99 Ranger 4.0 Rough at start up

[NORDFORD]

Throwing codes p0303 and p0304. Plugs, wires, coil, fuel filter, air filter were new in September, and have less then 5,000 miles on them. Also cleaned the MAF and IAC.

It only runs rough at start up. After it warms up, it runs normal. Disconnected the battery to clear codes, and they came right back.

Any ideas? Thanks guys.

 

[BuckeyeSlim]

disconnecting the battery on a OBD II system will not clear codes... most likely cause is the intake plenum gaskets causing a massive vacuum leak untill they warm up and expand to close off the leak. my 4.0 explorer does that when its cold ( i kinda like the way it sounds though makes it sound cammed) lol good luck

 

[muhl5443]

if u disconnect the battery for 30 sec. or more the codes will be erased.
IF THEY CAME RIGHT BACK THEN IT MEANS YOU HAVE A PROBLEM
it is not a vacuum leak problem those are codes p0171 and p0174.
p0303= u might need to replace computer. i ran the codes through a site that i use at work and both codes came up and said that they were still coming back on and the pcm needed to be replaced. otherwise it the ignition coil or the throttle pedal position sensor.

Potential Causes
Connector
Harness
Defective Powertrain Control Module (PCM) Driver
Engine Mechanical
Fuel Injector Lean running condition due to a fuel injector flow problem
Confirmed Fix
1 - Ignition Coil
1 - PCM Wiring
1 - Powertrain Control Module (PCM)
4 - Both Cylinder Heads
1 - Both Cylinder Heads, Cylinder Head Gasket
1 - Cylinder Head Gasket
1 - Cylinder Head Gasket(s)
1 - Engine Carbon
1 - Intake Manifold Gasket(s)
1 - Spark Plug Wire(s), Spark Plug(s)
the numbers correspond to # of confirmed fixes
p0304= same stuff as p0303