DFBonnett Posted August 7, 2004 Report Share Posted August 7, 2004 I put new AC Delco plugs, #41-902 with the platinum tips, in the car at 37K in 1998 because of a bit of roughness and vibration at idle. At the same time I replaced the OEM wires with Standard brand along with the cap and rotor. It idled smoothly after that. I'm now at 58K and the roughness has slowly returned along with a drop in mileage. I pulled plugs 1, 3, 5, and 7 from the front bank. With only 21K on the plugs, the platinum tip was missing on the side electrode (strap?) on #1 and #3 and the gap was, concomitantly, way beyond .060". Otherwise, the plugs looked fine. After swapping out those two plugs with two better ones retained from the previous set, the car idled a good bit better. I didn't pull the rear bank as I intend to replace all the plugs now. Is there any reason why the service life of the plug was so short? Should I be using a different plug on a '93 4.9? AC Delco still lists this plug for the application. Any opinions on the Standard wires? Should I replace them with OEM while I'm at it? DFB Link to comment Share on other sites More sharing options...
KHE Posted August 8, 2004 Report Share Posted August 8, 2004 The pad weld was greatly improved about 5 years ago or so. I would replace the plugs that have the ground electrode pad missing. I removed the plugs in my '93 Fleetwood Brougham four years ago and 4 of the 8 plugs were missing the platinum pad on the ground electrode. Ironically, the car was not missing or running rough. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
sprucegoose Posted August 8, 2004 Report Share Posted August 8, 2004 Yes, I had heard that the process had been improved, and they were much more dependable now. I had the original set in my 98 Tahoe till about 88k when al of the sudden they started plopping off. Now have 152k on that truck and they look like new yet. One thing that did strike me, is how few miles that you put on your car... Kind of the exact opposite of me! I am wondering if this has something to do with limited plug life too. A lot of short hops down the street to the store for example, vs. long highway drives that get the motor and plugs burning nice and hot can make a difference... '09 Cadillac CTS-4 3.6 direct injection, 128 K mi. '15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi '70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration! Link to comment Share on other sites More sharing options...
rek Posted August 8, 2004 Report Share Posted August 8, 2004 OEM wires are the way to go. I think they might even come with a 5Yr./50K warranty. rek Link to comment Share on other sites More sharing options...
TomCalliham Posted August 8, 2004 Report Share Posted August 8, 2004 When the platinum tips come off ,where do they go??? Platinum is a really hard metal so you'd think that would or could do some damage to the engine. ??????????????????????????????????????????????????????? Link to comment Share on other sites More sharing options...
JasonA Posted August 8, 2004 Report Share Posted August 8, 2004 When the platinum tips come off ,where do they go??? Platinum is a really hard metal so you'd think that would or could do some damage to the engine. ??????????????????????????????????????????????????????? On another board I follow, a fellow is involved with Infinity Q45 cars (so I'm twice removed from that), but he swears many times AGAINST the Bosch 2x and 4x platinum plugs because the pads have come off on in many Q45 installations and scored the cylinder walls bad. Again, I'm a few steps removed from the original discussion there, but this topic has apparently come up before. Jason(2001 STS, White Diamond) "When you turn your car on...does it return the favor?" Link to comment Share on other sites More sharing options...
Scotty Posted August 8, 2004 Report Share Posted August 8, 2004 When the platinum tips come off ,where do they go??? Platinum is a really hard metal so you'd think that would or could do some damage to the engine. ??????????????????????????????????????????????????????? On another board I follow, a fellow is involved with Infinity Q45 cars (so I'm twice removed from that), but he swears many times AGAINST the Bosch 2x and 4x platinum plugs because the pads have come off on in many Q45 installations and scored the cylinder walls bad. Again, I'm a few steps removed from the original discussion there, but this topic has apparently come up before. Tom and Jason, that is an excellent thought, I thought that the platinum pad could score the cylinder walls, if it lodged itself in a bad spot. I have seen bbobynski mention that the pads are blown out of the cylinder, but what if they are not? Mike Link to comment Share on other sites More sharing options...
Ranger Posted August 9, 2004 Report Share Posted August 9, 2004 Those pads are so tiny I would bet they will pass right through the engine without so much as a hicup. While anything is possible I wouldn't loose any sleep over it. Link to comment Share on other sites More sharing options...
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