83TransAm

A couple of days ago, I started having some HORRIBLE misfiring. I took my car to one of my friends and he suggested that the distributor was bad or that my timing was off. So then I took it to my uncle who is a master mechanic and work at Ford for 20+ years and here's how the conversation went (more or less):

Uncle: Wow, that thing is misfiring like a mother@#*%!
Me: I know. What do you think it is? Distributor?
Uncle: Spark plugs.
Me: Can't be. I just replaced my spark plugs 2 months ago.
Uncle: Well it is. Trust me.
Me: I really don't think it is.
Uncle: What kind of spark plugs did you use?
Me: Bosch Platinum 2's.
Uncle: (hysterial laughter followed by disapproving head shaking)
Me: What!?!
Uncle: Go get some REAL spark plugs and come back here.

So I go up to the store and get a set of Champion spark plugs (AC Delco's were all sold out). I get back, and sure enough, as I was pulling out the Bosch Platinum 2's, 3 of them were fouled after only 2 months of use. My uncle then told me to buy the OEM brand of plugs because they were MADE for my type of engine. To make matters worse, after I started up my car with my new plugs, gas comes backfiring out of my carburetor from all the built up gas. So now I have to rebuilt my carb.

Has anyone had similar experiences? I did not know specific spark plugs were so important for specific cars. I'm sure never buying Bosch products again!

Jokerman

From owning a bmw i can say that bosch in my exsperiance has made some very high quality products although the 2+ that you got i believe are like split tips or something, anyway no one thinks much of them. I never had problems with my bosch plugs fouling, missfireing, or prematurly failing on my bmw which wound much higher than our engines will (able to repeatedly rev to over 6k, peak power and tork at 5500). Never get gimmicky plugs, no matter what company makes them they always suck, just get your standard spark plug from a company of your choice and you will be set.

Slade1

The ac delcos are probably the best set of plugs for most applications of thirdgen... once you make more power and send the engine into the 5k-6k powerband or higher, then a plug change may be required, till then the delcos are pretty good and most on the board swear by them.

formul8!!

I have been using Bosch platinums in my L98 for more than 5 years. No problems with them at all. Just don't run them with nitrous.

soulbounder

+4s were in the car when I bought it. They ran fine. Switched to AC Delco when I did a tune up. Didn't notice any differences. Did another tune-up about 20K miles later trying to solve a problem. Used the +4s again. They are still running fine. (No, I didn't buy them, I won them through a contest. No way I'll spend $5.99 a plug.)

91-Z-Speed

I just installed a set of +4's in mine and it made a heck of a difference. I switched from Delco's. I gained 4 h.p. and 6 lb ft of torque, and ive been happy ever since

mechanicalmehem

just so you know if you ever take your car to a dealer with a miss/rough idle and have bosch anything in it they WILL tell you that they have to start by replacing them first, bosch and chevy/gmc dont go together!

lock

Been running Bosch Platinums for 10+ years in my chevys... shrug. Id say if your fouling plugs of any type, you have some other problem unless the plugs jsut arent hot enough.

ronterry

Champion are fine. Gap those suckers with Jacobs pliers, file them back a little. You've got a plug that will blow any gimmick plug away.

BTW: That fouling could have been a wrong heat range. I mean every brand of plug is going to have it's own characteristic, so heat range number don't just cross over very good.

Ron

IROCmonkey

quote: just so you know if you ever take your car to a dealer with a miss/rough idle and have bosch anything in it they WILL tell you that they have to start by replacing them first, bosch and chevy/gmc dont go together! -------

hmmm I guess if I ever take my TPI to a dealer they'll have to tell me to take out my MAF sensor and all eight injectors, along with my plugs

Seriously, I've used standard Bosch platinums for quite sometime, I have found them to last much better than champions or autolites...I've also been quite happy with the AC Delco Platinums

DSaylor

I've never used the platinum 2's or 4's, but my experience with the regular bosch supers and the platinums is that they're a shorter(colder) plug and they will foul in alot of engines, mine included.

Some engines can get by with a colder plug, and some cant. My old 305 had a valve seal leaking on one cylinder and with the bosch's I had to change that plug everytime I drove it, Delco's would last about 2 weeks.

iroc22

I ran Bosch Platinum plugs in my car for awhile and they just fouled up after about 8 months of use. Went to regular AC Delco's and I have been happy with them since. Platinum doesn't conduct as well as copper.

86SCBNJ

I have been running Bosch plugs for years in different makes and models with no prblems what so ever. They fit great with the headers, since they are shorter than the ac/delco's and they last a long time....

vic_V8

a year ago I bought spiltfires, didn't even fire, returned them b@starts and got plain old delcos, flooded the engine in the winter and car hasn't run the same since, so I bought so delco rapid fires yesterday

87IROC350

I ran a set on a stock engine with no problems. They last forever but for performance mods AC Delco is the way to go.

Fast3rdGen

lol tell that to all these people that buy a new toyota land cruiser(V8) or corolla and have to have irridium tipped plugs at $19.00 a pop! (i work in a toyota parts department)

Andrew H

I installed the Bosch +4s about a month ago and ever since then, I've been convinced that (although the car was running a bit smoother to start with) there's been less power -making a lot of noise and going nowhere! -more recently though, the last week or so, it's been misfiring (only when I push it hard -because it's getting less and less responsive) I'm convinced it's the plugs as that's the only thing that's been changed and some kind of deposit must be building up -they're probably great for german cars, but just don't seem to agree with mine (5L TPI). -I might even take advantage of the bosch money back guarantee as I'm not that impressed to be honest!

I had basic Champions in there before, which seemed pretty much the same as the NGKs before that. I want to avoid platinums now I think, but is there an upgrade compatible plug (with an adjustable electrode) that anyone can recommend for me for that car (or should I stick with the basic one) as well as some good replacement leads that I'll do at the same time -my sister's in the US at the moment so I'll keep her busy and get her to bring me the stuff back!

91rsjamie

My car had Ac Delco's in it when I got it and it ran ok to good. But then I did a complete tune up and put bosch +2's, Accel 8mm wires, MSD coil and Accel cap and rotor and it made a hell of a difference. Runs better on cold starts and twice as good while hot!

Hg

Just wondering, what brand are they? NGK or the Densos? I really want to try some of the denso iridiums, but they are $$$!

TonyZ83

I can't stand Bosch parts! I had a brand new set of their $50 wires for a Maxima fall apart on me before, and recently on my 79 T/A, I had a set of wires go up in flames, almost igniting a fuel line and blowing up my car! The T/A also had Bosch platinum plugs in them that the previous owner had put in a few months before and when I got new wires after the fire, I checked the plugs. The were already fouled out! I swapped in some AC Delco plugs, and it runs a lot better now.

DSaylor

Another thought,
Most serious racers at the track spend alot of time indexing plugs, and cutting back the ground straps to put the spark in the path of the incoming air/fuel charge.
The bosch +2/4's have to be a terrible plug from this standpoint.

badgta

iTrader: (4)

i used to have ac delco rapifire2 plugs in my l98......

after about a year they turned red!!! i don't mean they were hot, when you pull them out they were red!!!

i shortly put nitrous on and after i would get done i would have a miss from hell!!

i now have the bosch platinum plugs for my 500hp nitrous fed beast thats going to be done in about 2 months.... i hope them and the msd6a go good together with n20

bandit454

All dealer mechanics will tell you that Bosch are crap and need changing to original, they are trained that way. They are not going to recommend something they don't sell. Cars will take any brand spark plug if they are the right type. I have used them all, use Bosch Platinum Plus 4 now and never had a problem. Champion have always been crap on my end, AC Delco are ok. I only use Bosch now because I have NEVER had a problem out of them. Find what you like and if your car is tuned right it should not be fouling plugs often. You may get a bad one every now and then but not often. Thats my two cents worth.....

Grim Reaper

Sounds like you found the REAL source of the problem. The fouled spark plugs are just a symptom.

I've ran all types and currently use Bosche (because they are shorter and clear the headers on my car). They are no worse than the AC Delco's. Mine NEVER foul, have a nice "tan" look and I routinely get a whole year out of them. But my car is perfectly tuned - including the eprom.

It's not the plugs, it's your carb.

OzzMaro

QUOTE: --
"But then I did a complete tune up and put bosch +2's, Accel 8mm wires,"

Hm, a bit off the topic, but I was running a set of Accel 8mm's for about two weeks and couldn't figure out why the car whould shudder sometimes for no reason. Just wondering if anyone else has gone at them with an ohm meter? Did that to mine (should have done that in the first place). A few ranged around 10k ohm's EEK!; and two of them wayy past 30k ohm's.

Grabed a few stock cables that I was running, and they raged from 680ohm's - 1800. Hm, odd. I even took a uncut Accel 8mm cable and tested it. At 3' it ranged about 35k ohm's. Oh well. Went out and grabed a set of MSD 8.8's (uncut) and tested one of them on the meter. Whooo... nice, 3.5' ranged about 135ohm's.

Basically mentioned this, because a lot of people cut their own cables, but I don't know how many people take an ohm meter to them. Those accel's were supposed to be HEI compatible, I mean, for HEI (which needs to be in the hot cable range, I believe?), I think 10k ohm or even 30k + is eeesh!

-Dan

Fast3rdGen

toyota plugs are manufactured by denso.

DakotaSLT

Here's a question for you guys with Bosch Platinums: they make plugs for our cars in aluminum and iron, which would you prefer?

91-Z-Speed

I would prefer aluminum, because of its lighter weight, but i would want an aluminum block and cylinder heads too

83TransAm

Is 18 ounces really going to make that much of a difference? Lighter weight, lol, spark plugs are so miniscule in weight that it's almost ridiculous. I'm going to go take a few ***** off my stereo now because they are taking up too much weight, lol.

Steve

91-Z-Speed

i said aluminum, yes for its weight difference, but i also like it because of it's easier ability to heat up and making air burn easier and faster

Ace911emt

Bosch platinum almost wrecked my engine Ceramic center destroyed on 4 of 8 plugs 🤬

89Warbird

I ran Bosch Platinum +4's in my GTA for over 20 years and they worked great! This was while the engine was stock and then heavily modified. I am now installing a 408 CID 750 HP LSX and I'm going to give e3 spark plugs a try. I'll find out on the dyno if the e3's are any good.

clubber

iTrader: (1)

Lots of twenty year necro threads coming back lately. Kind of weird. On this plug subject, In a test sampling of one old Mazda truck, it ran better on 40K old autolites than Bosch's. I know it doesn't make sense but it was so. I've never used Bosch since and never had a plug related issue since. That was 30 years ago though, longer than this thread even.

mikeceli

iTrader: (2)

I was working in the Auto Repair Business , back in the 70's-80's and I recall when Bosch Platinum plugs first came out. They had a tendency to foul, especially on engines running less than perfectly.

Drew

iTrader: (58)

I've been on this forum since 1996. In all these years, I've read so many stupid statements, I can't begin to recall most of them. However, I'm pretty sure this is the stupidest most ignorant thing I've ever read on this forum, or any other for that matter.

The question being asked is if the CYLINDER HEADS are aluminum or cast iron, not the spark plugs. This is an artifact of old bad documentation that believed aluminum heads were available on a thirdgen. Probably someone copied/pasted something from the Corvette column to the Camaro column on accident. Similar to how every auto parts source on the planet shows a serpentine belt pulley on AC compressors for 87 Camaros.

Komet

The ceramic exploded on the Bosch Silvers in my last car. Cost me a few grand on the sale when the guy had a pre-purchase inspection done and they found scratches on the cylinder walls.

I mean, I wasn't not bouncing it off redline from time to time, but they only had 11k miles on them.

midias

Never tried bosch in my TA but I did try them in my accord and Solara. Both hated the +4s went back to NGK and life was good. I know Audi guys love them

DynoDave43

iTrader: (11)

This is funny because I had the exact opposite results. I usually run what the factory specifies, and don't look back. In this case, 1986 Dodge Omni with carb'd 2.2L four, it idled in open loop. And idling in gear warmed up, it would drop a cylinder every now and then and fairly regularly. No other symptoms, and kind of "normal" for that engine. Nothing more than changing to Bosch platinums solved this problem. So I think they have their place.

TTOP350

iTrader: (8)

To the fella that said champions are good 20yrs ago, they are good, for some lawn mowers and trashcan filler.

Arctic White 91 RS

My experience with spark plugs over 389,500 miles in my 91 RS Camaro w/305 TBI A4 was the recommended AC Delco's were good for about ~25,000 to 30,000 miles them the highway mpg started to drop off. Car would run OK but not excel at mpg unless car got fresh plugs.

Switched to Bosch platinum and ran them exclusively for ~250,000+ miles. Could get ~50,000+ miles without issue. The Bosch platinum, +2 & +4 ran etc perfectly well, zero issues.

Best highway gas mileage with AC Delco was 29.5 mpg when car was brand new.

Best highway gas mileage was with Bosch plugs was 33.5+ mpg when car was well broken in, new distributor, fresh coil, new plug wires, running 93 octane, all synthetics in driveline, fresh alignment, full inflated tires etc ie dialed in for mpg. GPS confirmed mpg.

Later had a 91 RS Convertible and that car also seemed to run slightly better with Bosch platinum's than AC Delco's. Although the new coil, cap, button, rotor & wires also helped.

IMO, Champion plugs = garbage 🗑, maybe OK for lawn mower maybe not.

Will take NGK every time over AC DelcoI don't like AC Delco spark plugs. None of my current four GM cars run AC Delco. It's all NGK in the LS cars 91 RS, 99 T/A, 02 Z28 and the 72 vette has Autolite racing plugs in the Dart 400. My 99 T/A even came from the factory with NGK platinum's...lol

Several times it was pretty hilarious seeing a know it all at NAPA or AutoZone have a melt down/blow a gasket over purchases of "German: Bosch plugs or "Japanese" NGK plugs for my GM cars and not "Merican" AC Delco.

TTOP350

iTrader: (8)

NGK and Delco are made on the same line. I've pulled original plugs out of LS engines that have ngk and delco printed on the same plug.