2004 chevy impala 3400 engine the cars has new head gaskets and intake gaskets and new plug wires and spark plugs heads were shaved due to over heating.since replacing all these parts the engine missis and stalls and has no power.found that the catalast converter was glowing red after a few moments of running so gutted the catalyst but still no change valves are torqe to 17 ft lbs and it had over heated bad reason for all the work but before this engine ran fine.one of the o2 sensors behind catalast was burt looking and the wiring loom and engine light is on.any suggesetions to my problem with this would be greatly appreciated.are both the sensors on exhaust 02 and could the burt one be causing this.help seriously needed thanks

Assuming that the timing chain is in the correct position, and you do not have compression in any of the cylinders, you will need to check if any of the valved are bent by taking off the rockers and inserting air into the spark plug holes and see where the air goes. Either through the intake or the exhaust. If the air is escaping, then the pistons probably have hit the valves while they were open.

I doubt the problem is a head gasket.
It sounds like a wiring problem or something affecting the injectors and/or ignition. A very lean fuel mixture could cause the running rough and backfiring problems. So could an ignition problem where the plugs are firing on the wrong cylinders.
The V6 engine does use plug wires, and its possible some of the plug wires are on the wrong plugs.
A leaking intake gasket could also cause the symptoms.

everything in sync ?

Instructions

1. Removal

Unscrew the bolt that holds the negative connection to the Impala's battery. Set this bolt aside for later use.

Remove the engine cover to access the intake manifold and manifold gasket. Disconnect the throttle body inlet duct from the engine.

Twist off the radiator cap to allow draining of the coolant to flow more smoothly. Place an empty container beneath the radiator's drain plug, and remove this plug. Allow all of the engine coolant to drain into the empty container. Replace the drain plug once you are finished.

Tag all of the electrical wiring and hoses before removing so that reconnection is precise to factory settings. Remove these parts, individually, from the intake manifold.

Loosen the bolts that hold the intake manifold to the Impala's engine block. Lift the intake manifold from the block once all bolts have been completely removed.

Use the flat-head screwdriver to pry the old intake manifold gasket from the engine block. Discard this part once you have removed it.

Clean the engine block thoroughly with the engine degreaser and linen cloth. If necessary, use a gasket scraper to remove excess buildup and grime.

2. Installation

• Coat the top and bottom of the new intake manifold gasket with a chemical sealer so that it bonds to the engine block securely. Position this new manifold gasket so that it lines up perfectly with the cylinder ports of the Impala's engine block.

Place the old intake manifold on top of the newly-installed manifold gasket until it aligns with all of the holes of the cylinder flanges and manifold gasket.

Attach all of the bolts with your hand to the manifold. Once all bolts have been positioned, use a torque wrench and apply 15 foot-pounds of pressure to the bolts to secure the manifold into place.

Reconnect all of the necessary hoses and electrical wiring to the intake. Pour the engine coolant back into the radiator.

Reattach the engine cover on top of the intake manifold and engine block. Start the Impala's engine and check for any leaks around the new intake manifold gasket.

HAVE A BAD PLUG WIRE FROM DISTURBING STUFF OR CROSSED PLUG WIRE FOR A BAD ONE START IT UP AND TURN THE LIGHTS OUT YOU WILL FIND IT .

Please don't forget to rate. Thank you:

Left side front cylinder head



Cylinder head bolt torque sequence-3.4L engine

Cylinder head by aligning it with the dowel pins

New cylinder head bolts coated with a sealant (such as GM 1052080). Torque the bolts in the proper sequence (1-8) to 37 ft. lbs. (50 Nm). Using a torque angle meter turn the bolts 90 degrees in the proper sequence.

Left side exhaust manifold. Torque the bolts to 12 ft. lbs. (16 Nm).

Spark plugs. Torque the plugs 11 ft. lbs. (15 Nm).

Right side rear cylinder head:



Cylinder head bolt torque sequence-3.4L engine

New cylinder head gasket

Cylinder head on top of the gasket and make certain it is lined up properly with the dowel pins

New cylinder head bolts coated with a sealant (such as GM 1052080). Torque the bolts in the proper sequence (1-8) to 37 ft. lbs. (50 Nm). Using a torque angle meter turn the bolts 90 degrees in the proper sequence.

Right side exhaust manifold. Torque the bolts to 12 ft. lbs. (16 Nm).

Spark plugs. Torque the plugs 11 ft. lbs. (15 Nm).

Spark plug wires

Exhaust crossover pipe. Torque the fastener to 18 ft. lbs. (25 Nm).

Valve rocker arms and pushrods. Torque the fastener to 89 inch lbs. (10 Nm). Using a torque angle meter torque the fastener an additional 30 degrees.

Lower intake manifold. Torque the bolts to 115 inch lbs. (13 Nm).

Upper intake manifold. Torque the bolts to 18 ft. lbs. (25 Nm).

coil or electronic ignition module going off when turning warmer.i guess run some test

Check if you have spark at the spark plug. Go buy yourself one plug. Take any plug wire off plug in engine. Attach plug wire to new plug and touch a ground on engine with new plug threaded side. Have someone start engine and watch for spark. If spark exsist, look for fuel problem.

2.2L Engine

1. Observe the following service precautions:
   
   Allow the engine to cool before removing the spark plugs. Attempting to remove spark plugs from a hot engine can cause the spark plugs to seize. This can damage the cylinder head threads. Clean the spark plug recess area before removing the spark plug. Failure to do so can result in engine damage due to dirt or foreign material entering the cylinder head, or in contamination of the cylinder head threads. Contaminated threads may prevent proper seating of the new spark plug. Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.
   
2. Turn the ignition OFF .
3. Disconnect the Electronic Ignition (EI) module harness connector.
4. Remove the spark plugs using a 5 / 8 inch spark plug socket.

To install:

WARNING Do not coat spark plug threads with anti-seize compound. If anti-seize compound is used and spark plugs are over-torqued, damage to the cylinder head threads may result.

1. Inspect the gap on the new spark plugs, re-gap the plugs as required. The spark plug gap specification is 42 inch. (1.0 mm).
2. Install the spark plugs and tighten to 15 ft. lbs. (20 Nm).
3. Apply dielectric compound to the spark plug boots and make sure no corrosion is present.
4. Install the ignition coil housing to cam cover and attachment bolts.
5. Tighten the ignition coil housing bolts to 89 inch. lbs. (10 Nm).
6. Connect the EI module harness connector. Push in until a click is heard and pull back to confirm a positive engagement.

hello your intake gasket is most likely leaking internally into your engine.pretty common problem.the plastic and silicon gaskets get weak over time.