1500 runs a little rough at idle and when i kick it down while driving it, it spits and sputters. any ideas? i have changed the 02 sensor and have a new cap and rotor not installed yet. but any other things to change??

 

If it was my truck I would put a new IAC, TPS, Spark Plugs, Wires, Cap, Rotor, and ignition coil. Could also be the timing is off.

 

Start with the easy stuff first, like, what you already have...... Definitely have a look at your plugs. Getting a check engine lite?

 

Timing is not adjustable, so don't try messing with it. Unscrew the o2 and leave it hang. Take it for a short drive and see what it does. You can also remove the TB and attached sensor's and clean every thing. While the TB is off, get a small mirror and flashlight to look around inside the intake for oil pooling. If you decide to try, be careful when cleaning the IAC, don't push pull or twist it.

 

Any trouble codes?

Always start with spark plugs for a misfire. They tell alot about what's going on inside the engine. The magnums use regular copper plugs, which should be changed every 30k. When you remove them, look closely at each one. If there is a lot of white crud on one or more, you likely have the plenum pan leak goin on. If they look mostly ok, just install the new ones and move on to check the ignition cables. If there are no signs of plenum pan gasket failure and it's still stumbling after you do plugs, wires, cap and rotor, then we get into more serious diagnostics.

 

I would have someone check your MAP sensor as well as the other sensors that were mentioned. MAP is the master sensor that controls the timing and the spark advance as well as monitoring the VAC level inside the intake.

Sputtering is also associated with LOW FUEL PRESSURE / FAILING FUEL PUMP.

Check the FUEL PRESSURE at the fuel rails and see what you've got. Get a hand held scan tool or, use the key on method to pull the 101 codes off the cluster.

CM

 

key method??? I know the cat is probably junk i think ill just cut it out.

 

The MAP sensor doesn't control anything. The sole function of the M(anifold) A(bsolute) P(ressure) sensor is to turn engine vacuum pulling against a diaphram into an analog electronic signal, which is then transmitted to the PCM, converted to digital, and used in conjuntion with inputs from all the other sensors for the logic circuit to determine the appropriate outputs (fuel trim, spark advance).

The MAP sensor signal is paired with vehicle speed and throttle position to determine engine load. A faulty MAP will not cause his misfire at idle.

This will end up being an ignition misfire, almost guaranteed.

 

I know this system pretty well, and, it was probably the choice of wording that lead to it reading that way, but, the fact is, the MAP does, in conjunction with the PCM controller, control the timing, A/F mixture, shift point strategy along with spark advance, Injector Pulse Width etc and, if it's out, it can lead to misfire condition. While you've got some of the information there, there's actually more going on with the MAP than what you've listed out.

The OP said he had a a rough idle to which, is why I mentioned having the MAP checked as, misfire can be induced by a faulting MAP sensor among a long list of other failures (see below) and, if the A/F mixture is leaned out too much or, the timing is out, you are going to witness a misfire condition. However, I do agree that, for a misfire, the most common mode of failure is either rooted at the plug, ignition wire, cap and rotor and coil component level. But, there's a whole slew of other failures that will also induce the same thing to occur.

The following are all possible root causes for misfire condition:

Faulting MAP sensor- throwing the A/F ratio out of whack along with erroneous voltage being sent to the PCM controller.

Failing fuel pump - low fuel pressure thus, leaning out the mix, thus, inducing misfire condition.

Failing coil - low or no voltage

Fault in the coil driver CKT

Failing spark plug/s

Incorrect heat range of plug, wrong type, wrong length, etc

Fouled plug

Induction cross-fire due to cheap ignition wires that are not routed per TSB

Arc-over inside of cap due to fault in coil driver CKT remaining ON at all times

Fault in injector driver CKT

Partially restricted fuel injector or, clogged fuel injector/s

Vac leak at the injector O-ring thus allowing unmonitored air into the chamber thus, leaning out the A/F mix thus leading to misfire

Vac leak at the TB / IAC O-ring interface thus allowing un-metered air into the intake thus, same as stated above- leaning out the mix.

Vac leak: check valve power brake booster - same affect as above.

Vac leak: plenum

High compression ratio due to carbon build up thus, creating a higher than normal heat range in the combustion chamber thus, heating up the tip of the spark plug thus, causing pre-ignition before piston reaches TDC


CM

 

There is a quick and dirty method of obtaining codes.

METHOD:

Turn the Key ON / OFF, ON / OFF, ON and leave it ON. The display will flash the engine illumination lamp. For example, for code 12, you will see it flash once, then, pause. It will then flash twice and pause. That's how it works with, 55 being the end of the KEY <ON> diagnostic cycle.

Then, you will write down the codes (if any) and then look them up on the net or, in the Haynes or Chilton manual.

CM