'87-'90 Renix 4.0; What plugs are you using?

[Ecomike]

Did you notice I got "top billing"?

LOL, I see that!!!! Guess I need work harder, LOL!

 

[gajeepguy]

Bosch SuperPlus copper core
OEM heat range.

http://www.boschautoparts.com/m/Pages/superplus.aspx

My Renix didn't like ngks..go figure.
Change every 15-20k. I generally change plug wires cap and rotor once a year regardless of miles.

 

[5-90]

For those of you who own a 1987-90 4.0L, what spark plug are you using? If I recall, the original specified by AMC (Chyrsler for you '88-90 folks) is a Champion RC9YC.

• If you're using something else, please explain why you chose it.
• Do you run a hotter or cooler plug?
• How many miles are you experiencing between inspecting/replacing the set?

AP3924. I quit using Champions years ago - when a set I had in my old Bug exploded on me on I-65 for no apparent reason. The Autolites have treated me well ever since (for anything exotic, I'll use Bosch. For small engines, I still use Champs - they're easier to find.)

I haven't really tracked the service life of the plugs; I just check 'em once a year, and have a set on the shelf if replacement is indicated. That was the pattern I'd used before, and the pattern I'll keep using - no reason to not change, that I can think of.

Cap & Rotor? BorgWarner w/brass terminals.

Wires? I get a roll of Accel 8mm resistance core, make new when the set fails resistance check.

 

[wilcharl]

I'm running Champ Truck plugs ... Gimmick (perhaps) but they were on clearance. Wires... Mopar Performance (blue) (again a clearance deal) and cap and rotor are from rock auto (again clearance but w/brass)

 

[sjx40250]

I run Splitfires. The only reason is that they were available in my tool box and were the only ones that I could get my rig to pass emissions in Oregon. The engine has a Borla exhaust system from head to tail and aftermarket injectors from 50Motorsports (sp?). At the time of testing they would give you results if you failed. I went through 3 times with different adjustments on my MAP and plotted the curves against voltage. There was no way I was going to get the cross over point between HC and CO2 to be below the acceptable limits for each. Put the splitfires in and passed.