It's the second (bottom) diagram in your post. #4 is the driver's side, closest to the radiator. If you have Motorcraft wires, they are numbered.

As far as the coil pack goes, it is actually 3 independent double-ended coils in one assembly, so you can have a partial failure.

 

Try plugging the MAF back in...

Seriously, though, except for the code it threw, those are often the symptoms of a MAF that is not plugged in.

 

I know.. been there, done that

Were gonna hope for the best and say its a plug or wire

If it were a partial coil pack out that would affect two cylanders then, and I'm only getting the one misfire...?

Well its gonna have to wait till morning cause its dark and I'm hungry, at least now I know what the problem is, now its just finding its source... oh boy

 

Most likely, but the misfire monitor may not report both cylinders right away.

I don't believe that your coil pack is the problem in this case, just responding to your statement that the CP would affect all cylinders.

 

When you change the IAC you must also reset the computer.

 

You can forget about the IAC. It only controls idle air flow and preposition for the dashpot function. It will work fine without a reset - the only problems could be a dip or flare when changing transmission or AC modes. It will eventually learn its way out of these, even without a reset.

The IAC has nothing to do with A/F ratio, ignition or EGR flow; these are the things to consider when working on a hesitation or bucking problem.

 

I had a 94 tbird with the 4.6... had a wire go bad and start grounding out...

Also a few monthes later one of the coil packs went bad which killed 2 cyl only not 4. There is a way to check them with an ohm meter but i dont remember.

Also what wires did you use.. if its the autozone special.. that could be an issue.

Rand

 

Yea the IAC was on its way out so it need a change anyway, it was a longshot and ended up being not the problem anyway.

The wire are good wires, maybe a bad one sliped in or this plug just took a dump, I'll know more in the morning.

Thanks for the help for sure!!

 

Not really -- but your idle will stabilize quicker if you do the reset, so it's a good idea. The PCM is always re-learning idle strategy, but on a "damped" basis if you will. When you reset, it becomes more "aggressive" about rebuilding the tables.

 

After a reset and before driving the truck, the PCM relearns the default IAC airflow rates for 4 idle modes

Neutral w/o AC
Neutral w/AC
In gear w/o AC
In gear W/AC

(manual trans trucks have only the 2 neutral modes):

The correct flow rates can be established within one minute in each mode provided that the engine is at operating temperature. Once the truck has been driven, the PCM learning rate for the default flows becomes much slower, to adjust for changes in average ambient temperature, barometric pressure, engine wear, etc.

The IAC flow rate and ignition timing are constantly being adjusted by the PCM to maintain the correct idle speed. The 4 learned settings for the IAC flow rates are only used briefly at the initial change from of the 4 modes to another. Failing to reset the PCM simply lengthens the time it takes for the IAC mode default values to be learned. During that time, there may be dips or flares in idle speed as the engine is changed from one mode to another. Examples would be shifting from Neutral to Drive or Reverse or as the AC compressor cycles.

I'm not implying that the PCM shouldn't be reset. But I am saying that the lack of a PCM reset is not causing the hesitation. In fact, I would say that the IAC is not involved in the hesitation at all.

 

I have to agree with that. The IAC has nothing to do with this problem anymore, and swithcing it didnt cause anything get better or worse.

Off to change some plugs/wires

 

Some possibilities for a bog/hesitation:

Bad fuel
Weak ignition
Too much EGR flow
Throttle Position Sensor
MAF Sensor

 

Fuels new
No EGR
TPS Cleaned
MAF Cleaned

Changed the plug in Cylinder 4, and its idleing perfect. Time to go road test it, but I thougt I'd put this photo up before I leave. What do you think this plug is trying to tell me?

 

I don't see anything wrong. Inspect the white insulator (the part inside the socket in your picture) carefully for cracks. A cracked insulator can cause all sorts of problems.

 

Insulator looks perfect and plug looks good. Guess we'll just have to call this one a dead plug... Thanks for the help Bob I really appreciate it!

 

Could that really make a howling noise? Cause at the moment I have the same noise. And mine too shuts up when you hit the gas. I guess if itz not that expensive I will just go ahead and do it.

 

You ever get this figured out?>