Northstar v8 2004 Pontiac GXP ignition engine error spark plug #5 bad, The distributor less ignition on back side identical to the front side but is extremely difficult to get to. Spark plugs did not appear to be bad or fouled when I replaced them. I would like to swap the the assembly to the front before I reassemble so that if the ignition module is bad I can replace the unit on the front side -10 minutes to replace.

1. Connect the distributor's B+ (battery) terminal to a switched 12-volt source, such as the ignition switch.

2. Connect the distributor's tach terminal to the tachometer signal wire, if you have a tachometer.

3. Connect the distributor's ground wire to a good engine ground.

4. Connect the distributor's #1 spark plug wire to the #1 spark plug on the engine. The #1 spark plug is usually located on the driver's side front cylinder.

5. Connect the remaining spark plug wires in firing order sequence to the distributor cap terminals. The firing order for a Buick 455 engine is 1-8-4-3-6-5-7-2.

6. Install the distributor cap and rotor.

Valve 6 will be the last plug on the Drivers side so that is
the # 6 plug as well on your Pass side it will be
#1 # 3 # 5 with # 1 in front and #3 in middle and # 5 closest to
firewall. and on drivers side # 2 # 4 # 6 with #2 closest to radiator
or front of motor, and #4 in middle, and #6 at the end by firewall.
hope this helps.

theres no distributor and the firing order for your 3.8 is 1-6-5-4-3-2-the following link shows the coil pack
Buick General Motor 3800 V6 Engine Firing Order DIS IDI ignition timing 3.8 Buick Engine Coil Pack Firing Order Spark Plug Wire Location Which way do the spark plug wires go on & what cylinder is what?
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For the Buick V6 231 3.8 liter turbocharged engine:
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Answers!
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Firing order:
1 - 6 - 5 - 4 - 3 - 2.
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Spark plug wire location on coil pack:
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Closest to the back of the car, left to right: 1 - 5 - 3.
Closest to the front of the car, left to right: 4 - 2 - 6.
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Spark plug wire location on engine:
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drivers side, front to back of car: 1 - 3 - 5.
passenger side, front to back of car: 2 - 4 - 6.
.----and this link shows the coil pack to cylinders
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3 8 Buick Turbo Engine Coil Pack Firing Order Spark Plug Wire Location

if you have multiple coils then there will be a regular misfire on a particular cylinder. If you have sets of coils then the coil that handles a set of plugs will misfire on those plugs. If you have one coil to do the lot then indicators are engine will not start, coil lead will show a weak orange spark when sparked to metal, engine will start fine and run for a period of time before the coil overheats and starts to break down ( misfiring), coil is very hot to the touch (burning ) after minutes of operation.

Look at the modulator on the side of the transmission. It's probably gone bad.

OKAY STANDING IN FRONT OF ENGINE ON LEFT SIDE CYLINDERS FACING YOU IS 1 3 5 ON RIGHT SIDE DRIVER SIDE CYLINDERS FACING YOU IS 2 4 6 LOOKING AT DISTRIBUTOR CAP NUMBER 1 SPARK PLUG ON CAP IN THE 9 OCLOCK POSITION YOUR NUMBER 5 SPARK PLUG ON DISTRIBUTOR CAP IN 6 OCLOCK POSITION .STARTING AT NUMBER 1 SPARK PLUG ON CAP COUNTING CLOCKWISE COUNTING 1 2 3 4 5 6 THATS YOUR SPARK PLUGS WIRES ON CAP TO ENGINE PLUGS. 6 PLUG WIRE ON CAP IS AT 7 OCLOCK POSITION.

Hi: To Install the Distributor Correctly, 1st thing to do is Remove your #1 Spark Plug assuming it will turn over have someone Turn the Key Off and On in Short Intervals.Either put a Compression Gauge in the #1 Spark Plug HoleOr the Old Fashion Way Works as well just put your Finger in the #1 Plug Hole.As your Helper Cranks the Engine On -Off On -Off.Not A Continuous Crank.When You Feel Air Pressure or See gauge Come up.TYhats when your Engine is a The compression Stroke.Now you Can Drop the New Distributor in its Hole.NOTE: You'll need a Spark Plug and Timing Diagram to See the Position your Distributor ROTOR Line it up to where the Diagram Shows your #1 Spark Plug Wire Will go in the Distributor Cap.If the Distributor Rotor is Not n That Position Your goning to Get Either Back Firing engine May Not Even Stsrt, To This Is Crucial. After The Know that you have The Distributor Droppped The Right position you'll need to Put Gap your Plugs at the Correct Specs, With All Plugs in Now You'll need to Put New Plug Wires on .And They MUST be in the correct order.Sitting inside your Vehicle #1 Plug is the Front Plug on the Drivers Side Next is #3 plug Next is #5 and Your Back Plug is Number 7,On the other side Passenger Front Plug is #2 next #4 Next is #6 and the Back is #8 Assuming you know have your Distributor Dropped in The Proper Position, Put the #1 Spark Plug Wire on the Front Spark Plug (Drivers Side) The Spark Plug Firing Order in Your Engine is 1-8-4-3-6-5-7-2 Clockwise So the Next hole after you have #1 Plug and Wire on And Distributor In Correct Position on COMPRESSION STOKE, Going Clockwise you next wire will be your #8 Position in The Cap And it wil go to the Back Spark Plug on The Rear Spark Plug on Passenger Side. NOTE: Drivers Side Spark Plugs on the Drivers Side Front to Back are Your Odd Numbers 1-3-5-7 Pasenger Side is Your Even Numbers From The Front is #2-4-6-8 Is The Rear PLug .

Heres a Diagram of your Spark plug Positions

Front of Engine
1 2
3 4
5 6
7 8

Hope This Will Get You Going. Let me know The Quality of Help and Solution I've Given You By Voting on It.And May Can Also Send a Testamony
From d_hubbs

350 Chevy engine in what? 1990 Corvette? Who built it, did you?

Sounds as though you have plug wires wrong.
Firing order is 1-8-4-3-6-5-7-2

Distributor Ignition System:
Distributor rotates Clockwise. (Rotor)
Find Number 1 tower on distributor cap, go Clockwise with Firing Order.

Distributorless Ignition System:
VIEWING the engine from the Front of the car.

Spark plug wire connections along the back, starting from Left side going to Right side;
2-3-7-4

Spark plug wire connection towards the Front of the engine;
6-1-5-8

(To guess I would say you have 5 and 7 wires switched)

Left side cylinder order is 1-3-5-7, going from front to back.
Drivers side is Left side.
Right side cylinder order is 2-4-6-8, going from front to back.

Since you didn't state whether it is a V6 or V8, I'll give you both.

V6 -4.3Liter
Firing Order is 1-6-5-4-3-2
Distributor rotor turns Clockwise
Number 1 spark plug tower on distributor cap, faces the front of the engine.

->Drivers side, spark plug order in engine, starting from the Front going back:
1-3-5
->Passenger side, spark plug order in engine,
starting from the Front going back:
2-4-6

If it's Electronic, the distributor cap has a Left side, (Drivers side), and a Right side, (Passenger side)
Starting from the Front, going back on the Left side,
3-1-5
Starting from the Front going back on the Right side,
2-4-6

V8-5.0, 5.7, and 7.4Liter
Firing Order is 1-8-4-3-6-5-7-2
Distributor rotor turns Clockwise
Number 1 spark plug tower on distributor cap,
faces Front, towards the Drivers side.

Electronic distributor cap has two sides. Drivers, (Left), side and Passenger, (Right), side.
Starting from Front going back on Drivers side,
1-7-3-5
Starting from Front going back on Passenger side,
8-2-4-6

Spark plug order in engine, starting from Front going back, Drivers side:
1-3-5-7
Spark plug order in engine, starting from Front going back, Passenger side:
2-4-6-8

Hello; yes i believe u are right about the #6 cylinder location, let me confirm it, if you are standing in front of your car cylinders,2, 4, 6, & 8 are the ones, from left to right in front of the radiator,cylinders 1,3,5 & 7 are the ones closest to the fire wall. sounds like u have a miss gaped or bad plug, i had a simular problem in my northstar. hoe we helped & good luck to u.