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What's the difference in Bosch W7DC and WR7DC plugs?


ClayW

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You don't want the "R" by the way. Unless you're running a very specific EFI.

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As well as reducing electrical noise for radio, television and mobile telephones etc, many modern ignition systems require resistor plugs to stop electrical noise from interfering with the vehicle's on-board electronic control units (ECUs). If non-resistor plugs are used in place of resistor ones, the result can be malfunction and in some cases immobilisation of the vehicle. Resistor spark plugs should always be fitted, therefore, where specified. NGK resistor spark plugs contain a single ceramic monolythic resistor of approximately 5000 ohms.

From NGK website.

Originally I thought they were to keep from interfering with your old skool am radio.

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' 02 plug connectors contain the resistors. You do not want to use WR plugs in any ' 02 that does not have the mods to except them. I've been running W8DC in all 3 of our daily drivers for about the last 15 yrs. and they perform perfectly, asuming all other aspects are within prescribed perameters. Currently cost $1.38 ea. @ BMP stores. I change mine every 12K miles, whether they need it or not. For six bucks it ain't gonna break the bank.

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Yeah, I change mine everytime they're out.....which, since my current motor burns oil, is sometimes once every couple of months! It just seems so much easier to replace them than to clean them. Since they cost so little, why not, huh?

ClayW
1967 1600-2 - M42 - 1521145          Follow my project at www.TX02.blogspot.com          E30 DD Project Blog

 

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I'm surprised to see you running an 8. That's a pretty cold plug. Usually 2002 spec is a 6 or even 5. Hmmmm inquiring minds want to know...

Personally I run NGK BPR6es in the summer and BPR5es in the winter time. Although with the new motor I may only run 6's we'll see...

-------------

BigDog

'76 2002

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I'm surprised to see you running an 8. That's a pretty cold plug. Usually 2002 spec is a 6 or even 5. Hmmmm inquiring minds want to know...

Personally I run NGK BPR6es in the summer and BPR5es in the winter time. Although with the new motor I may only run 6's we'll see...

In Bosch land the higher the number the hotter the plug i.e. 7 is normal and 8 is hotter.

But it is the reverse for NGK i.e. 6 is normal and 5 is hotter.

I use 8's in my oil burning 02 to stop them fouling so much. Beaner7102

1971 - 2002 RHD VIN 1653940. Agave (stock with Pertronix & 32/36 Weber) - "Cactus"

1972 - 1602 RHD VIN 1554408. Fjord (with 2L motor, 5spd & LSD - Weber 40/40 to come) - "Bluey"

1984 - E30 318i VIN WBAAK320208722176 - stock daily driver

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