I hope soneone has some idea what I may have done wrong here:
2002 Tahoe 4x4, 5.3L PFI Vortec E-85 engine, 65K miles. Ignition type : coils mounted on the valve covers, one per cyl and a short wire to the plug (not a coil pack).I changed the spark plugs (used to do that at 50K on my older vehicles but lost track of time. (Now I hear they're good for 100K but I'm hard to teach new tricks), but sadly used cheap Champion plugs from Meijer and may have mis-read the book at the store and got the wrong ones. It ran like crap, so I immedieatly went to my trusty NAPA and got the correct plugs (double platinum, $63 a set, holy crap!). My wife said it turned on the Check Engine light several times the day she drove it, but it's not on any more and there are NO codes stored, according to my cheap Accton OBDII scanner.
The manual and the tag under the hood say to gap at 0.060", but the NAPA computer said don't change from 0.040" pre-gap. I put them in at 0.040" and it runs pretty good, but after a day my wife complained of a rough idle. So I regapped them to 0.060", but it still idles rough. Not too bad, but definitely noticeable, and it hesitates a bit when accelerating from a dead stop.
The wire boots were quite difficult to pull off the plugs, could I have damaged one or more to cause this problem? It's another $70 for wires, and I'll replace them if I have to, but seems kind of drastic to have to spend $130 on a set of plugs. My next oldest vehicle is a 93, so I'm not used to working on Vortecs. Is there anything I need to do when changing the plugs?
Thanks in advance for any advice,
Scott Reese
93 GMC 2500 Suburban, 65K miles 02 Tahoe, 65K miles 89 Caprice Classic, 230K miles