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Registered
96 Sedan DeVille 4.6L
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21 Posts
Discussion Starter #1
Original plugs are AC 41-947

Owners Manual specifies AC 41-900

Haynes Manual specifies AC 41-929

I think the plug wire set is 748J AC Delco


The vehicle runs fine at idle
In drive it stumbles and misses and backfires on occasion

I want to change the plugs and wires for starters

Would it hurt to run some injector cleaner through the gas tank?
Thanks
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,481 Posts
The recommended spark plug is the AC Delco #41-950 Professional Platinum, made by DENSO in Japan. Your engine may have come with DENSO plugs in it from the factory. Different year group, but mine did, and the owner's manual quotes a DENSO, not AC Delco, plug number. Notice the "Made in Japan" on the new plug boxes.

You'll probably find some oil on the plug shells and ceramic. Normal. Not to worry.

Get the plug wires - the expensive AC Delco set, from RockAuto. Remove the coils and ICM + base from the engine and clean everything. Make sure the ground cable from the ICM base is properly grounded. Clean the coil bases and contacts, use the diagram to make sure the proper coil tower goes to the correct plug.

If you want to feel warm and fuzzy and run something through the gas tank, use a 20 oz. bottle of Chevron TECHRON. It's a powerful fuel system cleaner, endorsed by GM and several other manufacturers. It is also a component of the Top Tier gasolines. Google "top tier gasoline" for background.
 

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Registered
96 Sedan DeVille 4.6L
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21 Posts
Discussion Starter #3
Thanks for the info Submariner...Also for the diagram that lays it all out..Looks like Rock Auto has everything I will need
Capt Deville
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,481 Posts
Either in this forum or in Northstar there's a recent thread on the ICM, its cleaning and grounding. Pictures.
 

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98 DeVille, 97 DeVille d'Elegance
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7,345 Posts
Give the TB a good cleaning while you're at it. Make sure to get the ICM ground back on when doing rear plugs.
 

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White Diamond '03 DHS (with DTS floor shift)
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86,785 Posts
Use the Haynes manual to sop up spilled fluids. Too coarse to use as toilet paper.
 

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Alexandra - 96 SDV Clyde - 15 Silvy
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6,394 Posts
I do believe the 748J set is the one with the specific lengths. Compare old plugs to new to get the lengths and order right. For some reason they didn't number the new plug wires, at least not on my new ones I got a while back.
 
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