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46 Posts
Discussion Starter #1
Anyone have a step by step on how to change an intake gasket?

I have a 96 Concorde 3.3 with 131K miles. The CEL was on a few months ago, showing a cylinder 6 misfire (12,43,55..then confirmed at AutoZone). I replaced the plugs and wires, and reset the CEL, only to have it come back with the same codes about a month later (car is driving 10 miles a day, max).

My next guess is the intake gasket. Are these hard to replace? I have done quite a bit of the work on the car myself (IAC valves, brakes, fuel pump, water pump, MAP sensor, CAM sensor...that kinda stuff).

Will this project be over my head? More importantly, will it fix the problem?

Thanks in advance,

0 Posts
I don't think the intake gasket would be causing a misfire. More likely a bad plug wire, a defective ignition coil, or even a clogged or dead fuel injector. Beyond that its engine mechanical problems.

177 Posts
Spray carb cleaner at the manifold near #6 cylinder at idle. If the idle changes yoy have a gasket leak. A cracked gasket at #6 is common.

9,861 Posts
izzay said:
I don't think the intake gasket would be causing a misfire.
Yes, it would.

1,675 Posts
I replaced the intake gasket on my 95 3.3. It wasn't that hard, the way the engine is placed makes it easy. However, mine wasn't soo easy. One of the intake manifold bolts was broken, and the other half was stuck in the head. Took two hours to get it out. I STRONGLY reccomend getting all new bolts for the intake manifold from the dealer. Only three of the ones I took out were reuseable. Also, be careful with the fuel rail. Those clips where it plugs in to you have to remove. One of mine broke after I did it, so I had to have the dealer put a new one on. Now the other one broke, and my car is sitting because of the massive gas leak.

Here are some pics:


Dont forget to put the injector harness back in before you bolt everything down.

3,041 Posts
Here's a How-To:

Intake Manifold


3.3L Engine

See Figures 1 through 20

The intake manifold is a tuned two-piece aluminum casting with individual primary runners running from a plenum (the upper part of the manifold). The intake manifold assembly is cored with upper level EGR passages for balanced cylinder-to cylinder EGR distribution. These openings should be inspected and cleaned if necessary whenever the manifold is removed for service. Use care when working with light alloy parts. Do not over-tighten any fasteners or the casting may be damaged.

Disconnect negative battery cable.

Remove the fuel filler cap. Release the fuel system pressure using the recommended procedure.

Drain the cooling system.

Disconnect the air tube from the air cleaner and the throttle body.

Hold the throttle lever in the wide-open position and remove the throttle cable and the speed control cable from the lever. Compress the locking tabs on the cables and remove from the mounting brackets.

Fig. 1: Compress the locking tabs on the throttle and cruise control cables and remove them

Unplug the electrical connector from the solenoid on the EGR valve transducer, MAP sensor, throttle position sensor and the idle air control motor.

Fig. 2: Disconnect the solenoid from the EGR transducer

Fig. 3: Label and remove any vacuum hoses attached to the intake manifold

Disconnect the vacuum hose from the PCV valve as well as the power brake booster at the intake manifold nipple. Disconnect the vacuum line at the fuel pressure regulator.

Fig. 4: Disconnect the electrical harness leading to the MAP sensor

Fig. 5: Disconnect the vacuum hose from the PCV valve

Disconnect the purge hose from the throttle body.

Unplug the electrical harnesses from the throttle position sensor and the idle air control motor.

Fig. 6: The throttle position sensor is located on the side of the throttle body, disconnect it

Remove the EGR tube mounting screws at the intake manifold plenum.

Fig. 7: Unscrew the EGR mounting tube at the intake plenum

Remove the intake manifold plenum (upper part of the manifold) mounting bolts and remove the plenum from the engine. Cover the lower part of the intake manifold to prevent foreign material from entering the engine.

Fig. 8: Remove the intake manifold plenum mounting bolts

Fig. 9: Double check everything is detached, then lift the plenum off the lower manifold

Fig. 10: Fill the lower intake openings with clean rags

Disconnect the fuel supply and return tubes to the fuel rail at the rear of the intake manifold by pushing the quick-connect fitting toward the fuel tube while depressing the built-in disconnect tool with Quick-Connect Fitting Tool 6751. To disconnect the fitting from the fuel rail, slightly twist the fitting while maintaining downward pressure on tool 6751. Wrap shop towels around the fuel hoses to absorb any fuel spillage.

Fig. 11: Disconnect the fuel supply and return tube quick-connect fittings art the rear of the manifold

Cover the fuel line openings to prevent system contamination.

Remove the screw from the fuel clamp and separate the fuel tubes from the bracket.

Fig. 12: Remove the fuel rail mounting bolts

Tag each connector for identification, then disconnect the electrical harness from the injectors and turn toward the center of the engine.

Remove the fuel rail mounting bolts and lift fuel rail with the injectors attached straight up and off the engine. Cover the injector openings.

Remove the upper radiator hose, heater hose and the rear intake manifold hose.

Fig. 13: Loosening and tightening sequence for the intake manifold bolts-3.3L engine

Remove the intake manifold bolts and the manifold from the engine.

Fig. 14: Remove the intake manifold bolts ...

Fig. 15: ... then lift the manifold from the engine carefully

Remove the intake manifold seal retainers screws and remove the intake manifold gasket. Clean all mating surfaces.

Fig. 16: The intake manifold gasket cannot be removed until the retainers are removed

Fig. 17: The retainers are held in by screws on the ends of the block

Fig. 18: Now you can easily lift the intake gasket off the engine block

Inspect the manifold for damage, cracks or clogged passages. Repair, clean or replace the manifold as required.

To install:

Verify that all intake manifold and cylinder head sealing surfaces are clean. Place a drop of sealant onto each of the four corners of the intake manifold gasket, where the cylinder head meets the engine block. Carefully install the intake manifold gasket and tighten the seal retainers to 105 inch lbs. (12 Nm).

Fig. 19: Apply a bead of sealant on each of the four corners of the intake seating

The intake manifold gasket is made of very thin metal and can cause cuts if handled carelessly.

Install the intake manifold and eight mounting bolts. Snug down evenly to just 10 inch lbs. (1 Nm).

Tighten intake manifold bolts in the proper sequence to 16 ft. lbs. (22 Nm). Once all bolts are tightened, repeat the sequence again tightening the bolts to 16 ft. lbs. (22 Nm). Inspect to make sure all seals are still in place.

Apply a light coat of clean engine oil to the O-ring on the nozzle end of each injector.

Insert the fuel injector nozzles into the openings in the intake manifold. Seat the injectors in place and install the fuel rail mounting bolts, tightening to 16 ft. lbs. (22 Nm).

Attach the electrical connectors to each fuel injector. Rotate the injectors toward the cylinder head covers.

Reconnect the fuel supply and return tubes to the fuel rail. Be sure that the black plastic release ring to the quick-connect fitting is in the OUT position. Place special tool 6751 under the largest diameter of the quick-connect fitting.

Pull Tool 6751 toward the fuel rail until the quick-connect fitting clicks into place. Place the special tool between the shoulder of the built-in disconnect tool and top of the quick-connect fitting, then inspect the security of the fitting by applying a slight downward force against the fitting. It should be locked in place.

Install the intake plenum with new gasket onto the intake manifold. Loosely install the mounting bolts.

Fig. 20: Tightening sequence for the intake plenum-3.3L engine

Install the EGR tube to the manifold with new gasket in place. Loosely install the mounting screws.

Tighten the intake manifold plenum mounting bolts to 21 ft. lbs. (28 Nm) following the outlined sequence.

Tighten the EGR tube mounting bolts.

Reconnect the PCV valve hose and power brake booster hose.

Attach the electrical connectors to the EGR transducer solenoid, idle air control motor, map and throttle position sensors.

Install the throttle cable and speed control cable to the mounting bracket and connect to the throttle body lever while holding lever in the wide-open position.

Reconnect the purge hose to the throttle body. Reconnect the air tube to the air cleaner and the throttle body.

Drain and replace the engine oil and oil filter.

Reconnect the negative battery cable. Refill the cooling system. Run the vehicle with the radiator cap removed until the thermostat opens, adding coolant as required. Watch for fuel and coolant leaks and for correct engine operation.

Once the vehicle has cooled, recheck the coolant level and add, if necessary.

1,672 Posts
izzay, that's one of the most common causes of misfires in our cars

3,041 Posts
Yep, I agree with everone else about the Intake Gasket. But did you look at the Plug wires and the connections at the Coil ? Also you can test the coil too just to be on the safe side. You should cover all the easy stuff first !

Here's how to test the coil just for you info:

Coil Test

See Figures 2, 3 and 4

Fig. 2: The ignition coil connection terminal descriptions

Fig. 3: Check the primary resistance at the electrical connection and the secondary resistance across the coil towers

Fig. 4: Ignition coil terminal identification

Coil one fires cylinders 1 and 4, coil two fires cylinders 2 and 5, coil three fires cylinders 3 and 6 for the 3.3L and 3.5L engines. Each coil tower is labeled with the number of the corresponding cylinder.

Unplug the ignition cables from the coil terminals and the spark plugs. Make certain to label them before removal. Measure the resistance of the cables. Resistance must be between 3,000-12,000 ohms per ft. (30.5 cm) of cable. Replace any cable not within tolerance.

Unplug the electrical wiring harness connector from the coil pack.

Measure the primary resistance of each coil. At the coil, connect an ohmmeter between the B+ pin and the pin corresponding to the cylinders in question. Resistance on the primary side of each coil should be 0.45-0.65 ohms at 21-27°C (70-80°F). A coil not allowed to cool down, could result in inaccurate measurement results. Replace the coil with a new one if the resistance is not within tolerance.

Remove the ignition cables from the secondary towers of the coil. Measure the secondary resistance of the coil between the towers of each individual coil. Resistance for these engines depends on which manufacturer made the coil being tested. If the coil was manufactured by Diamond, the resistance should be 7000-15,800 ohms; if the coil was made by Toyodenso, the resistance should be 7000-15,800 ohms. If the coils' resistance are not within specifications, the coil must be replaced

46 Posts
Discussion Starter #9
That gasket looks a bit over my head. I DO have a trusted mechanic that has worked on the car before when things are above my scope of expertise. How much (ballpark...) should I figure this to cost me?

I forgot to mention the plug wires and plugs were new, of course...The coild might be the last thing to try...


Do you have a picture of where I should spray the carb cleaner?

Thanks again, everyone...
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