Bosch "double" Iridium/Platinum works fine in the Volvo, they are not picky.
But whatever you get, get pre-gapped.
But whatever you get, get pre-gapped.
What makes certain spark plugs not work in certain engines?
- Thread starter Chris142
- Start date
Different resistance in the plug or not exact heat range as OEM's
In my 1960's engines, the 400 in the 4-4-2 and the 427 in the Vette, love cheapo Autolites.
Everything else gets OE.
Everything else gets OE.
It's a gap issue here - the turbo VW EA888.3s can run multiple plugs, but at a 0.04+ gap, it's going to get mifires.
The manufacturer of the car didn't test and calibrate the ECU and engine with this plug, so they are going to be a "I don't know how it will work" category. It may work it may not, depends on how close it is to the factory plug in the combustion chamber. The engine may have some quirks that need a specific plug to work well or pass emission test for the duration of life it is spec for. More expensive isn't always better.
I think these posters are on to something. Maybe the cross referenced plugs aren't as "equivalent" as the factory specified plugs as we are lead to believe.
Piggybacking on my earlier comment, while BMW specifies both NGK and Bosch plugs, but they are specific models with BMW part numbers.
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- Apr 25, 2023
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Every MOPAR I've ever had or seen came with Champions, so that is what went back in.Its been like that since the 1960's, some how all the different spark plug manufactures for their brand of vehicles/ engines seem to work good in said brand. AC for GM, Autolite for ford, Bosch for German stuff, Champion - aircraft and sometimes other engines, NGK and Denso Japan stuff. Don't know what works ok in Mopar, was it Champion that supplied them?
I had a ford company truck that I ordered a tune up, mechanic used NGK plugs- what a disaster which also took out the cats. Changed to OE ford plugs and never had an issue after that.
My Honda may have Denso's and when the time comes I have a set of NGK Ruthenium I would like to try out but really should stay oe as there are no issues.
My old horse chev vortec 385 TPI just plains runs/idles better with NGK IX- there's no arguing with it after trying several different heat ranges and types.
My Honda may have Denso's and when the time comes I have a set of NGK Ruthenium I would like to try out but really should stay oe as there are no issues.
My old horse chev vortec 385 TPI just plains runs/idles better with NGK IX- there's no arguing with it after trying several different heat ranges and types.
And most important the characteristics of the insulator materials. That is likely the most secret of any plug manufacture.
Also the larger the gap, the easier to blow-out the spark.
I put Autolites in a friend 80's LeBaron (or whatever it was) 4 banger. Wouldn't run right. I asked her to take it to the dealer; I had no idea. They put Champions back in and all was good. I was blown away.
This is most likely the case. I experienced the same issue with different plug brands not working in some vehicles but great in others.
A plug can fit and have the same "specs/range" but there are differences beyond visual. For example, internal resistance on some plugs is via a resistor where as other plugs that resistance is via a air-gap within the insulator.
Alot of plug technology inside a plug that we can't see without either disassembly, reviewing the build plan at the factory or being the engineer of the plug
Stating the obvious?
Expanding on you adding more information on spark plug gap. Which I'd imagine you didn't believe was obvious to everyone either.
Good response. I was wondering what the heck..........
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Iron Harley Sportsters, shovel heads, all evolution 80”, RN12YC Champions. There was also an Autolite plug that ran well, but I don’t remember the number. Anything other than that, I’d get miss under load complaints. I agree, run what the OEM put in it. I put plugs in my Ford Fusion at 90,000mi and they were “copper”. They looked very good for their age. Replaced them with Motorcraft of the same type and my son has 150,000mi on the car. No misfires.
Back in the 90's. The little Subaru Impreza boxer engines from Japan came with U.S.A. Champions in an odd heatrange (#8)
Wife drove these things. Ran good. They also used U.S.A. sourced Packard ignition wire (the best).
At 30K mile change time, tried equivalent NGK, and it ran poorly. Put the old Champs back in and motored on.
That's a pretty hot plug for an AC motor. That would be the #65 Autolite
Ran #63 heatrange with good luck in little Mitsubishi and other Japanese cars that asked for a RN9YC Champ
Champs and Autolite = two very good One dollar sparkers.
- Arco.
Some engines are picky about plugs but others will happily fire pretty much anything you can screw into the hole. Toyota's like Denso or NGK. Not much anything else. You are always safe using whatever it came with originally. Given how long they last it doesnt pay to cheap out.
Paco
Paco