Misfire

mightymike

I have an 03' Mustang GT and I have had a misfire on Cylinder 4 according to the computer code from the dealer. It happens when I get on it, and at a high RPM it will all of a sudden chug, and when I let off the gas it seems to return to normal. The problem has occurred three times and the service engine soon light comes on. The dealer can not seem to fix the problem. Has anyone else had this problem?? Also, is this misfire doing damage to the engine?

Mr_Shiftright

Really? The dealer cannot fix a cylinder misfire even after the computer has identified which one?

Excuse me, please, no offense, but that is really pathetic performance from your dealer.

Okay, let's back up. What DID he do for your car?

New plug wires or plugs or what, other than to reset the light?

We'd need to know what was tried before suggesting anything.

alcan

Any chance the engine's been pegged against the rev limiter?

vidtech

i am assuming you have the v8.i have seen many of the individual coil packs fail which sit directly on the spark plug.the engine i have seen these failures on is the 4.6 liter.

mightymike

Mr. Shiftright,

Thanks for your reply. I am frustrated myself. Part of my problem is I do not know much about cars so I am not a good advocate for myself when I am at the dealer. I can not problem solve with them and I do not have the first clue about what they should be doing!! Therefore I am here trying to arm myself with some information so next time I go back, I am better equipped to make sure they fix it right.
The fist time on 7-18-03 they fixed the coil and assembly on cylinder 4, they said it was bad and cause the misfire. On 7-28-03 they said that Ford had put a new program out on a buletain board because other people were having this problem and they re programed the computer, (PCM Calib level), I have no idea what that means, that is what it says on my repair ticket. This last time, I brought the car to my local Mustang shop and they ran the computer and the code ( I saw it myself) said misfire on Cylinder 4 again, so I brought it to the dealer and they ran the codes and it must have reset at the mustang shop because the code they got at the dealer, at least what they told me, was they only got the crankshaft sensor failure code. They informed me that this may have caused the misfire. So, I left thinking it was only a matter of time before this light comes on again.
I do not know what the rev limiter is, however, I can gues that when you hit redline, it triggers something, perhaps that is what happened to me the other day and not a misfire? How would one know the difference between a misfire and rev limiter kicking in?
The light has not come on, however, I suspect it is only a matter of time. When the light does come on and I go back to the dealer, what would you suggest?
Thanks again!!
Mike

mightymike

Hello alcan,
I have redlined the car before and now that I think about it, I think I can tell the difference between the two. The misfire is a more severe drop in power and as the rpm's start to scream all of a sudden it seems as if the car is going to just stall and a chug sound as if the car was gasping for air to stay alive, the rev limiter is a lot less dramatic. I am not certain, but I do not think that this was the rev limiter. Based on the info above, what do you think?

mightymike

Vidtech, by the way it is a v8 an yes if you read the post I just wrote, you are correct about the coil!!
Oh yeah, I also meant to tell you guys that I have a few mods on the car, however, my dealer does not think they are related to the misfire. I have a Basani X pipe, Ford racing gears 3:73, a cold air induction kit and steeda pulleys. Since I have a few mods, I have to go to the one dealer who will overlook them and not black ball me from having work done under the warranty. The dealer happens to be a 50 minute drive. At least they will work with me!!

Mr_Shiftright

Have you tried to induce this misfire by loading the engine, that is, running up a slight incline in too high a gear, like 5th?

If this misfire only occurs at high revs, it very well could be the limiter--which does tend to be dramatic, if I recall correctly (I try never to redline borrowed cars).

mightymike

Hey Joe,
Thanks again for your thoughts on this matter. I have not tried to induce the misfire, however I will try to do as you suggested. Any other advice? Is the misfire going to damage the engine or other parts. If the problem does re occur, and the light goes on, what would you suggest?

Mr_Shiftright

Well a persistant misfire could theoretically damage the catalytic converter.

If it re-occurs, and the previous repairs did not fix it, then obviously the problem is "further downstream" in the diagnostic chain.

Often, especially with today's complex cars, mechanics fix the symptom but not the primary cause. This is why it comes back time after time.

terran420

I have a 87 mustang gt with the 5.o Ho the other day I had to get on the gas and was at about 45 or 50 mph when low coolant light and low washer light came on the car had a massive hiccup is the best way to say what happen my alltanatior dropped to almost zero all lites dimed heard alot of relays coming on lost all power car died the two warning light have been comeing on at like 5 min inter car runs fine untill warning lights come on almost dies ever time checked all fulieds in car everything was fine if anyone knows were I should start on car to find problem please help code reader says all good please any info would help (stumped in Texas)

terran420

i timed warning lights with stop watch low coolant and low washer come on at ten sec inter evertime, promblem also happens when only key is turned on with or with out engine running the problem is getting worse by the day please help someone im on a limited buget i cant aford to wast time fixing the wrong thing all i know is something is pulling a draw ever ten sec and its so much it sometimes kills the engine. Please help... (stumped in texas)

desi501

I believe Vidtech is on the right track. I have fixed many 4.6 with the same problem. What your going to have to do is swap that coil with another cylinder and then reset the code. When it sets the code again, check to see if it is the other cylinder now. If the miss moved with the coil, there is your problem. If it didn't, start looking at a fuel injector.

rottmom

I have an 02 GT that has the same problem. The first dealer said that the misfire was in 3 or 4 then reset the codes and refused to do anything else if the light came back on unless the car was returned to stock. Of course the light came back on and I located another dealer who replaced two coils. They said that the misfire was on 3 and 5. I drove the car home (25+ miles) and the light came back on 2 miles from my house. I have a BBK cold air unit and recently had underdrive pulleys installed. I have had an intermitent stalling problem with this car since I have it. The engine will immediatly stall and then will refuse to start for a period of time. Other than the light the engine appears to run fine. I have noticed that both times the light came on I was in a high rev..

desi501

I would think you'd be able to feel the miss in a GT although you never said what engine you have. Your just going to have to get the codes read somehow or you'll have no idea at all whats happening. Once you know what the code is, it will be a little easier to guess the problem. It may not be a miss this time.

rottmom

I have a 4.6. The problem is definitely a misfire according to the codes each time that the dealer has read them. It is going back agin tomorrow.

desi501

Assuming you have a "coil on plug" engine, just the the coil from the cylinder that's giving the code and swap it with another easy one from up front. If the code moves with the coil, then it's the coil, if not look at the plug or the injector.