2005 Town & Country, 3.8L. Engine cranks for several seconds before starting and then has an odor as if it is almost flooded. Once in a while it will start on first crank. have replace both O2 sensors and EGR. Latest codes have been P0456, P0300, and P0303. What should I replace next?


I do not have a diagram but, bank 1 is the bank where #1 cylinder is at. other side would be bank #2. so bank #1 o2 sensor is just before convertor.

Code p .0300 is multiple random misfires and that can be mostly a fuel pressure problem
p0303 is misfire on no 3 cylinder an injector problem
code p0 456 is EVAP system problem --small leak detected EVAP pressure sensor, mechanical fault--hose connections
check the fuel pressure and check for a problem injector seal at no 3 cylinder
it could be the source of low fuel pressure on starting

Below are the possible causes for your engine light and error code:

Possible Causes:

Check for

vacuum leaks on intake manifold,

the air tube between the air filter.

intake manifold vacuum hose.

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clean throttle plate with Berryman carburator cleaner

SEE sample picture HERE
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Also remove carbon built up behind the EGR valve and the EGR passage tube.

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Vacuum leak WILL offset the intended 14.7 to 1 air fuel ratio.

More un-metered air (leaks) will lean out the fuel mixture.

Use small amount of Berryman carb clearer at potential air leak area will help you identify trouble spot.

At idle,just spray and listen for the RPM surge.

The in-rush of carb clearer will increase the RPM on the motor.

Record the problem spot(s) and address it later.

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EGR carbon built up require 2+ hours to clean from start to finish.

You will need a new EGR base gasket before your start.

Locate and remove the EGR valve after the vehicle is cool down.

Carefully record the connector and vacuum line (for older vehicle) location by drawing an easily to follow diagram.

Remove the EGR valve.

Inspect the location of the carbon built-up inside the valve and the EGR passage tube.

SOAK these areas with WD-40 spary.

You will need a small screwdriver,cloth hanger and lot of newspaper and time to get this cleaning done right.

RE-SOAK the carbon and let it sit for over-night will also help.

One the last round,pass a shop vacuum of the EGR valve and the passage pipe.

Install the new EGR gasket and connectors.

Allow the vehicle to warm up outdoor to burn up any remaining WD-40.


Take it for a test drive.


Please rate my answer if it's useful to you.


Cheers,

Mustgo

Code EGR P404 is a problem with EGR (exhaust gas recirculaion), you have to replace the valve, check here for parts: partsamerica
The part costs $80/$100,. Having it done by a qualified mechanic, which is always the best choice costs around $250/$300.


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