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I know the cost differince is almost double for the Iridium, but with the 3.2 using the spark plugs for sensing in the combustion chamber wouldnt Iridium be far better than platinum?? the heat and electrial properties of Iridium are much better than platinum. I guess the real question is, will I notice any differnce for double the money? (7 bucks ea for plat. 12 bucks for Iridium) EZ
 

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I hate to sound like a frumpy old lady. But you'll probably get the best performance with the oem spec plugs mentioned in your owners manual if you have a stock ignition.
 

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Ditto the stick with the factory setup. The ion sensing system was designed with the OEM plugs in mind. Thus, even if the iridium plugs did "work better" the Isuzu computer can't recognize the different electrical readings. Kind of like DVDs work better than VCR tapes. However if you shove a DVD in your VCR player you are just asking for trouble.
 

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i'm going to try and find out what spark plugs i have. I think i have bosch platinum that really really seems to work well. Once i installed them my mpg went up by 1 mpg average. Doesn't sound like much but over the past 40,000 miles i'm sure it is helpful.
 

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hadji_85 said:
i'm going to try and find out what spark plugs i have. I think i have bosch platinum that really really seems to work well. Once i installed them my mpg went up by 1 mpg average. Doesn't sound like much but over the past 40,000 miles i'm sure it is helpful.
Definately pull one to see what you have! Every report I've seen is bosch plugs cause nothing but problems on the 2000+ 3.2L's. It would be awesome to have a viable alternative to the denso PK16PR11 plugs.
G/luck
Joel
 

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Based on my limited reading, the ion sensing system works by feeding a current through the factory plugs. The computer then reads the electrical resistance of this current. In turn the computer uses its stored charts to convert those resistance readings to gas compositions. Based on the gas compositions the computer adjusts the cylinder firing. So if you change the electrical properties of the plugs the computer thinks the gas compostion in the combustion chamber has changed. It will then tweak the cylinder firing to try and get the gas compositions (i.e. plug resisitance) back into spec. Again if you put in different plugs you will fool the computer into thinking the cylinders are not working properly.

Again, just because the plug is "better" in theory doesn't mean it will work better with the rest of the engine management system. If you don't believe me do a search and note all the people who had problems changing plugs in these engines.
 

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tomster- that's been my understanding of the ion sensing system as well. Thing is, the 'computer' should be able to compensate and re-adjust itself with new (different manufacturer) plugs, but it just cant seem to cope :( . Yet another one of GM/Delphi's testing/dumping grounds. This has got to be the only truck in existance where you can only use ONE make/model of spark plug. Maybe two, if you count the few ion sensing models that came with champions.
G/luck
Joel
 

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JTK I don't think the ECU is that smart. I suspect all it knows is that it wants to control/fire to a certain ohm value during the ion sensing voltage pulse. It isn't sensing instantaneous cylinder gas compositions. That work was likely done by GM in a lab. They found the target gas compositions they wanted. They noted what ohm reading that occured at using presumably only the specified spark plugs. Then they pre-programmed that number into the ECU. Thus if you change the plug type (i.e. starting plug resistance) you change when the computer thinks the cylinder should be fired. Again, the ECM is only smart enough to know what the engine electrical readings are. Any change to the inherent plug resistance and the system is compromised. Again just my take and I am certainly no expert in this system so I could no doubt be wrong.

As to when Isuzu went to ion-sensing, IIRC that happened in 2001. 96rodeo you don't have to worry about this. You only have the typical match the plug for your engine concerns (e.g. right dimensions, heat range, gap, etc.).
 

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My issue here is not the tip of the plug. It is the electircal characteristics
INSIDE the plug. Ever plug has a different resistance. The resistance is
there to supress noise and electrical interfearance.

I do assume that one of the specks that companies comply to is the
resistance, but nontheless, the construction is different then stock
which might alter the "Sensor" characteristics.

BUT, I seriously doubt that the compensation the ION sensing system
makes for the timing and/or Air fuel mixture is in any way significant to
make any noticeable difference whatsoever in performance. IMO you would never no if the system was on, off, broke or working 100% if not
for a check engine light.
 

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timrkopi said:
..BUT, I seriously doubt that the compensation the ION sensing system makes for the timing and/or Air fuel mixture is in any way significant to make any noticeable difference whatsoever in performance. IMO you would never no if the system was on, off, broke or working 100% if not for a check engine light.
Yep, as far as I know, the ION sensing system will set a manufacturer specific OBDII code and generate random misfires (flashing CEL). When the ion system goes belly-up or does not like the plugs. IIRC- you will get serious bouts of power loss with the 'random misfiring', if it's real or not :shock: . Something that's not clear to me is- is it the ion system that tells the ECM exactly which cylinder is misfiring? More and more cars these days can tell you EXACTLY which cylinder is misfiring!?!? This hi-tech black-box stuff is WAAAY over my head :oops: .
G/luck
Joel
 

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Timrkopi, you seem to think the ion system is there to fine tune some inherent ignition system. I on the otherhand think the ion sensing system is the ignition system. You cannot just compromise it and expect the system to work fine (i.e default to some inherent/backup system). But as already noted I have no great credentials to support this theory just my take of the numerous posts I have read through the years about problems with any but the OEM plugs in these ion sensing engines.

While I wish you good luck, I still say you will spend a bunch of money for plugs that just don't work right in this application.
 
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