Gents

New-to-me 2006 1500 SLT 4x4 4.7L (79K mi)

Discovered what has to be original plugs badly worn. Gaps had opened up to 0.90" (!) Installed new plugs (0.40") without bench testing the COPs.

Truck runs great as it did before. Now I've got gnawing doubts about potential effects of coil damage showing up down the road.

2 Q's:

1. For the 4.7L motor, what's the likely risk of weakened COPs from running plug gaps way too many miles over 2X spec?

2. What's the spec for bench testing COP's on a '06 4.7L?

Many TIA.

 

If it's running good, no codes, fuel mileage back up. IMO I would not worry about it.

 

Thanks for your reply, P38.

No codes before or after plug replacement. But I've been fiddling around under hoods for a long time. Having learned a pile of stuff both the hard way and the easy way, I much prefer the latter. By my experience, whenever there's a choice, staying in front of dubious stuff is well proven best.

FWIW, I stumbled across this COP spec for the 4.7L in my Haynes (aka Heinous) manual:

Primary resistance: 0.6-0.9 ohms

Secondary resistance: 6-9 K-ohms

Will test and replace as needed.

Anybody else got any more wisdom and experience on this?

Bueller?

 

have to agree with p38251
yes, it will put stress on the coils... but if they all are alive keep on trucking.

my old 2000 gmc when i got it had the center electrodes worn to the ceramic...truck still ran with no missfires or loss of power with the old plugs....coils are still going strong 1.5 years later. new plugs then fahgetaboutit.

if the plugs are that bad; check the fuel filter if it has an external filter.

 

Thanks primem.

I started checking, found every one well within spec, all consistent within a few tenths, decided by #4 it was getting silly, and called 'em all GTG.

You guys were right on. Many thanks again.