1jz idling issue and running rich

[ma70suprawoner]

hey guys i just put new plugs in my 1jz the other day and now its running rich and and the idle is jumping up and down a by just a couple hundered rpms so it will go from 700rpm down to 500 rpm at idle. it has also died on my a couple times. i did not have this issue before when i had my set of iridium ngk's in my car yesterday i put in a set of ngk 3330's and now im having the idle and running rish issue i checked my isvc and its getting 12v also tps is brand new and so are the rest of the sensors on the engine could it be the gap of the plug ? any help is much appreciated would diffent plugs make it have idle issues when they were gaped at the same tollorence as the iridium plugs ? or do copper plugs have a different gap

 

[ma70suprawoner]

so i took the copper plugs out checked them they looked fine checked my coil packs no cracks checked the isvc its getting 12v to it checked my tps for carbon build up witch i had an issue with when i first installed the motor its clean and the sensor is brand new and its also getting 12v so i put back the iridium plugs back in and boom works perfect its not running rich anymore and idleing perfect HAHAHAHAHAHA WTF

 

[te72]

I've always run copper plugs in the Supras and just change them every year or so. They may not have the most stable idle, but they run good where it counts.

 

[f00g00]

What gap are you running on the coppers? According to NGK's website the NGK Iridiums as well as all the plugs for a 2JZGTE
(1JZGTE Swappable)are pre-gapped to .044. If you gapped the coppers to that then there is your problem, its way too much. Try a gap of .028 and see how it runs under boost, if it starts breaking up, lower by .002 to .026 etc. till it runs well under full boost. Higher boost you will need a closer gap for coppers.
If you re gap (not recommended) the iridiums be careful because the tips break off really easy.

 

[ma70suprawoner]

i have my iridium plugs gaped to .025 and it runs smooth as silk so i put the coppers in without gap and went for a drive and i got spark break up at full throttle/boost so i gapped them down to .025 and ran them no more spark break up on boost but idle was jumpy and ran to rich for stock 1jzgte so i put the iridium plugs back in and i have no issues so im just going to run iridium plugs from here on out

 

[te72]

Still having a hard time understanding how the plug choice will affect how much fuel the engine is fed considering the sensor that tells the injectors how much to spit in is before the plug...

Oh, and never trust a "pre-gapped" plug. I've seen them range by as much as 0.010" between the same brand of plug, same model.