I just swapped out my worn spark plugs (NGK BKR5ES) for a set of
(NGK BKR6ES). They have a higher heat range, are stated as being an option (along with BKR7ES) in the owner's manual, and are all the parts store had in stock.

The car seems to be sputtering a bit more at idle. Anyone else had this issue?

 

The 5 is a "hotter" version than 6 while the 7 is colder.

"sputtering at idle" ............... when the engine is cold too? ............. if so you simply have a crap set of plugs (perhaps only one of them). If it only happens when the engine is hot then you may also have a crap set of plugs (perhaps only one of them).

IMO changing one plug heat range up or down should not result in a noticeable change in idle performance if they are gapped properly (don't assume they come out the box with the exact same gap).

Did you perhaps damage a plug lead/connector or crack the porcelain on the plug while installing the new plugs?

Fit the old plugs and see if the idle sputter goes away then you know................

 

Good call, I assumed they had proper gap. I will pull them and double check.

 

I wonder if you're having injector issues. It's also not *just* at idle- it's got that weird feeling form 2-3000rpm as well. I'm guessing they're related.

Try a bottle of good injector cleaner- it certainly can't hurt.

Could also be your distributor going bad (they get play in the gear assy and causes the spark to be erratic)... but I'd put my bets on the more simple stuff like dirty injectors and whatnot.

 

Front bank has Bosch units (new) I installed last year. Rears are still original. I have heard that running injector cleaners wasn't a good idea in the past since our injectors are known to be suicidal. What it your suggestion on injector cleaner? Got a particular brand you like?

Also (unrelated), the motor sounds a little more raspy than I remember...More like a VE...It's running fine tho, plenty of power on the expressway. No oil leak either, yay!!!

 

Just changed the plugs for some new 5ES units and added a bottle of Seafoam to the gas tank. Seems better now.

BTW, the 6ES plugs were definitely out of the gap specifications...