Spark plugs - Nickel vs Platinum vs Iridium
Discussion
Interested in others opinions on how these longer lasting plugs perform particularly in respect to possibly causing slight misfires?
I think I seem to have established thar Iriidum can cause misfires in various engines, whitch is my experience, and only work well in a narrow range of engines. However don't know wheather Platinum have a propensity to also do the same. Then what about Nickel, particularly thinking about ther Denso TT range.
I think I seem to have established thar Iriidum can cause misfires in various engines, whitch is my experience, and only work well in a narrow range of engines. However don't know wheather Platinum have a propensity to also do the same. Then what about Nickel, particularly thinking about ther Denso TT range.
NickCLotus said:
Interested in others opinions on how these longer lasting plugs perform particularly in respect to possibly causing slight misfires?
I think I seem to have established thar Iriidum can cause misfires in various engines, whitch is my experience, and only work well in a narrow range of engines. However don't know wheather Platinum have a propensity to also do the same. Then what about Nickel, particularly thinking about ther Denso TT range.
Would be curious to learn more about how this was established, and what engines they allegedly do / don't work in. Not something I've heard of. Do the iridium plugs come gapped to the correct spec...?I think I seem to have established thar Iriidum can cause misfires in various engines, whitch is my experience, and only work well in a narrow range of engines. However don't know wheather Platinum have a propensity to also do the same. Then what about Nickel, particularly thinking about ther Denso TT range.
Unless the spark plugs are particularly awkward to get to (Subaru boxer engine for example), I've personally just used copper plugs, buy a load at a time (last time bought 24 NGK plugs for £56 delivered) and replace them every 2 - 3 years
NickCLotus said:
Interested in others opinions on how these longer lasting plugs perform particularly in respect to possibly causing slight misfires?
I think I seem to have established thar Iriidum can cause misfires in various engines, whitch is my experience, and only work well in a narrow range of engines. However don't know wheather Platinum have a propensity to also do the same. Then what about Nickel, particularly thinking about ther Denso TT range.
Nope, never had such issues.I think I seem to have established thar Iriidum can cause misfires in various engines, whitch is my experience, and only work well in a narrow range of engines. However don't know wheather Platinum have a propensity to also do the same. Then what about Nickel, particularly thinking about ther Denso TT range.
pretty much all modern cars have precious metal plugs due to their longer life and better overall performance.
Exactly what engine ?
NickCLotus said:
Engine is Peugeot JP5TU4 (NFU).
Iridium plugs caused slight misfire at idle and misfire at low throttle openings under load. Swapped them out and those problems went away. However now have slight misfire on partial overrun when hot, thinking it could be plug related again.
It would seem you have another problem if the plugs are installed correctly.Iridium plugs caused slight misfire at idle and misfire at low throttle openings under load. Swapped them out and those problems went away. However now have slight misfire on partial overrun when hot, thinking it could be plug related again.
And on the overrun, cars do a complete fuel shutdown, so you could not have a misfire, because there is nothing to fire.
Has this vehicle ever ran correctly ?
stevieturbo said:
It would seem you have another problem if the plugs are installed correctly.
And on the overrun, cars do a complete fuel shutdown, so you could not have a misfire, because there is nothing to fire.
Has this vehicle ever ran correctly ?
Well I believe it did when it had the original old plugs in it; these were Bosch FR8SC+ which is actually the wrong heat range for the engine which shouid be 7 by the manual,And on the overrun, cars do a complete fuel shutdown, so you could not have a misfire, because there is nothing to fire.
Has this vehicle ever ran correctly ?
Interesting that the misfires you're chasing all occurred under light load / no load conditions, when it's easiest to strike a spark. The exotic metal plugs also tend to use smaller electrodes which make it easier to strike a spark. If you're concluding that this is leading to a weaker spark then you've got an uphill job to prove that. Isn't it more likely that you're running the plugs too cold, or have a mixture or timing problem under those conditions?
GreenV8S said:
Interesting that the misfires you're chasing all occurred under light load / no load conditions, when it's easiest to strike a spark. The exotic metal plugs also tend to use smaller electrodes which make it easier to strike a spark. If you're concluding that this is leading to a weaker spark then you've got an uphill job to prove that. Isn't it more likely that you're running the plugs too cold, or have a mixture or timing problem under those conditions?
Well you could be right but funny how the misfire has changed from being at idle/low speed to on the overrun and the only change has been the plugs. In fact when I was trying to chase down the idle/low-load misfire I seem to recall that I found changing the plug gap helped/hindered the problem but can't remember which way around it was.That initial misfire was definitely related to the Iridium plugs; I swapped them in/out a few times to confirm.Those Iridium plugs were actually supposedly slightly hotter than recommended: NGK Iridium ILFR6B, equavalent to Bosch heat range: 6/7 as opposed to original spec acording to Haynes manual of 5. However the plugs in there when I got the car were Bosch FR8SC+ which is an even higher heat plug of 8 on the Bosch scale.
The downside of long life spark plugs, especially when access is difficult, is that the nightmare of a stuck solid plug that snaps in place is umpteen times the cost trouble and downtime that more frequent changes would have been.
I have the T shirt, engine out head removed specialist engineering shop remove plug and fit helicoil, lucky to get away with £1000 the whole job.
I'd paid for new plugs to be fitted before but obviously weren't, garage shut up shop in the meantime not as i could have proved anything anyway.
Won't get caught again, just as with oil changes DIY so you know its done and half or less the official service intervals.
I have the T shirt, engine out head removed specialist engineering shop remove plug and fit helicoil, lucky to get away with £1000 the whole job.
I'd paid for new plugs to be fitted before but obviously weren't, garage shut up shop in the meantime not as i could have proved anything anyway.
Won't get caught again, just as with oil changes DIY so you know its done and half or less the official service intervals.
The only way this adds-up is if the plug manufacturer equivalent heat range tables are not correct:
It feels as if the NGK Iridium ILFR6B (Bosch heat range: 6/7) were too cold causing issues at low speed, whereas the Denso KH16TT (Bosch heat range: 8) feel like they are too hot hence problems at higher revs,
Don't know whether to try a set of Denso KH20TT or even KH22TT (bosch heat range: 5, as per original spec) next.?
It feels as if the NGK Iridium ILFR6B (Bosch heat range: 6/7) were too cold causing issues at low speed, whereas the Denso KH16TT (Bosch heat range: 8) feel like they are too hot hence problems at higher revs,
Don't know whether to try a set of Denso KH20TT or even KH22TT (bosch heat range: 5, as per original spec) next.?
Tony1963 said:
This feels like you re trying to mask the cause by changing plugs.
As mentioned above, how can you have a misfire on the overrun? There s something not right about that.
He did say "partial overrun", although still odd.As mentioned above, how can you have a misfire on the overrun? There s something not right about that.
I think he needs to try another 4 sets of plugs first, before trying to diagnose the actual problem
stevieturbo said:
He did say "partial overrun", although still odd.
I think he needs to try another 4 sets of plugs first, before trying to diagnose the actual problem
Exactly, only on a slight downhill, one particular piece of road where it is always obvious and annoying.I think he needs to try another 4 sets of plugs first, before trying to diagnose the actual problem
When I had the low-speed & idle misfire I tried cleaning / testing / changing various items before I realised it was the pluigs causing it which is why I keep getting back to them as a possible source for the current problem. That and the fact that various sources seem to quote different heat ranges of plugs for this particular engine.
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