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Spark Plug Gapping & Which One's

FJH97XJ

NAXJA Forum User
I would like to know what you folks are using as far as plugs go. Right now i'm using Bosch Platinum +4 that cant be gaped w/ an Accell 300+ Ignition, Accell Super Coil & MSD 8.5 Super Conductor wires. I've used NGK V-Groove that I gapped to .050 & had good results also. I ask this because I had my check engine light come on about a week ago & when I retreved the codes one of them was a misfire in one of the cyl. . I think thats showing up because of the ignition. Does gapping larger really make that much of a difference? Please help. Thanks
 
You should just buy factory champions andgap them to the Emissions sticker on the underside of the hood or on the firewall.Whenever you gap larger you decrease the duration of the spark and just make it "hotter". If you gap smaller like (.035) its easier for the electricity to "ionize the air gap" (spark) and it will actually last a little longer. I have seen plenty of Jeeps with newer 4.0's come in to the dealership with a misfire code and brand new Bosch plugs .When switched back to factory Champions they ran great and the misfire code did not return. the only real reason that manufacturers are using platinum plugs is that last a lot longer than standard tipped plugs, (because platinum is harder)to meet Federal Emissions Waranty standards.What were the other codes in the PCM?
 
I had a truly aweful experience with the Bosch platiums in my wife's Saturn. She insisted on the "fancy" plugs. The thing would stall on the the highway at 60mph!!!. I went back to the AC Delcos it had and no probs since....
 
I just had a check engine light come on yesterday and I have Bosch Plats that have been in about 6 months. I had already bought a set of OEM plugs to replace them. I guess I'll replace the plugs and then go and have the codes read to see if that was it. I can't find anything else that would cause the light. I have a 99 sport with only 32K.
 
Bosch 4+ plugs... I have put those in almost a year ago and they seem to be doing pretty good. I drive about 120 miles each day and my mileage seems to have imrpoved after putting those plugs in. Also I have never had a stalling problem.... are you sure you got the right ones in there? How do they look when you pull them out?

Kejtar
 
Yeah I would still Gap the plugs to factory specs. I mean, the factory coil is probably good for about about 80,000 volts tops even though the most it will ever actually take to ionize the air gap is like 20,000.So even though the factory coil could make probably 80k volts, it only takes a fraction of that to jump the gap, so the rest of the electricity , being lazy and taking the easiest path, just oscillates back and forth in the wire and dissipates. The only real advantage then, that aftermarket ignitions have is providing longer spark duration or a few short quick sparks like MSD(Multiple Spark Discharge). Gapping at smaller gaps is just another way to make the spark longer in duration because it helps encourage all that lazy oscillating electricity across the gap. So after some long rambling about ignition systems that nobody asked for, Id just say put in some Champs, gap em to .035" and see where that gets ya. -Aaron
 
I'll throw in another vote for Champions gapped to .035 (I think that's the factory setting). 130k on my 96 4.0 and it's running strong with these plugs.
 
To throw in another comment, I generally buy OEM from the dealer, hey it always works and I know it's going to fit. I bought 5 champions from the dealer, he was out and these were the last he had in stock so I stopped at a local auto store and picked up one more, same model. Got home, pulled em out to gap em and guess what...the one from the parts store was different, thinner electrode and thinner ceramic on the business end. Since then I always get the dealer supplied ones.
 
I agree, that typically AMC/chrysler motors don't typically respond as well to the bosch platinums. It seems like chevy motors really like them though, plenty of Dyno testing to support it. I really don't see the harm in going with platinum, but the plus 2's and plus 4's are sort of unnecessary. Granted I run the 4's in my LT1,but I got a deal on them and was curious. I really don't like that you can't change the gap. Unless, you are running a stock engine, there is some tuning that can be done with plug gaps. Just like everything one person will have good results with a plug or a certain gap and someone else will not. You really just have to see what works with your engine and mods. Champions typically work well, but so do NGK, Bosch, Autolite, etc.
JMTC
Dustin
 
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