[DomesticCars]

About a month ago I bought an '01 Mustang with 78k on it. Good shape minus some (what I thought to be) easy fixes for a moderately car-savvy person such as myself. Convertible top needs hydraulic fluid, the aftermarket hood needs to be aligned, tires, etc.

Basically the guy before me did zero maintenance, so when I bought it there were EGR codes, system lean codes, and a consistent p306 code coming up (cylinder misfire in #6.)

After testing the coil pack, indeed cylinder 6 was not firing, so I replaced the coil pack and all cylinders tested fine with a fine jump distance. Ran better, but not perfect. After about 10 miles it returned back to its normal rough idle and poor acceleration. Still getting all the same codes too.

I replaced the EGR valve and DFPE sensor, again ran a little better but didn't stay like it. Still pulling a p306 code! Still a rough idle that fluxes between 600 and 1100, poor acceleration and still seriously lacking power.

I was thinking it could be an exhaust leak after the engine block causing poor vacuum, but then why is there only a misfire on one cylinder rather than affecting all 6?

Anyone experience anything like this? I don't know if one has anything to do with the other, but my Airbag light flashes and then stays on almost every time I drive it. Between the on/off Airbag Light and CEL light staying on and flashing at each misfire... I have a free light show at night :bigthumbsup Some Pink Floyd on the stereo and I'm all set!

Any help would be much appreciated. I have some time off for the holidays and would love to pass my inspection next month!

 

[cpriest21]

Did you also check plugs and wires? Might have carbon buildup from any leaks into cylinders

 

[MasterX]

check to make sure dummshuck previous owner put the spark plug wires in all the correct places, refer to the manual if you have it, else lookup the pattern and check it, left un-corrected too long, that can kill the engine to a point.

I would expect misfire codes in 2 cylinders if that was the case, but you never know, perhaps the computer cant tell.....

Have you changed the spark plug wires? One of them could be pinched, or have a small tear/break in the silicone coating and be shorting to the headers or block or something else, hence a single cylinder misfire, or lack of fire....

 

[DomesticCars]

Previous Owner

check to make sure dummshuck previous owner put the spark plug wires in all the correct places, refer to the manual if you have it, else lookup the pattern and check it, left un-corrected too long, that can kill the engine to a point.

I would expect misfire codes in 2 cylinders if that was the case, but you never know, perhaps the computer cant tell.....

Have you changed the spark plug wires? One of them could be pinched, or have a small tear/break in the silicone coating and be shorting to the headers or block or something else, hence a single cylinder misfire, or lack of fire....

I'm in agreement with this... I'll be checking it out tomorrow and let you know what I find. Thanks for your replies and happy holidays!:shiny:

 

[Markstang]

you may want to have a compression test carried out on all cylinders and compare the pressures. this will tell you if you have some base engine problem.

 

[StalkerStang]

There is also an injector that is involved with combustion, ever look at that?

Move the injector to a different cylinder, see if the mis follows it.

 

[wmburns]

+1 on the above advice including the compression test.

Not a bad idea to CONFIRM the spark plug routing on coil pack applications. Were all factory stand offs and looms used? How about factory routing? Are the plug wires touching any metal parts? Any white spots on the plug wires?

When injector problems are suspected, consider an injector cleaning/flow test service such as InjectorRX.com. Once cleaned and tested, the injectors are as good as new.

Another option is to buy one new injector and swap into the misfiring cylinder.

In addition, consider using a "noid" style test light to confirm a COP and injector "pulse".

When multiple DTC codes are called out, ALWAYS focus first on the misfire DTC codes. Often the other codes will go away once the reason for the misfire has been resolved.

 

[cuda2000]

I have the same problem on my 1997 mustang v6, rough idle, shakes the whole car when the car is warmed up. Prior to warm up it is fine. Please post your fix when you have it! Thanks!

 

[DomesticCars]

Happy New Year everyone! Finally got a nice day and a day off at the same time, and got some work done.

I changed all the ignition cables with a Bosch wireset, and the sparkplugs with all new double platinum plugs. #6 was definitely fouled and gunky, and starting it back up was a good improvement.

A tank of gas later, still a very low and rough idle and the same 2 engine codes, only sometimes the CEL will only flash and not stay on. Also, fuel economy is still pretty poor.

My next thought is either change the fuel injectors, or simply fill her up with a tank of premium and some gum-out, and see if maybe #6 is just really caked in buildup after so long with the misfiring.

Any thoughts/suggestions? Thank you!

 

[wmburns]

The flashing CEL light means that a misfire is actively occurring.

It might be handy to re-post the DTC codes being to prevent confusion.

Have you confirmed the spark plug routing?
http://www.allfordmustangs.com/foru...king-rough-idling-injectors-next.html#2951811

Have you listened to each fuel injector to confirm a mechanical pulse? How about a "noid" test to confirm an electrical pulse?

Compression test?

 

[DomesticCars]

Spark plug routing is correct. Checked and rechecked.

The DTC codes are a P306 misfire in cylinder 6, and a P.... - Bank 2 too lean.

I'm gonna check the fuel injectors on Monday, and if those are fine the compression test is next. Any estimate on how much that test might run me?

Thanks everyone! :bigthumbsup

 

[MasterX]

The flashing CEL light means that a misfire is actively occurring.

Ya i saw this when i had to drive my car 5 miles with only 4 spark plug wires, had no choice, noone could run me up for wires, no other vehicles at the time, no friends or family were home, and had to work next morning.

Ran really bad, but she ran, didnt stall out, and was able to carry well enough to get to 55 and coast just above idle babyin the whole way with a trail of backfires from the non-firing cylinders.

 

[Denbar]

Spark plug routing is correct. Checked and rechecked.

The DTC codes are a P306 misfire in cylinder 6, and a P.... - Bank 2 too lean.

I'm gonna check the fuel injectors on Monday, and if those are fine the compression test is next. Any estimate on how much that test might run me?

Thanks everyone! :bigthumbsup

Before I ran a compression test, I would do a vacuum test on the engine. It will tell you if you need to run a compression test and it's a whole lot easier. Takes about five minutes, the gauges range from $ 23 to $50, and anyone should be able to do one.

Your codes would seem to point toward the #6 fuel injector. Try listening to it to see if you can hear it cycle of click. You can use a piece of hose or a long screwdriver to listen to it; one end to your ear and the other on the injector. If no clicking is heard it's probably bad.

Have you pulled the plug wire on #6 while it was running? If so, what happened?

 

[DomesticCars]

Fuel Injectors

In response to your C6 misfire, I had the same problem on an '01 v6 pony with 68k miles on it.

I replaced the EGR valve, cleaned all connections, new wires, new block, and did the high-octane and gum-out treatments. Each method worked for 10-15 miles, but as the car warmed up, it kept on happening.

Flashing CEL, rough idle, ****** acceleration, all the symptoms.

Pull off the manifold and go digging, I bet you've got a gunked up fuel injector on c6.

 

[wmburns]

Has the cam Sync sensor been replaced or altered? If so, was the correct alignment tool used?

While a very long shot check out this thread regarding a redesign of the V6 valve covers (oil baffles) to reduce excessive blow by entering the intake manifold.

http://www.allfordmustangs.com/forums/v6-tech/313594-1999-ford-mustang-3-8-a.html

Has the fuel injector pulse been confirmed? Has spark been confirmed?

 

[birdmann1995]

Hey guys, I have a 99 V6 3.8. It's been idling kinda rough. Engine shakes at idle. Shakes really hard in O/D at about 45 to 50mph. I've been dealing with that. But today I was leaving work and it ran just fine for a minute then I hammered on the gas and it started just like stumbling and fluttering. Now it idles like crap, seems like it has no power what so ever. I haven't had time to really try anything. It has a brand new coil pack, plugs and plug wires. Still through a #1 generic misfire code. When I shift to drive out of park it idles even worse. I'm just not sure what to do. Any help would be greatly appreciated.