1J Gurus - spark plug advice

[whatthe?]

Well, the 1J in the lexus has started idling a bit average (sounding like running on 5 cyls occasionally) So I pulled the plugs to have a look. The plugs don't look fouled, but considering the gap is suposed to be .8mm, a few of them were well over that. They were only double posted coppers (Champion RC8DMC) so it's probably as good a time as any for a change.

Since this engine runs a bit of boost on a regular basis, I figured I'd probably want a colder than average plug, probably a 7. Can anyone running ~20 PSI in their 1J recommend a good 7 heat range platinum plug to suit it?

Cheers

[Mathew]

I don't know enough about your particular request to offer advice, but I have had plenty of experience with spark plugs. One thing I can say is that you should forget using champion spark plugs of any type and take my advice and swap to bosch plugs. Honestly I have seen second hand bosch plugs out perform brand new champions on several occasions. Please give them a try, you won't be dissapointed!

Matt

[sbyder]

dont use platinum. Use a generic copper plug. BKR7E's are ideal.

[IN 05 NT]

NGK or BOSCH are the way to go, CHAMPION has lifted its game, but few years ago, you open a brand new box of champions and you were gauranteed that 1 in 10 was going to be faulty n cause a missfire.....shit plugs still tho.

[mrshin]

NGK copper = The Plug. Has even been known to partially cure cases of Australian Idle for short periods on locally produced vehicles.

[whatthe?]

Chucked in some BKR7E11 plugs and gapped them to .8mm. Problem solvered

Cheers all

[chris davey]

FYI people also use BCPR7e's gapped to .8mm. They are apparently a bit better thank bkr's. You may need .7mm for 20psi also.

[The Real Roadrunner]

the only difference between bkr and bcp is the height of the plug according to ngk distributors.
they are the same length seat to tip but the ceramic height is different ones 5mm longer.

[jampac]

The BCP plugs are built to prevent flash over from occurring. The BKR plugs are OEM fitment were as the BCP plugs are aftermarket NGK plugs.

[1JZ-Rolla]

What is flash over? I've never understood the difference between BKR & BCP with the projected insulator nose vs ISO projector nose and what it actually means.

[The Real Roadrunner]

bcp plugs are the replacment plug for rb engines and probably many others .
please explain flash over as ive never heard of it before and ive been involved in a couple of big cars.

[Mathew]

A quote from the bosch spark plugs site -
"Flashover- Occurs when the spark does not jump between the electrodes within the combustion chamber, but instead jumps between the metal shell and the terminal on top of the plug. This will always cause a misfire since the air/fuel mixture will not be ignited."
Hope this helps!

Matt

[1JZ-Rolla]

As i'm expecting to retune my 1J on 20psi soon, I switched from Denso PK20R8 platinums (equivalent to NKG heat range 6, gapped at 0.8mm) to NGK BCPR7ES gapped at 0.7mm.

I'm not sure whether its the smaller gap, or the colder heat range, but now the car feels sluggish compared to the old plugs, particularly lacking in the midrange where it used to come on really strong. It doesn't misfire under load or anything, just feels flat, like when you have ignition timing too retarded. Also, under very light load and at idle the engine misses every now and then, but I expected that from the smaller gaps.

Any body else had similar experience, or are you all running a bigger plug gap?

Cheers
Phil

[The Real Roadrunner]

open the gap back up, the bigger the spark the better the burn. you should only gap down if the car misses up top (but i would upgrade the ign setup instead).
cheers

[chris davey]

At present I have BKR7e's gapped to .7mm. I also have some BCPR7e's to put in which I was also going to gap to .7mm. As it is so long since I have run a 6 heat range plug I couldn't tell you what the difference was. I am going to put the BCPR's in prior to the dyno tomorrow so I will let you know how they go. I am also going to run about 20psi plus nitrous.

BTW if your coils are in good nic and you are using the x6 igniter I would think that is a pretty strong ignition system already. The next step is to upgrade to bosch coils and leads. I was only going to do that if it was really needed though. Shane picked up 40hp from this upgrade. He uses BCPR6's from memory though. (used)