Spark Plugs

1999 GMC Sierra 1500 C1500 4WD ext cab 104k mi. 1) Dealer suggests new spark plugs and wires, but no “check engine” light. $460. Pros and cons?

2) Anyone have any hard info re: “Pulstar” spark plugs, e.g. actual controlled fuel economy tests? Thanks!

Are you saying you have 104,000 miles on a set of spark plugs and you question the technical advice to have them replaced?

What engine does this thing have in it? The estimate sounds absurdly high to me, but I suppose it is the dealer and if this has a big V8 in it it could be labor intensive. I’d suggest on a vehicle this age and out of warranty, to take to a good independent mechanic who can probably do it for half the price.

As for the pulstars consider two things. One, the only thing a spark plug needs to do is ignite the fuel-air mixture. Either it does or it doesn’t. Your stock ignition system with regular old plugs does it just fine and the best spark plug in the world isn’t going to do it any better. Also, consider that electricity follows the easiest path-- on a multi-electrode spark plug, only the electrode that happens to have the narrowest gap or lowest internal resistance will actually be used at any one time. The one advantage to them is that they take longer to foul because the electrodes get fouled one at a time, but plugs don’t foul unless you’ve got some serious problems.

No matter what plugs you have, if you have 100k on them, change them. As for wires, I don’t replace them unless they’re actually bad. I test them and see if they follow spec, and I check to see if they leak.

I’m skeptical on the Pulstar plugs. I need more technical data, not marketing data.

Regarding the Pulstars, I’m skeptical because the ad I saw had ‘us’ vs ‘them’ photos that looked like they were actually just a series of 4 pictures of the same spark plug. I smell ‘booooogus’…

No matter what plugs you use, you won’t get better gas mileage out of that vehicle. Mine gets 13 to 17.5 MPG. The dealer wants way too much money to change the plugs. Go somewhere else.

If it’s never had the spark plugs replaced, they could probably stand to be done. Wires, I’d only suggest if the truck has a lot of misfirings and the new plugs don’t cure it.

What I don’t understand is why you’re taking an almost 10 year old truck to a dealer. They’re way more expensive than independent shops in pretty much every aspect. $460 for plugs and wires is beyond absurd…you could do that yourself for barely more than 10% of that price.

I wouldn’t waste money on “Pulstar” or any other fancy multi-electrode plugs. They serve exactly the same purpose as OEM spark plugs, the only difference being the price.

To answer your questions. Yes you need to replace the plugs after 100k miles and the engine light shouldn’t come on to tell you that unless you’ve left them in so long the car is misfiring. I don’t know how quality the wires are on that Chevy, as I tend to only deal with imports, but given the low cost of a quality aftermarket wire set it wouldn’t be a bad idea to change them while you’re doing the plugs. One less thing to worry about 3 years from now. Ideally you’d check each one for resistance and cracks, but if someone else is doing the work they might as well replace them given the time it takes to check and test each wire correctly.

As for the Pulstar plugs I’d avoid them and just use a traditional plugs. It seems like every 5-6 years someone comes up with a new super plug or super spark plug wire. First it was capacitors in the wires and now they’re in the plugs. At the end of the day the only thing that matters is the material the plug is made out of and a good tip design that’s gapped properly. If you plan on leaving the plugs in again for 100k you had better opt for a platinum or Iridium plug as they are much more resistant to wear than a standard plug. Platinum plugs do not perform better than standard plugs-they just last longer. In fact platinum is not a great conductor of electricity-though it is durable. Iridium conducts well and wears even better than platinum but they cost quite a bit.

My final recommendation is this-find a quality independent mechanic and let him do the job for you. If you’re on a budget just do the plugs and have him look the wires over carefully. If the wires look suspect replace them. Figure on maybe $50 for a set of platinum plugs or the factory plugs plus whatever labor a shop needs. Good luck.

Thanks for the input, all. It’s a 5.3L V8, and as far as mileage, I still average 17 overall in 2WD. I was just questioning the overall need to change wires and plugs. While reading up on plugs, came across mixed anecdotes re: Pulstar. In ancient times, I was able to discern misfires, check gaps, etc. The reason for my questions is that I think I’ll be doing the plugs myself, and wondered whether to do the wires, too. I’ve had good luck with local GMC dealers for routine service, and since auto computerization have had bad luck with independents. I’m a religious attender to recommended maintenance, and, as I told GMC in 2001, will replace this truck when there’s a full size P/U or similar utility vehicle that gets 40 mpg hwy. I need to do occasional “unmaintained road” travel in the boonies in AZ, so prefer the 4WD.

Changing plugs is like changing oil.  You don't wait for a problem.  In fact waiting too long can cause problems with plugs (they don't like to come out after a long time and then getting them out can be expensive.

Maintenance is done when it is scheduled, plugs are maintenance.  Repairs are done when needed, often because someone did not do the maintenance and are usually far more expensive.  A check engine light is not designed to alert you to maintenance. 

Pulstar is a SCAM.

The spark plugs fire about 20 times a second for 100,000 miles,
they are probably too busy to tell the
computer that they need changed.

If your going to wait until there is a full sized P/U or SUV in 4WD that gets 40 MPG, I suggest you read the owner’s manual maintenance schedule with a magnifying glass. Because, buddy, it will be a LOOOOOONG time before you see 40 MPG in a truck like that. They are just barely getting the econo boxes to 40 MPG + with hybrid technology. You’ll probably see trucks with flux capacitors and nuclear power plants before then.

The Pulstar plugs have been heavily discussed in this forum. Use the search key for lots of valuable information.

Briefly, they won’t do anything special to help your car, and at $25/each they do make the seller of the plugs quite happy.

I’ve always been told to use whatever plugs came with the vehicle from the factory… that the engine is designed around the burn time, resistance and spark of the plugs. Wires will wear out before the plugs do, so you need a tune up… A tune requires factory plugs, good wires, fuel filter, and cap and rotor, if it has a distributor cap.
$500.00 seems alittle steep for a tune up to me.

Good luck getting the old ones out after ten years. Be very very careful. If you strip the threads it’ll be tow in to the garage to have the head repaired.

“Because, buddy, it will be a LOOOOOONG time before you see 40 MPG in a truck like that. They are just barely getting the econo boxes to 40 MPG + with hybrid technology. You’ll probably see trucks with flux capacitors and nuclear power plants before then.” BustedKnuckles, while I fear you’re right, I previously owned a 1992 Honda Civic VX 4cyl non-hybrid that was dependable, ran great, and got 55mpg hwy on regular gas. I think 40mpg overall, esp plug in hybrid, is not an unrealistic goal. I’ll be waiting!!

From what I saw with my car, I agree that the brand and type as originally supplied is best. My car was running fine at 107,000 miles when I finally replaced the plugs using the equivalent in another brand. For a few thousand miles my engine ran worse (missed a little but only occasionally) than before I changed the plugs but eventually cleared up. Do spark plugs have a break-in period? Possible in my view.

Use compressed air around the old plugs to clear debris before and after the old plugs are loosened. Mine came out with no difficulty on a car that was run in salt country. Use a tiny amount of antiseize compound on the new plug threads and adjust the installation torque down a few foot-pounds to avoid stripping.