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Spark Plugs

Curious as to what most GM owners replace their original AC Delco spark plugs with when its time for replacement. When my '98 Malibu, 3.1L, had

240k kms, I replaced all the spark plugs and plug wires. Now, it has 320k kms and had been driven on the highway daily since the replacement. I've had an intermitten mis-fire problem with the car and it wasn't until today that I realized I replaced the original AC Delcos with Bosch Platinums, the wires I believe were also lifetime warranty Boschs. Up until now, I had been thinking there was a problem with one of the coil packs, especially since the ignition module plate (the steel plate the coils mount to with the male terminals) had a stripped out hole. I figured that the stripped hole had been causing that one coil mounting bolt to move around, thus losing its ground and even put a nut on the bolt going thru the stripped hole to keep it secure. I found a replacement coil mounting plate for free, replaced it, and it still seemed to mis-fire every now and then. As well as this, I had 3 other coil packs that I aquired from my brother-in-laws' junked Lumina, that I kept switching out with my coils until the engine stopped mis-firing. When the inspection ran out, I stopped driving the car and took the plate off of it because it needed a front wheel hub, which I didn't have the money or time to replace. Soon after, it went up for sale.

The car has been sitting in my garage, un-driven but started every so often, since last September. Today when I moved it out of the garage, the engine light came on and I could tell the engine was mis-firing. I put the OBDII scanner on it and sure enough, #6 was the culprit. I've since ruled out the coil packs since the one that had the stripped hole, fired two other cylinders and not #6. So I decided to pull the #6 plug, the electrode was quite black, but cleaned up easily with a wire brush and contact cleaner. Put it back in, started the car, engine ran fine and no Check Engine light (mind you, I had cleared the code before pulling the plug when the light was on). I've since replaced the wheel hub/bearing and now, I'm wanting to get the car re-inspected for an easier sale. But, I don't want to take the car in for inspection and halfway there, have it start mis-firing, and then have it fail because the Check Engine light is on.

So what I want to know is, is there really that big of a difference from using AC Delco and different brand plugs, or are GM engines really that fussy that they need AC Delcos put back in them? Before I replaced the plugs, I don't recall having problems with mis-firing. And, I have used Bosch Platinums in the past on other vehicles (non-GM) and had no issues with them. But if I have to replace the Bosch plugs with AC Delcos, I will, even though, I nearly broke my wrist on the 3 back plugs last time, LOL.

Any advice or related experiences would be helpful here. Thanks, Sharky

Reply to
Sharky
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Bosch Plats and Bosch spark plug wires are both crap.

If the car ran OK with the original AC-Delcos that's what I'd use.

nate

Reply to
Nate Nagel

I have used every brand in the book, and have only had a problem once. This was a Bosch, by the way, and was cited as being a recommended replacement for the plug on my GM.

I put them in without looking too much, and the car ran like crap. When I pulled them back out, turned out the plug depth (threaded length) was totally different...much too short.

Other than that, every replacement spark plug I have ever used worked fine. Maybe that is a testament to the low level of refinement my GM cars had.

Reply to
HLS

Well, since I posted this, I have done some internet research and it seems the opinions on the Bosch plugs, especially on GM vehicles, is split 50/50. There are those who swear by Bosch and say they have never had any issues and then there are those that say the only way to go is with the factory AC Delco plugs, or a different brand. Now, having said that, I personally have used Bosch Platinums before, but only on Ford vehicles. On both of those, I never had any issues at all. So, approximately two years ago when I replaced the plugs in the Malibu and went into pick up new plugs at NAPA, I didn't think anything of it when they handed me 6 Bosch Platinum plugs as a replacement, seeing as how they've worked fine for me in the past. And, I probably didn't even realize what brand they had given me in the first place, because they usually don't sell crappy parts.

Long story short, I think I will shell out a few extra $$ and replace the spark plugs before I sell the car and put AC Delco platinums back in the engine.

Thanks for all of the replies thus far. Sharky

Reply to
Sharky

I've heard tell that Bosch Platinums are not good for high mileage and/or older cars, because they foul easily and never clean themselves. the regular copper core "supers" are fine, but the factory plugs on everything made in the last 10 years are probably platinums.

I have personally had bad experiences with Bosch plug wires, so I'm a little prejudiced against them as well. I'll still use the copper core "supers" in my old cars but other than that I'm off Bosch.

nate

Reply to
Nate Nagel

My Astro van ran great for 80,000 miles and still didn't miss when I changed plugs.

I wouldn't have put anything but the original type of plugs back in.

Reply to
Scott

I would only (and do only) use AC/Delco plugs and wires. The car was built with them, so it works best with them, IMHO. Any other time I used cheaper (or sometimes more expensive) spark plugs or wires, I encountered problems. IIRC, the 98 Malibu requires the platinum plugs, which are a bit more pricey, but they last a very long time. You can try Napa, but my local Napa doesn't carry the AC/Delco plugs for one of my cars, so I go to Canadian Tire, or even the Dealership. For my '97 Bonneville, they are around $11 (Canadian) a piece.

Reply to
80 Knight

AC or Autolite plugs are all I use in my vehicles. I've had good luck with Denso Iridium plugs in my bikes and snowmobiles. OEM or NAPA for wires. Bosch stuff is junk IMO, not the parts I use for something I'm gonna keep.

Reply to
Repairman

I respect your opinion. Our opinions are all that most of us have when it comes to quality matters of this type. We have discussed motor oil, filters, spark plugs, cables, tires, and a plethora of smaller items of which most of us have opinions.

I wish we had a place to go to get real, unbiased, data on this.

Reply to
HLS

| > I would only (and do only) use AC/Delco plugs and wires. The car was | > built with them, so it works best with them, IMHO. | | I respect your opinion. Our opinions are all that most of us have when it | comes | to quality matters of this type. We have discussed motor oil, filters, | spark plugs, | cables, tires, and a plethora of smaller items of which most of us have | opinions. | | I wish we had a place to go to get real, unbiased, data on this. | |

My mechanic always gives me his unbiased opinion- "If you want to waste your money on those platinum plugs, go ahead and buy them; but why didn't the manufacturer use them in the first place."

Reply to
Anyolmouse

Some of the manufactures do use them.

Reply to
80 Knight

That would be nice, but it's difficult to believe anything these days. Who knows what studies are performed correctly, or even "persuaded" to go a certain way.

Reply to
80 Knight

I'm not surprised that you'd use your good luck with sparkplugs to make a negative comment about GM products. You smell more like canuck every day. You're obviously just as big a fool.

Reply to
Dave

Here's some unbiased data for you. The OP got 240k km out of his AC's. Why in hell would he decide to try a different brand?

Reply to
Dave

That is his opinion, nothing more. There are even some Yugos still on the streets.

Nobody gives a shit if you want to use one sparkplug over another, but that is NOT objective data.

Reply to
HLS

Fuck you, idiot.

Highly refined cars, like Ferrari, Mercedes, etc, might need a highly refined plug.\ GM normally doesnt.

Eat shit and die, you prick

Reply to
HLS

In message , HLS writes

Such a nice friendly response, no wonder you're involved in wars world wide.

Reply to
Clive

I have never been involved in a world war, but I dont take trash from idiots. Are you next in line?

Reply to
HLS

In message , HLS writes

Do you always talk to yourself?

Reply to
Clive

Don't worry about HLS. He only called me a prick because that's the part of my body he's most familiar with.

Reply to
Dave

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