Spark plug opinions

Hi, I have a 96 Rodeo V6 3.2L 4X4 with 125,000 miles. I'm getting ready to replace the spark plugs, and I'm wanting to know what brands and types of plugs people with Rodeo's are using and like. Should I only stick with NGK or Denso? Should I go with platinum or iridium plugs (does that make much of a difference in an almost completely stock Rodeo engine)?

-Thanks in advance for any replies.

almost sure iridium will work fine the big thing is to stay away from BOSH platinums

I use Autolites in my 94, but I've heard people talk on this board about later Rodeo's absolutely needing NGK's or Nippondendo's. I don't remember the years. Just don't fall for those fakey Split Fire type gimmicks. They do nothing except cost you more money.


Hmm, now that I think of it, Autolites are made by the same company the makes Fram filters which are total, complete, utter crap. I think I'll be buying a different brand of plugs next time.

I run what is on sale and it doesn't care. I have changed plugs 3 or 4 times over 125k 94 v6 bought new. Never used platinum on this car or Bosch.

Thanks for the replies everybody.

So I neglected to check the forums here before jumping into replacing my spark plugs. I put in Bosch Platinums on a 98 V6. Just did this a few days ago. Should I go ahead and get rid of them and get NGKs or Densos? Why are Bosch platinums so bad?

I have Bosch platinums in mine, been there for 70k miles, I haven't had a single issue.

...Why are Bosch platinums so bad?

They are ok, but just don't work well in some applications. Year 2000 and up 3.2/3.5 don't work well with bosch, <2000 will be fine.

Joel

2000 Rodeo 3.2 114,000 miles...

Several months back I had a "just between you and I" conversation with the parts department manager / technician at my local Isuzu dealership regarding the need for Denso plugs for my rodeo . His advice - If you don't mind changing plugs every 30-40 thousand miles, the NGK or Bosh NON PLATINUM work perfectly and don't interfere with the sensor function of the plugs. I have been running NGKs for 4,000 miles now and have had no problems. I pulled a plug from each bank @ 2,500 for inspection and the color and condition was normal. I have seen no change in milage or performance.

Well I should be driving back to Austin today once I get my car out of the shop. Evidently i've been driving on a bad CV boot and two broken CV axles. So if I get any lights i'll let y'all know. I really don't want to have to change the plugs again, but if I need to i'll get the Densos/NGKs, whichever is easier to find.

..NGK or Bosh NON PLATINUM work perfectly and don't interfere with the sensor function of the plugs..

Good info! We are finally starting to collect some data as to other spark plugs that will work on the ion sensing equipped 3.2/3.5 (2000+). I'd rather run regular NGK's any day.
Keep us posted! :cheers:

Thanks
Joel

I put a set of Autolite platinums from Wal-Mart in my 01 Rodeo 3.2 4x4 and have been running them for about 6k without any problems at all.

The only thing platinum plugs are good for is lasting longer.

Yeah, I'm thinking about going with a different brand this time - my mechanic tends to lean towards Bosch products, but the more I read about their plugs, I'm not too happy.

I haven't had any problems, and yes the "Platinum" plugs have lasted quite a while, but if they're not all that great, I'm not gonna shell the $$$ either.

I was told by the mechanic that replaced my CV axles that the NGK/Denso plugs are prefered equipment in most japanese cars. Fords are really the only cars that like Bosch plugs with no problems. He also explained that the irridium plugs burn at a much higher temperature so you get a cleaner and more effecient burn. Though I've since found myself in the poor house after the CV axle business back at Christmas (I was straight up suckered into that one) I really don't see a need to drop $60 for a new set of plugs. Nothing seems to be wrong so far. But it is on my list of things to do to the car.

I'm running Champion single electrode platinums now. The V6 appreciated the changeout. I think I took out some cheap Autolites that were fine for 30K or so.

He also explained that the irridium plugs burn at a much higher temperature so you get a cleaner and more effecient burn.


This is complete and utter BS. A spark is a spark. Plugs are simply a way to get the spark from the outside of the engine to the inside. They cannot produce a hotter spark than whats already there.

This is complete and utter BS. A spark is a spark. Plugs are simply a way to get the spark from the outside of the engine to the inside. They cannot produce a hotter spark than whats already there.
Here's an interesting write up about Spark Plug Heat Range.

Heat Range
The operating temperature of a spark plug is the actual physical temperature at the tip of the spark plug within the running engine. This is determined by a number of factors, but primarily the actual temperature within the combustion chamber. There is no direct relationship between the actual operating temperature of the spark plug and spark voltage. However the level of torque currently being produced by the engine will strongly influence spark plug operating temperature because the maximum temperature and pressure occurs when the engine is operating near peak torque output (torque and RPM directly determine the power output). The temperature of the insulator responds to the thermal conditions it is exposed to in the combustion chamber but not vice versa. If the tip of the spark plug is too hot it can cause pre-ignition leading to detonation/knocking and damage may occur. If it is too cold, electrically conductive deposits may form on the insulator causing a loss of spark energy or the actual shorting-out of the spark current.

A spark plug is said to be "hot" if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be "cold" if it can conduct more heat out of the spark plug tip and lower the tip's temperature. Whether a spark plug is "hot" or "cold" is known as the heat range of the spark plug. The heat range of a spark plug is typically specified as a number, with some manufacturers using ascending numbers for hotter plugs and others doing the opposite, using descending numbers for hotter plugs.

The heat range of a spark plug (i.e. in scientific terms its thermal conductivity characteristics) is affected by the construction of the spark plug: the types of materials used, the length of insulator and the surface area of the plug exposed within the combustion chamber. For normal use, the selection of a spark plug heat range is a balance between keeping the tip hot enough at idle to prevent fouling and cold enough at maximum power to prevent pre-ignition leading to engine knocking. By examining "hotter" and "cooler" spark plugs of the same manufacturer side by side, the principle involved can be very clearly seen; the cooler plugs have more substantial ceramic insulators filling the gap between the center electrode and the shell, effectively carrying off the heat, while the hotter plugs have less ceramic material, so that the tip is more isolated from the body of the plug and retains heat better.

Heat from the combustion chamber escapes through the exhaust gases, the side walls of the cylinder and the spark plug itself. The heat range of a spark plug has only a minute effect on combustion chamber and overall engine temperature. A cold plug will not materially cool down an engine's running temperature. (Too hot of a plug may, however, indirectly lead to a runaway pre-ignition condition that can increase engine temperature.) Rather, the main effect of a "hot" or "cold" plug is to affect the temperature of the tip of the spark plug.

It was common before the modern era of computerized fuel injection to specify at least a couple of different heat ranges for plugs for an automobile engine; a hotter plug for cars which were mostly driven mildly around the city, and a colder plug for sustained high speed highway use. This practice has, however, largely become obsolete now that cars' fuel/air mixtures and cylinder temperatures are maintained within a narrow range, for purposes of limiting emissions. Racing engines, however, still benefit from picking a proper plug heat range. Very old racing engines will sometimes have two sets of plugs, one just for starting and another to be installed once the engine is warmed up, for actually driving the car.

And something about center Electrodes;

Center Electrode
The center electrode is connected to the terminal through an internal wire and commonly a ceramic series resistance to reduce emission of radio noise from the sparking. The tip can be made of a combination of copper, nickel-iron, chromium, or precious metals. The center electrode is usually the one designed to eject the electrons (the cathode) because it is the hottest (normally) part of the plug; it is easier to emit electrons from a hot surface, because of the same physical laws that increase emissions of vapor from hot surfaces. In addition, electrons are emitted where the electrical field strength is greatest; this is from wherever the radius of curvature of the surface is smallest, i.e. from a sharp point or edge rather than a flat surface. It would be easiest to pull electrons from a pointed electrode but a pointed electrode would erode after only a few seconds. Instead, the electrons emit from the sharp edges of the end of the electrode; as these edges erode, the spark becomes weaker and less reliable. At one time it was common to remove the spark plugs, clean deposits off the ends either manually or with specialized sandblasting equipment, and file the end of the electrode to restore the sharp edges, but this practice has become less frequent as spark plugs are now merely replaced, at much longer intervals. The development of precious metal high temperature electrodes (using metals such as yttrium, iridium, platinum, tungsten, or palladium, as well as the relatively prosaic silver or gold) allows the use of a smaller center wire, which has sharper edges but will not melt or corrode away. The smaller electrode also absorbs less heat from the spark and initial flame energy. At one point, Firestone marketed plugs with polonium in the tip, under the questionable theory that the radioactivity would ionize the air in the gap, easing spark formation.

ok so last year i was giving the big red machine a once over trying to cover every little base to get another year out of it and i went with the bosch platinums and didnt quite seem to be different i had pulled autolites from it boy were they a mess. i dont see where my milage went up or anything of the sorts and ive put over 20,000 on them i think next summer ill try something different just for the sake of testing...anything to keep the beast running!!! why do i love this truck so damn much???????

This is complete and utter BS. A spark is a spark. Plugs are simply a way to get the spark from the outside of the engine to the inside. They cannot produce a hotter spark than whats already there.

Iridium plugs are better at passing the 'spark' from the coil to the the tip then conventional plugs, therefore 'hotter spark'. As was pointed out in canuckleheads post, with conventional plugs the edges erode so the quality of the spark deteriorates (this is why denso came out with the 'U groove' for their plugs, more edges). Iridium, platinum, etc. also pass electrons easier.

One reason I like any denso plugs so much is they use better center cores then some other plugs so last longer and flow electons easier. This is a main problem I have seen with champions and bosch plugs, the center cores seem to go bad fairly quickly.

I use the stock replacement NGKs.