be something major/expensive to fix.

Any ideas, or suggestions anyone?

I always tune up a car when I get it, regardless of the history. In your case I would replace all 8 spark plugs, go with the Ford Motorcraft factory ones. Then erase the check engine light. After that see what happens; see if it runs rough and see if the CEL comes back on. These cars are known for bad coils. If the CEL comes back on and you have the same cyl. 4 and 7 misfires. Move the coils to a different cylinder and see if the misfire moves. If it does, you know it's a coil.

69_BOSS · 06-27-2009

Quote:

Originally Posted by Guties

You should do this job yourself. Its easy. First I would pull the coil packs and make sure they are clean of moisture. Then pull the plugs and make sure they are in good working shape... replace if needed. Try that before you go run out for coil packs because they can get costly.

And don't drive it.

Hmmm, I don't know if I should.... I'm afraid I'd screw something up.

Damn, they won't look at the car until Monday and I need it to get around....

Guess I'll just have to stay home this week end.

69_BOSS · 06-27-2009

Quote:

Originally Posted by AJCaron12

I always tune up a car when I get it, regardless of the history. In your case I would replace all 8 spark plugs, go with the Ford Motorcraft factory ones. Then erase the check engine light. After that see what happens; see if it runs rough and see if the CEL comes back on. These cars are known for bad coils. If the CEL comes back on and you have the same cyl. 4 and 7 misfires. Move the coils to a different cylinder and see if the misfire moves. If it does, you know it's a coil.

The thing is, through the dealer I bought the car through I got a warranty. I'm afraid if I take it anywhere and get it checked/worked on it'll void the warranty. So I'm going to have to wait until Monday to find out what I'm going to do about it.

AJCaron12 · 06-27-2009

Quote:

Originally Posted by 69_BOSS

The thing is, through the dealer I bought the car through I got a warranty. I'm afraid if I take it anywhere and get it checked/worked on it'll void the warranty. So I'm going to have to wait until Monday to find out what I'm going to do about it.

Um...you forgot to mention before that you had a warranty at the dealership. If that is the case take it to the dealership and they will fix it for free. No brainer.

69_BOSS · 06-27-2009

Quote:

Originally Posted by AJCaron12

Um...you forgot to mention before that you had a warranty at the dealership. If that is the case take it to the dealership and they will fix it for free. No brainer.

But it's not a Ford warranty. It's a small time car lot. And its a supplemental warranty, one of the ones thats covered by a company, not the dealership. The thing is I have to wait until Monday to find out what their going to do about it.

Do you think it will be ok to drive until then?

LS WAT · 06-27-2009

Quote:

Originally Posted by 69_BOSS

Do you think it will be ok to drive until then?

drive it, I would, the worst that will happen as it seems is terrible gas milage but I wouldn't take no trip in it but around town, to the store ect Mine was doing the same and I drove it for a week with it jerking, very annoying and ended up being the O2 sensor with a 1131 code.